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[ { "plaintext": "In communication, a code word is an element of a standardized code or protocol. Each code word is assembled in accordance with the specific rules of the code and assigned a unique meaning. Code words are typically used for reasons of reliability, clarity, brevity, or secrecy.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5177, 5225, 28030850 ], "anchor_spans": [ [ 3, 16 ], [ 62, 66 ], [ 70, 78 ] ] }, { "plaintext": " Code word (figure of speech)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1654771 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Coded set", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 40890 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Commercial code (communications)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 28739060 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Compartmentalization (information security)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 6235902 ], "anchor_spans": [ [ 1, 44 ] ] }, { "plaintext": " Duress code", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 10103412 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Error correction and detection", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 10375 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Marine VHF radio", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 508181 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Password", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 24304 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Safeword", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 70261 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Spelling alphabet", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 7098800 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": "UNHCR Procedure for Radio Communication", "section_idx": 2, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " UNHCR Procedure for Radio Communication", "section_idx": 3, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Data_transmission", "Cryptography" ]

[]

[ { "plaintext": "Coding may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Computer programming, the process of creating and maintaining the source code of computer programs", "section_idx": 1, "section_name": "Computer science", "target_page_ids": [ 5311 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Line coding, in data storage", "section_idx": 1, "section_name": "Computer science", "target_page_ids": [ 41317 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Source coding, compression used in data transmission", "section_idx": 1, "section_name": "Computer science", "target_page_ids": [ 8013 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Coding theory", "section_idx": 1, "section_name": "Computer science", "target_page_ids": [ 321869 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Channel coding, in coding theory", "section_idx": 1, "section_name": "Computer science", "target_page_ids": [ 4237207 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Coding (social sciences), an analytical process in which data are categorized for analysis", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 8989793 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Coding strand of DNA in molecular biology", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 509959 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Legal coding, the process of creating summary or keyword data from a document in the legal profession", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 9870300 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Medical coding, representation of medical diagnoses and procedures in standard code numbers", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 13522147 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Queer coding", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 62562485 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Code", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 5225 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": " Entropy encoding", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 46680 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Transform coding", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 50914 ], "anchor_spans": [ [ 1, 17 ] ] } ]

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[ { "plaintext": "In physics, coherence length is the propagation distance over which a coherent wave (e.g. an electromagnetic wave) maintains a specified degree of coherence. Wave interference is strong when the paths taken by all of the interfering waves differ by less than the coherence length. A wave with a longer coherence length is closer to a perfect sinusoidal wave. Coherence length is important in holography and telecommunications engineering.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22939, 5017866, 240011, 9426, 1802672, 15112, 66338, 8774050 ], "anchor_spans": [ [ 3, 10 ], [ 36, 47 ], [ 70, 78 ], [ 93, 113 ], [ 137, 156 ], [ 159, 176 ], [ 393, 403 ], [ 408, 438 ] ] }, { "plaintext": "This article focuses on the coherence of classical electromagnetic fields. In quantum mechanics, there is a mathematically analogous concept of the quantum coherence length of a wave function.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 151066, 25202, 240011, 145343 ], "anchor_spans": [ [ 41, 50 ], [ 79, 96 ], [ 149, 166 ], [ 179, 192 ] ] }, { "plaintext": "In radio-band systems, the coherence length is approximated by", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where is the speed of light in a vacuum, is the refractive index of the medium, and is the bandwidth of the source or is the signal wavelength and is the width of the range of wavelengths in the signal.", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [ 25880, 1553317, 3967 ], "anchor_spans": [ [ 50, 66 ], [ 74, 80 ], [ 94, 103 ] ] }, { "plaintext": "In optical communications, assuming that the source has a Gaussian emission spectrum, the coherence length is given by ", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [ 47867 ], "anchor_spans": [ [ 11, 25 ] ] }, { "plaintext": "where is the central wavelength of the source, is the refractive index of the medium, and is the (FWHM) spectral width of the source. If the source has a Gaussian spectrum with FWHM spectral width , then a path offset of will reduce the fringe visibility to 50%.", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [ 33125, 25880, 1553317, 41729, 41200, 1847015 ], "anchor_spans": [ [ 22, 32 ], [ 56, 72 ], [ 80, 86 ], [ 107, 121 ], [ 180, 184 ], [ 241, 258 ] ] }, { "plaintext": "The constant is roughly . Some authors give it as , while others give it as .", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Coherence length is usually applied to the optical regime.", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The expression above is a frequently used approximation. Due to ambiguities in the definition of spectral width of a source, however, the following definition of coherence length has been suggested:", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The coherence length can be measured using a Michelson interferometer and is the optical path length difference of a self-interfering laser beam which corresponds to fringe visibility, where the fringe visibility is defined as", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [ 582263, 41461, 17556 ], "anchor_spans": [ [ 45, 69 ], [ 81, 100 ], [ 134, 144 ] ] }, { "plaintext": "where is the fringe intensity.", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In long-distance transmission systems, the coherence length may be reduced by propagation factors such as dispersion, scattering, and diffraction.", "section_idx": 1, "section_name": "Formulas", "target_page_ids": [ 609152, 172333, 164483, 8603 ], "anchor_spans": [ [ 17, 29 ], [ 106, 116 ], [ 118, 128 ], [ 134, 145 ] ] }, { "plaintext": "Multimode helium–neon lasers have a typical coherence length of 20cm, while the coherence length of single-mode lasers can exceed 100m. Semiconductor lasers reach some 100m, but small, inexpensive semiconductor lasers have shorter lengths, with one source claiming 20cm. Singlemode fiber lasers with linewidths of a few kHz can have coherence lengths exceeding 100km. Similar coherence lengths can be reached with optical frequency combs due to the narrow linewidth of each tooth. Non-zero visibility is present only for short intervals of pulses repeated after cavity length distances up to this long coherence length.", "section_idx": 2, "section_name": "Lasers", "target_page_ids": [ 378269, 142258, 4555508, 30121934, 4555635 ], "anchor_spans": [ [ 10, 27 ], [ 136, 155 ], [ 282, 293 ], [ 300, 310 ], [ 422, 436 ] ] }, { "plaintext": "Tolansky's An introduction to Interferometry has a chapter on sources which quotes a line width of around 0.052 angstroms for each of the Sodium D lines in an uncooled low-pressure sodium lamp, corresponding to a coherence length of around 67mm for each line by itself. Cooling the low pressure sodium discharge to liquid nitrogen temperatures increases the individual D line coherence length by a factor of 6. A very narrow-band interference filter would be required to isolate an individual D line.", "section_idx": 3, "section_name": "Other light sources", "target_page_ids": [ 306364 ], "anchor_spans": [ [ 315, 330 ] ] }, { "plaintext": " Coherence time", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 40894 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Superconducting coherence length", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 4393828 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Spatial coherence", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 240011 ], "anchor_spans": [ [ 1, 18 ] ] } ]

[ "Electromagnetic_radiation", "Physical_optics", "Waves" ]

[]

[ { "plaintext": "For an electromagnetic wave, the coherence time is the time over which a propagating wave (especially a laser or maser beam) may be considered coherent, meaning that its phase is, on average, predictable.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9426, 30012, 17556, 19957, 240011, 24047 ], "anchor_spans": [ [ 7, 27 ], [ 55, 59 ], [ 104, 109 ], [ 113, 118 ], [ 143, 151 ], [ 170, 175 ] ] }, { "plaintext": "In long-distance transmission systems, the coherence time may be reduced by propagation factors such as dispersion, scattering, and diffraction.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 5017866, 172333, 164483, 8603 ], "anchor_spans": [ [ 17, 37 ], [ 76, 87 ], [ 104, 114 ], [ 116, 126 ], [ 132, 143 ] ] }, { "plaintext": "The coherence time, usually designated , is calculated by dividing the coherence length by the phase velocity of light in a medium; approximately given by", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40893, 25098, 17939 ], "anchor_spans": [ [ 71, 87 ], [ 95, 109 ], [ 113, 118 ] ] }, { "plaintext": "where is the central wavelength of the source, and is the spectral width of the source in units of frequency and wavelength respectively, and is the speed of light in vacuum.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33125, 41729, 28736 ], "anchor_spans": [ [ 22, 32 ], [ 61, 75 ], [ 153, 167 ] ] }, { "plaintext": "A single mode fiber laser has a linewidth of a few kHz, corresponding to a coherence time of a few hundred microseconds. Hydrogen masers have linewidth around 1Hz, corresponding to a coherence time of about one second. Their coherence length approximately corresponds to the distance from the Earth to the Moon.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 4555508 ], "anchor_spans": [ [ 14, 25 ] ] }, { "plaintext": "As of 2022, research groups worldwide have demonstrated superconducting qubits with coherence times up to several 100 µs.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26884, 25284, 36156 ], "anchor_spans": [ [ 56, 71 ], [ 72, 78 ], [ 118, 120 ] ] }, { "plaintext": " Atomic coherence", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1859847 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Temporal coherence", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 240011 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Degree of coherence", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1802672 ], "anchor_spans": [ [ 1, 20 ] ] } ]

[ "Electromagnetic_radiation", "Physical_optics", "Radio_frequency_propagation" ]

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[ { "plaintext": "Collective routing is routing in which a switching center automatically delivers messages to a specified list of destinations.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 25750, 26668156, 41367 ], "anchor_spans": [ [ 22, 29 ], [ 41, 57 ], [ 81, 88 ] ] }, { "plaintext": "Collective routing avoids the need to list each single address in the message heading.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8168925 ], "anchor_spans": [ [ 55, 62 ] ] }, { "plaintext": "Major relay stations usually transmit messages bearing collective-routing indicators to tributary, minor, and other major relay stations.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26590 ], "anchor_spans": [ [ 6, 11 ] ] } ]

[ "Routing" ]

[]

[ { "plaintext": "In telecommunications, a collinear antenna array (sometimes colinear antenna array) is an array of dipole or quarter-wave antennas mounted in such a manner that the corresponding elements of each antenna are parallel and collinear; that is, they are located along a common axis. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 31417095, 465156, 2874126, 187317, 3189581 ], "anchor_spans": [ [ 3, 20 ], [ 90, 95 ], [ 99, 105 ], [ 109, 130 ], [ 196, 203 ], [ 221, 230 ] ] }, { "plaintext": "Collinear arrays are high gain omnidirectional antennas. Both dipoles and quarter-wavelength monopoles have an omnidirectional radiation pattern in free space when oriented vertically; they radiate equal radio power in all azimuthal directions perpendicular to the antenna, with the signal strength dropping to zero on the antenna axis. The purpose of stacking multiple antennas in a vertical collinear array is to increase the power radiated in horizontal directions and reduce the power radiated into the sky or down toward the earth, where it is wasted. They radiate vertically polarized radio waves. Theoretically, when stacking idealized lossless antennas in such a fashion, doubling their number will produce double the gain, with an increase of 3.01 dB. In practice, the gain realized will be below this due to imperfect radiation spread and losses.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 342372, 342372, 41620, 47487, 41316, 8410 ], "anchor_spans": [ [ 31, 54 ], [ 112, 127 ], [ 128, 145 ], [ 224, 231 ], [ 572, 592 ], [ 760, 762 ] ] }, { "plaintext": "Collinear arrays are frequently constructed as a stack of dipoles, but can also be constructed as a stack of phased quarter-wave antennas. In this configuration, the individual radiators within the array are often constructed of coaxial feedlines with the center conductor of one element being connected electrically to the shield of the one above, and so on in alternating phase for as many elements are specified by gain or overall length requirements. The final or 'top' element in the stack is a quarter-wave radiator connected directly to the center conductor of the element below it. This style of collinear antenna is usually housed in a fiberglass radome, to provide both support and environmental protection to the relatively fragile coaxial elements.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 46380, 174431, 591552 ], "anchor_spans": [ [ 229, 246 ], [ 645, 655 ], [ 656, 662 ] ] }, { "plaintext": "A third type of collinear array, rarely seen outside of amateur radio VHF/UHF applications, uses half-wavelength monopole elements with phasing coils between each consecutive pair of elements to achieve the necessary phase shift. This style tends to be less efficient due to coil losses, but has the advantage that it can be constructed with the elements supporting themselves, doing away with the need for a protective radome.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Collinear arrays are often used as the antennas for base stations for land mobile radio systems that communicate with mobile two-way radios in vehicles, such as police, fire, ambulance, and taxi dispatchers. They are also sometimes used for broadcasting.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3080842, 804074, 173088 ], "anchor_spans": [ [ 70, 94 ], [ 125, 138 ], [ 241, 253 ] ] } ]

[ "Radio_frequency_antenna_types", "Antennas_(radio)" ]

[]

[ { "plaintext": "In physics, a collision is any event in which two or more bodies exert forces on each other in a relatively short time. Although the most common use of the word collision refers to incidents in which two or more objects collide with great force, the scientific use of the term implies nothing about the magnitude of the force.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22939, 10902 ], "anchor_spans": [ [ 3, 10 ], [ 71, 76 ] ] }, { "plaintext": "Some examples of physical interactions that scientists would consider collisions are the following:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " When an insect lands on a plant's leaf, its legs are said to collide with the leaf.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " When a cat strides across a lawn, each contact that its paws make with the ground is considered a collision, as well as each brush of its fur against a blade of grass.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " When a boxer throws a punch, their fist is said to collide with the opponents body.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " When an astronomical object merges with a black hole, they are considered to collide.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 206542, 4650 ], "anchor_spans": [ [ 9, 28 ], [ 43, 53 ] ] }, { "plaintext": "Some colloquial uses of the word collision are the following:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A traffic collision involves at least one automobile.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 19740545 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " A mid-air collision occurs between airplanes.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 7281229 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " A ship collision accurately involves at least two moving maritime vessels hitting each other; the related term, Allision, describes when a moving ship strikes a stationary object (often, but not always, another ship).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9097643 ], "anchor_spans": [ [ 3, 17 ] ] }, { "plaintext": "In physics, collisions can be classified by the change in the total kinetic energy of the system before and after the collision:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 17327 ], "anchor_spans": [ [ 68, 82 ] ] }, { "plaintext": " If most or all of the total kinetic energy is lost (dissipated as heat, sound, etc. or absorbed by the objects themselves), the collision is said to be inelastic; such collisions involve objects coming to a full stop. An example of such a collision is a car crash, as cars crumple inward when crashing, rather than bouncing off of each other. This is by design, for the safety of the occupants and bystanders should a crash occur - the frame of the car absorbs the energy of the crash instead. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 164572, 65908, 4135156, 330341 ], "anchor_spans": [ [ 53, 63 ], [ 153, 162 ], [ 349, 361 ], [ 371, 394 ] ] }, { "plaintext": " If most of the kinetic energy is conserved (i.e. the objects continue moving afterwards), the collision is said to be elastic. An example of this is a baseball bat hitting a baseball - the kinetic energy of the bat is transferred to the ball, greatly increasing the ball's velocity. The sound of the bat hitting the ball represents the loss of energy.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 65907 ], "anchor_spans": [ [ 119, 126 ] ] }, { "plaintext": " And if all of the total kinetic energy is conserved (i.e. no energy is released as sound, heat, etc.), the collision is said to be perfectly elastic. Such a system is an idealization and cannot occur in reality, due to the second law of thermodynamics.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2049301, 133017 ], "anchor_spans": [ [ 171, 183 ], [ 224, 252 ] ] }, { "plaintext": "Collision is short-duration interaction between two bodies or more than two bodies simultaneously causing change in motion of bodies involved due to internal forces acted between them during this. Collisions involve forces (there is a change in velocity). The magnitude of the velocity difference just before impact is called the closing speed. All collisions conserve momentum. What distinguishes different types of collisions is whether they also conserve kinetic energy. The line of impact is the line that is collinear to the common normal of the surfaces that are closest or in contact during impact. This is the line along which internal force of collision acts during impact, and Newton's coefficient of restitution is defined only along this line. Collisions are of three types:", "section_idx": 1, "section_name": "Physics", "target_page_ids": [ 20491903, 20431, 17327, 3659503 ], "anchor_spans": [ [ 245, 253 ], [ 369, 377 ], [ 459, 473 ], [ 698, 724 ] ] }, { "plaintext": "perfectly elastic collision", "section_idx": 1, "section_name": "Physics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "inelastic collision", "section_idx": 1, "section_name": "Physics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "perfectly inelastic collision.", "section_idx": 1, "section_name": "Physics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Specifically, collisions can either be elastic, meaning they conserve both momentum and kinetic energy, or inelastic, meaning they conserve momentum but not kinetic energy.", "section_idx": 1, "section_name": "Physics", "target_page_ids": [ 65907, 65908 ], "anchor_spans": [ [ 39, 46 ], [ 107, 116 ] ] }, { "plaintext": "An inelastic collision is sometimes also called a plastic collision. A \"perfectly inelastic\" collision (also called a \"perfectly plastic\" collision) is a limiting case of inelastic collision in which the two bodies coalesce after impact.", "section_idx": 1, "section_name": "Physics", "target_page_ids": [ 40400729, 3567939 ], "anchor_spans": [ [ 154, 167 ], [ 215, 223 ] ] }, { "plaintext": "The degree to which a collision is elastic or inelastic is quantified by the coefficient of restitution, a value that generally ranges between zero and one. A perfectly elastic collision has a coefficient of restitution of one; a perfectly inelastic collision has a coefficient of restitution of zero.", "section_idx": 1, "section_name": "Physics", "target_page_ids": [ 3659503 ], "anchor_spans": [ [ 77, 103 ] ] }, { "plaintext": "There are two types of collisions between two bodies - 1) Head-on collisions or one-dimensional collisions - where the velocity of each body just before impact is along the line of impact, and 2) Non-head-on collisions, oblique collisions or two-dimensional collisions - where the velocity of each body just before impact is not along the line of impact.", "section_idx": 2, "section_name": "Types of collisions", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "According to the coefficient of restitution, there are two special cases of any collision as written below:", "section_idx": 2, "section_name": "Types of collisions", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A perfectly elastic collision is defined as one in which there is no loss of kinetic energy in the collision. In reality, any macroscopic collision between objects will convert some kinetic energy to internal energy and other forms of energy, so no large-scale impacts are perfectly elastic. However, some problems are sufficiently close to perfectly elastic that they can be approximated as such. In this case, the coefficient of restitution equals one.", "section_idx": 2, "section_name": "Types of collisions", "target_page_ids": [ 65907, 17327, 340757 ], "anchor_spans": [ [ 13, 30 ], [ 78, 92 ], [ 201, 216 ] ] }, { "plaintext": " An inelastic collision is one in which part of the kinetic energy is changed to some other form of energy in the collision. Momentum is conserved in inelastic collisions (as it is for elastic collisions), but one cannot track the kinetic energy through the collision since some of it is converted to other forms of energy. In this case, coefficient of restitution is not equal to one.", "section_idx": 2, "section_name": "Types of collisions", "target_page_ids": [ 65908, 20431 ], "anchor_spans": [ [ 4, 23 ], [ 125, 133 ] ] }, { "plaintext": "In any type of collision there is a phase when for a moment colliding bodies have the same velocity along the line of impact.Then the kinetic energy of bodies reduces to its minimum during this phase and may be called a maximum deformation phase for which momentarily the coefficient of restitution becomes one.", "section_idx": 2, "section_name": "Types of collisions", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Collisions in ideal gases approach perfectly elastic collisions, as do scattering interactions of sub-atomic particles which are deflected by the electromagnetic force. Some large-scale interactions like the slingshot type gravitational interactions between satellites and planets are almost perfectly elastic.", "section_idx": 2, "section_name": "Types of collisions", "target_page_ids": [ 65905, 212490, 9532 ], "anchor_spans": [ [ 14, 25 ], [ 98, 118 ], [ 146, 167 ] ] }, { "plaintext": "Collisions between hard spheres may be nearly elastic, so it is useful to calculate the limiting case of an elastic collision. The assumption of conservation of momentum as well as the conservation of kinetic energy makes possible the calculation of the final velocities in two-body collisions.", "section_idx": 2, "section_name": "Types of collisions", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In maritime law, it is occasionally desirable to distinguish between the situation of a vessel striking a moving object, and that of it striking a stationary object. The word \"allision\" is then used to mean the striking of a stationary object, while \"collision\" is used to mean the striking of a moving object. Thus, when two vessels run against each other, courts typically use the term collision whereas when one vessel runs against another, they typically use the term allision. The fixed object could also be a bridge or dock. While there is no great difference between the two terms and often they are even used interchangeably, determining the difference helps clarify the circumstances of emergencies and adapt accordingly. In the case of Vane Line Bunkering, Inc. v. Natalie D M/V, it was established that there was the presumption that the moving vessel is at fault, stating that \"presumption derives from the common-sense observation that moving vessels do not usually collide with stationary objects unless the [moving] vessel is mishandled in some way\". This is also referred to as The Oregon Rule.", "section_idx": 3, "section_name": "Allision", "target_page_ids": [ 77396, 3397, 676393 ], "anchor_spans": [ [ 3, 15 ], [ 517, 523 ], [ 527, 531 ] ] }, { "plaintext": "Relatively few problems involving collisions can be solved analytically; the remainder require numerical methods. An important problem in simulating collisions is determining whether two objects have in fact collided. This problem is called collision detection.", "section_idx": 4, "section_name": "Analytical vs. numerical approaches towards resolving collisions", "target_page_ids": [ 21506, 171552 ], "anchor_spans": [ [ 95, 112 ], [ 241, 260 ] ] }, { "plaintext": "Collisions play an important role in cue sports. Because the collisions between billiard balls are nearly elastic, and the balls roll on a surface that produces low rolling friction, their behavior is often used to illustrate Newton's laws of motion. After a zero-friction collision of a moving ball with a stationary one of equal mass, the angle between the directions of the two balls is 90 degrees. This is an important fact that professional billiards players take into account, although it assumes the ball is moving without any impact of friction across the table rather than rolling with friction.", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [ 3447, 618981, 1503750, 55212 ], "anchor_spans": [ [ 37, 47 ], [ 80, 94 ], [ 165, 181 ], [ 226, 249 ] ] }, { "plaintext": "Consider an elastic collision in two dimensions of any two masses m1 and m2, with respective initial velocities u1 and u2 where u2 = 0, and final velocities V1 and V2.", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Conservation of momentum gives m1u1 = m1V1 + m2V2.", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Conservation of energy for an elastic collision gives (1/2)m1|u1|2 = (1/2)m1|V1|2 + (1/2)m2|V2|2.", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Now consider the case m1 = m2: we obtain u1 = V1 + V2 and |u1|2 = |V1|2 + |V2|2.", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Taking the dot product of each side of the former equation with itself, |u1|2 = u1•u1 = |V1|2 + |V2|2 + 2V1•V2. Comparing this with the latter equation gives V1•V2 = 0, so they are perpendicular unless V1 is the zero vector (which occurs if and only if the collision is head-on).", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [ 157093, 14922 ], "anchor_spans": [ [ 11, 22 ], [ 238, 252 ] ] }, { "plaintext": "In a perfect inelastic collision, i.e., a zero coefficient of restitution, the colliding particles coalesce. It is necessary to consider conservation of momentum:", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [ 3659503, 3567939 ], "anchor_spans": [ [ 47, 73 ], [ 99, 107 ] ] }, { "plaintext": "where v is the final velocity, which is hence given by", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The reduction of total kinetic energy is equal to the total kinetic energy before the collision in a center of momentum frame with respect to the system of two particles, because in such a frame the kinetic energy after the collision is zero. In this frame most of the kinetic energy before the collision is that of the particle with the smaller mass. In another frame, in addition to the reduction of kinetic energy there may be a transfer of kinetic energy from one particle to the other; the fact that this depends on the frame shows how relative this is.", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [ 7844595 ], "anchor_spans": [ [ 101, 125 ] ] }, { "plaintext": "With time reversed we have the situation of two objects pushed away from each other, e.g. shooting a projectile, or a rocket applying thrust (compare the derivation of the Tsiolkovsky rocket equation).", "section_idx": 5, "section_name": "Examples of collisions that can be solved analytically", "target_page_ids": [ 144553, 26301, 37892, 772517 ], "anchor_spans": [ [ 101, 111 ], [ 118, 124 ], [ 134, 140 ], [ 154, 199 ] ] }, { "plaintext": "Collisions of an animal's foot or paw with the underlying substrate are generally termed ground reaction forces. These collisions are inelastic, as kinetic energy is not conserved. An important research topic in prosthetics is quantifying the forces generated during the foot-ground collisions associated with both disabled and non-disabled gait. This quantification typically requires subjects to walk across a force platform (sometimes called a \"force plate\") as well as detailed kinematic and dynamic (sometimes termed kinetic) analysis.", "section_idx": 6, "section_name": "Examples of collisions analyzed numerically", "target_page_ids": [ 72750, 14664386, 65914, 226020 ], "anchor_spans": [ [ 212, 223 ], [ 412, 426 ], [ 482, 491 ], [ 496, 503 ] ] }, { "plaintext": "Collisions can be used as an experimental technique to study material properties of objects and other physical phenomena.", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An object may deliberately be made to crash-land on another celestial body, to do measurements and send them to Earth before being destroyed, or to allow instruments elsewhere to observe the effect. See e.g.:", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "During Apollo 13, Apollo 14, Apollo 15, Apollo 16 and Apollo 17, the S-IVB (the rocket's third stage) was crashed into the Moon in order to perform seismic measurement used for characterizing the lunar core.", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [ 1770, 1968, 1969, 1970, 1971, 272021, 19331 ], "anchor_spans": [ [ 7, 16 ], [ 18, 27 ], [ 29, 38 ], [ 40, 49 ], [ 54, 63 ], [ 69, 74 ], [ 123, 127 ] ] }, { "plaintext": " Deep Impact", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [ 583263 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " SMART-1 - European Space Agency satellite", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [ 206217, 10363 ], "anchor_spans": [ [ 1, 8 ], [ 11, 32 ] ] }, { "plaintext": " Moon impact probe - ISRO probe and LCROSS with its spent Centaur Upper Stage - NASA Probe", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [ 19914731, 1019722, 5028666, 79533 ], "anchor_spans": [ [ 1, 18 ], [ 21, 25 ], [ 36, 42 ], [ 58, 77 ] ] }, { "plaintext": " Double Asteroid Redirection Test for Planetary defence (planned)", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [ 54431373, 174069 ], "anchor_spans": [ [ 1, 33 ], [ 38, 55 ] ] }, { "plaintext": "Let the linear, angular and internal momenta of a molecule be given by the set of r variables { pi }. The state of a molecule may then be described by the range δwi = δp1δp2δp3 ... δpr. There are many such ranges corresponding to different states; a specific state may be denoted by the index i. Two molecules undergoing a collision can thus be denoted by (i, j) (Such an ordered pair is sometimes known as a constellation.)", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [ 19555 ], "anchor_spans": [ [ 50, 58 ] ] }, { "plaintext": "It is convenient to suppose that two molecules exert a negligible effect on each other unless their center of gravity approach within a critical distance b. A collision therefore begins when the respective centers of gravity arrive at this critical distance, and is completed when they again reach this critical distance on their way apart. Under this model, a collision is completely described by the matrix , which refers to the constellation (i, j) before the collision, and the (in general different) constellation (k, l) after the collision.", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This notation is convenient in proving Boltzmann's H-theorem of statistical mechanics.", "section_idx": 7, "section_name": "Collisions used as an experimental tool", "target_page_ids": [ 424440, 28481 ], "anchor_spans": [ [ 51, 60 ], [ 64, 85 ] ] }, { "plaintext": "Types of attack by means of a deliberate collision include:", "section_idx": 8, "section_name": "Attack by means of a deliberate collision", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " striking with the body: unarmed striking, punching, kicking", "section_idx": 8, "section_name": "Attack by means of a deliberate collision", "target_page_ids": [ 574095, 509403, 16831 ], "anchor_spans": [ [ 33, 41 ], [ 43, 51 ], [ 53, 57 ] ] }, { "plaintext": " striking with a weapon, such as a sword, club or axe", "section_idx": 8, "section_name": "Attack by means of a deliberate collision", "target_page_ids": [ 27863, 619798, 18962267 ], "anchor_spans": [ [ 35, 40 ], [ 42, 46 ], [ 50, 53 ] ] }, { "plaintext": " ramming with an object or vehicle, e.g.:", "section_idx": 8, "section_name": "Attack by means of a deliberate collision", "target_page_ids": [ 2297825 ], "anchor_spans": [ [ 1, 8 ] ] }, { "plaintext": "Ram-raiding, the practice of driving a car into a building in order to break in", "section_idx": 8, "section_name": "Attack by means of a deliberate collision", "target_page_ids": [ 523367 ], "anchor_spans": [ [ 0, 11 ] ] }, { "plaintext": " a battering ram, medieval weapon used for breaking down large doors, also a modern version is used by police forces during raids", "section_idx": 8, "section_name": "Attack by means of a deliberate collision", "target_page_ids": [ 39831 ], "anchor_spans": [ [ 3, 16 ] ] }, { "plaintext": "An attacking collision with a distant object can be achieved by throwing or launching a projectile.", "section_idx": 8, "section_name": "Attack by means of a deliberate collision", "target_page_ids": [ 144553 ], "anchor_spans": [ [ 88, 98 ] ] }, { "plaintext": "Ballistic pendulum", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 4762888 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "Car accident", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 19740545 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Coefficient of restitution", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 3659503 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "Collision (telecommunications)", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 7320527 ], "anchor_spans": [ [ 0, 30 ] ] }, { "plaintext": "Collision detection", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 171552 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Elastic collision", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 65907 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Friction", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 11062 ], "anchor_spans": [ [ 0, 8 ] ] }, { "plaintext": "Head-on collision", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 1803364 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Impact crater", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 6416 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Impact event", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 63794 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Inelastic collision", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 65908 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Kinetic theory of gases - collisions between molecules", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 64204, 19555 ], "anchor_spans": [ [ 0, 23 ], [ 45, 53 ] ] }, { "plaintext": "Mid-air collision", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 7281229 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Projectile", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 144553 ], "anchor_spans": [ [ 0, 10 ] ] }, { "plaintext": "Satellite collision", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 21512627 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Space debris", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 266344 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Train wreck", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 963688 ], "anchor_spans": [ [ 0, 11 ] ] }, { "plaintext": " Reissued (1979) New York: Dover .", "section_idx": 11, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Three Dimensional Collision - Oblique inelastic collision between two homogeneous spheres.", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "One Dimensional Collision - One Dimensional Collision Flash Applet.", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Two Dimensional Collision - Two Dimensional Collision Flash Applet.", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Ütközés", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Collision", "Mechanics" ]

[ "crash", "💥" ]

[ { "plaintext": "In telecommunication, a combat-net radio (CNR) is a radio operating in a network that (a) provides a half-duplex circuit and (b) uses either a single radio frequency or a discrete set of radio frequencies when in a frequency hopping mode.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 15368428, 46545, 2112491, 346001, 42852, 26691, 46890, 516150 ], "anchor_spans": [ [ 3, 20 ], [ 52, 57 ], [ 73, 80 ], [ 101, 112 ], [ 113, 120 ], [ 150, 165 ], [ 180, 183 ], [ 215, 232 ], [ 233, 237 ] ] }, { "plaintext": "CNRs are primarily used for push-to-talk-operated radio nets for command and control of combat, combat support, and combat service support operations among military ground, sea, and air forces.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 358882, 7092305, 23210314, 52080664, 92357 ], "anchor_spans": [ [ 28, 40 ], [ 65, 84 ], [ 88, 94 ], [ 116, 138 ], [ 156, 164 ] ] }, { "plaintext": "In the United States, two military standards govern the use of combat net radios and the host applications that communicate over the network: MIL-STD-188-220 and MIL-STD-2045-47001. In addition to IETF RFCs governing UDP, TCP, and IPv4/IPv6, all seven layers of the OSI communications architecture are addressed. MIL-STD-2045-47001 covers layer 7 (application), while MIL-STD-188-220 covers layers 1 through 3 (physical, data link, and network).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2336660, 22747, 172179, 78300, 152949, 85024 ], "anchor_spans": [ [ 142, 149 ], [ 266, 297 ], [ 348, 359 ], [ 411, 419 ], [ 421, 430 ], [ 436, 443 ] ] }, { "plaintext": "AN/PRC-152 by Harris Corporation", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 11044785, 1674637 ], "anchor_spans": [ [ 0, 10 ], [ 14, 32 ] ] }, { "plaintext": "AN/PRC-117", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 11350058 ], "anchor_spans": [ [ 0, 10 ] ] }, { "plaintext": "AN/PRC-77", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 160494 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "SINCGARS", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 160524 ], "anchor_spans": [ [ 0, 8 ] ] }, { "plaintext": "AN/PRC-148 MBITR", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 9652491 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "PR4G by Thales Communications", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 13462530 ], "anchor_spans": [ [ 8, 29 ] ] }, { "plaintext": "PRC-525 by EID", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 51308379 ], "anchor_spans": [ [ 11, 14 ] ] }, { "plaintext": "Clansman", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 5989427 ], "anchor_spans": [ [ 0, 8 ] ] }, { "plaintext": "Leopard1 by Sat-Com Pty Ltd", "section_idx": 1, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "JTRS", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 1102237 ], "anchor_spans": [ [ 0, 4 ] ] }, { "plaintext": "Joint Electronics Type Designation System", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 1322528 ], "anchor_spans": [ [ 0, 41 ] ] }, { "plaintext": "Software-defined radio", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 83137 ], "anchor_spans": [ [ 0, 22 ] ] } ]

[ "Military_radio_systems" ]

[ "CNR", "UHF" ]

[ { "plaintext": "In telecommunication, a combined distribution frame (CDF) is a distribution frame that combines the functions of main and intermediate distribution frames and contains both vertical and horizontal terminating blocks. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 411837, 41344, 41280 ], "anchor_spans": [ [ 3, 20 ], [ 63, 81 ], [ 113, 117 ], [ 122, 153 ] ] }, { "plaintext": "The vertical blocks are used to terminate the permanent outside lines entering the station. Horizontal blocks are used to terminate inside plant equipment. This arrangement permits the association of any outside line with any desired terminal equipment. These connections are made either with twisted pair wire, normally referred to as jumper wire, or with optical fiber cables, normally referred to as jumper cables. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41267, 946963, 41786, 3372377 ], "anchor_spans": [ [ 132, 144 ], [ 212, 216 ], [ 234, 252 ], [ 357, 370 ] ] }, { "plaintext": "In technical control facilities, the vertical side may be used to terminate equipment as well as outside lines. The horizontal side is then used for jackfields and battery terminations.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3072613 ], "anchor_spans": [ [ 149, 159 ] ] } ]

[ "Broadcast_engineering", "Telephony_equipment" ]

[]

[ { "plaintext": "A comma-free code is block code in which no concatenation of two code words contains a valid code word that overlaps both.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1134659, 64474, 40891 ], "anchor_spans": [ [ 21, 31 ], [ 44, 57 ], [ 65, 74 ] ] }, { "plaintext": "Comma-free codes are also known as self-synchronizing block codes because no synchronization is required to find the beginning of a code word.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 28738 ], "anchor_spans": [ [ 77, 92 ] ] } ]

[ "Coding_theory" ]

[]

[ { "plaintext": "In telecommunication, a common battery is a single electrical power source used to energize more than one circuit, electronic component, equipment, or system. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 3270043, 346001, 1886820, 8286675 ], "anchor_spans": [ [ 3, 20 ], [ 62, 67 ], [ 106, 113 ], [ 115, 135 ], [ 151, 157 ] ] }, { "plaintext": "A common battery is usually a string of electrolytic cells and is usually centrally located to the equipment that it serves. In many telecommunications applications, the common battery is at a nominal −48 VDC. A central office common battery in the battery room supplies power to operate all directly connected instruments. Common battery may include one or more power conversion devices to transform commercial power to direct current, with a rechargeable battery floating across the output. Common battery operation largely replaced local batteries in each telephone in the early 20th century. It consists of two ends that emit opposing positive and negative charges", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 361021, 26668156, 1706048, 201487 ], "anchor_spans": [ [ 40, 57 ], [ 212, 226 ], [ 249, 261 ], [ 445, 465 ] ] }, { "plaintext": " List of battery types", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 6697721 ], "anchor_spans": [ [ 1, 22 ] ] } ]

[ "Telephony" ]

[]

[ { "plaintext": "In computing, booting is the process of starting a computer as initiated via hardware such as a button or by a software command. After it is switched on, a computer's central processing unit (CPU) has no software in its main memory, so some process must load software into memory before it can be executed. This may be done by hardware or firmware in the CPU, or by a separate processor in the computer system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5213, 7878457, 21808348, 5309, 5218, 5300, 41155 ], "anchor_spans": [ [ 3, 12 ], [ 51, 59 ], [ 77, 85 ], [ 111, 119 ], [ 167, 190 ], [ 220, 231 ], [ 339, 347 ] ] }, { "plaintext": "Restarting a computer also is called rebooting, which can be \"hard\", e.g. after electrical power to the CPU is switched from off to on, or \"soft\", where the power is not cut. On some systems, a soft boot may optionally clear RAM to zero. Both hard and soft booting can be initiated by hardware such as a button press or by a software command. Booting is complete when the operative runtime system, typically the operating system and some applications, is attained.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 32159470, 21306150, 2106840, 22194 ], "anchor_spans": [ [ 37, 46 ], [ 225, 228 ], [ 382, 396 ], [ 412, 428 ] ] }, { "plaintext": "The process of returning a computer from a state of sleep (suspension) does not involve booting; however, restoring it from a state of hibernation does. Minimally, some embedded systems do not require a noticeable boot sequence to begin functioning and when turned on may simply run operational programs that are stored in ROM. All computing systems are state machines, and a reboot may be the only method to return to a designated zero-state from an unintended, locked state.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2183606, 3220132, 46630, 10931 ], "anchor_spans": [ [ 52, 57 ], [ 135, 146 ], [ 169, 185 ], [ 354, 367 ] ] }, { "plaintext": "In addition to loading an operating system or stand-alone utility, the boot process can also load a storage dump program for diagnosing problems in an operating system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Boot is short for bootstrap or bootstrap load and derives from the phrase to pull oneself up by one's bootstraps. The usage calls attention to the requirement that, if most software is loaded onto a computer by other software already running on the computer, some mechanism must exist to load the initial software onto the computer. Early computers used a variety of ad-hoc methods to get a small program into memory to solve this problem. The invention of read-only memory (ROM) of various types solved this paradox by allowing computers to be shipped with a start up program that could not be erased. Growth in the capacity of ROM has allowed ever more elaborate start up procedures to be implemented.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 4211, 4211, 18934934 ], "anchor_spans": [ [ 18, 27 ], [ 74, 112 ], [ 457, 473 ] ] }, { "plaintext": "There are many different methods available to load a short initial program into a computer. These methods reach from simple, physical input to removable media that can hold more complex programs.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Early computers in the 1940s and 1950s were one-of-a-kind engineering efforts that could take weeks to program and program loading was one of many problems that had to be solved. An early computer, ENIAC, had no program stored in memory, but was set up for each problem by a configuration of interconnecting cables. Bootstrapping did not apply to ENIAC, whose hardware configuration was ready for solving problems as soon as power was applied.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 66572 ], "anchor_spans": [ [ 198, 203 ] ] }, { "plaintext": "The EDSAC system, the second stored-program computer to be built, used stepping switches to transfer a fixed program into memory when its start button was pressed. The program stored on this device, which David Wheeler completed in late 1948, loaded further instructions from punched tape and then executed them.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 10251, 831609, 532495, 49761 ], "anchor_spans": [ [ 4, 9 ], [ 71, 86 ], [ 205, 218 ], [ 276, 288 ] ] }, { "plaintext": "The first programmable computers for commercial sale, such as the UNIVAC I and the IBM 701 included features to make their operation simpler. They typically included instructions that performed a complete input or output operation. The same hardware logic could be used to load the contents of a punch card (the most typical ones) or other input media, such as a magnetic drum or magnetic tape, that contained a bootstrap program by pressing a single button. This booting concept was called a variety of names for IBM computers of the 1950s and early 1960s, but IBM used the term \"Initial Program Load\" with the IBM 7030 Stretch and later used it for their mainframe lines, starting with the System/360 in 1964.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 142981, 192701, 24420, 146961, 20505, 40379651, 149708, 29294 ], "anchor_spans": [ [ 66, 74 ], [ 83, 90 ], [ 296, 306 ], [ 363, 376 ], [ 380, 393 ], [ 514, 517 ], [ 612, 628 ], [ 692, 702 ] ] }, { "plaintext": "The IBM 701 computer (1952–1956) had a \"Load\" button that initiated reading of the first 36-bit word into main memory from a punched card in a card reader, a magnetic tape in a tape drive, or a magnetic drum unit, depending on the position of the Load Selector switch. The left 18-bit half-word was then executed as an instruction, which usually read additional words into memory. The loaded boot program was then executed, which, in turn, loaded a larger program from that medium into memory without further help from the human operator. The IBM 704, IBM 7090, and IBM 7094 had similar mechanisms, but with different load buttons for different devices. The term \"boot\" has been used in this sense since at least 1958.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 192701, 920064, 1613344, 6806, 24178036, 31109, 76492, 147332, 147332 ], "anchor_spans": [ [ 4, 11 ], [ 89, 95 ], [ 96, 100 ], [ 106, 117 ], [ 143, 154 ], [ 177, 187 ], [ 543, 550 ], [ 552, 560 ], [ 566, 574 ] ] }, { "plaintext": "Other IBM computers of that era had similar features. For example, the IBM 1401 system (c. 1958) used a card reader to load a program from a punched card. The 80 characters stored in the punched card were read into memory locations 001 to 080, then the computer would branch to memory location 001 to read its first stored instruction. This instruction was always the same: move the information in these first 80 memory locations to an assembly area where the information in punched cards 2, 3, 4, and so on, could be combined to form the stored program. Once this information was moved to the assembly area, the machine would branch to an instruction in location 080 (read a card) and the next card would be read and its information processed.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 92579 ], "anchor_spans": [ [ 71, 79 ] ] }, { "plaintext": "Another example was the IBM 650 (1953), a decimal machine, which had a group of ten 10-position switches on its operator panel which were addressable as a memory word (address 8000) and could be executed as an instruction. Thus setting the switches to 7004000400 and pressing the appropriate button would read the first card in the card reader into memory (op code 70), starting at address 400 and then jump to 400 to begin executing the program on that card. The IBM 7040 and 7044 have a similar mechanism, in which the Load button causes the instruction set up in the entry keys on the front panel is executed, and the channel that instruction sets up is given a command to transfer data to memory starting at address 00100; when that transfer finishes, the CPU jumps to address 00101.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 143676, 208006 ], "anchor_spans": [ [ 24, 31 ], [ 465, 482 ] ] }, { "plaintext": "IBM's competitors also offered single button program load.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The CDC 6600 (c. 1964) had a dead start panel with 144 toggle switches; the dead start switch entered 12 12-bit words from the toggle switches to the memory of peripheral processor (PP) 0 and initiated the load sequence by causing PP 0 to execute the code loaded into memory. PP 0 loaded the necessary code into its own memory and then initialized the other PPs.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 58661, 4120803 ], "anchor_spans": [ [ 5, 13 ], [ 161, 181 ] ] }, { "plaintext": " The GE 645 (c. 1965) had a \"SYSTEM BOOTLOAD\" button that, when pressed, caused one of the I/O controllers to load a 64-word program into memory from a diode read-only memory and deliver an interrupt to cause that program to start running.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 58659, 18934934 ], "anchor_spans": [ [ 5, 11 ], [ 158, 174 ] ] }, { "plaintext": " The first model of the PDP-10 had a \"READ IN\" button that, when pressed, reset the processor and started an I/O operation on a device specified by switches on the control panel, reading in a 36-bit word giving a target address and count for subsequent word reads; when the read completed, the processor started executing the code read in by jumping to the last word read in.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 23628 ], "anchor_spans": [ [ 24, 30 ] ] }, { "plaintext": "A noteworthy variation of this is found on the Burroughs B1700 where there is neither a bootstrap ROM nor a hardwired IPL operation. Instead, after the system is reset it reads and executes microinstructions sequentially from a cassette tape drive mounted on the front panel; this sets up a boot loader in RAM which is then executed. However, since this makes few assumptions about the system it can equally well be used to load diagnostic (Maintenance Test Routine) tapes which display an intelligible code on the front panel even in cases of gross CPU failure.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 4524, 1416356, 4793390 ], "anchor_spans": [ [ 47, 56 ], [ 57, 62 ], [ 515, 526 ] ] }, { "plaintext": "In the IBM System/360 and its successors, including the current z/Architecture machines, the boot process is known as Initial Program Load (IPL).", "section_idx": 1, "section_name": "History", "target_page_ids": [ 29294, 1856144, 28739443 ], "anchor_spans": [ [ 7, 21 ], [ 64, 78 ], [ 118, 138 ] ] }, { "plaintext": "IBM coined this term for the 7030 (Stretch), revived it for the design of the System/360, and continues to use it in those environments today. In the System/360 processors, an IPL is initiated by the computer operator by selecting the three hexadecimal digit device address (CUU; C=I/O Channel address, UU=Control unit and Device address) followed by pressing the LOAD button. On the high end System/360 models, most System/370 and some later systems, the functions of the switches and the LOAD button are simulated using selectable areas on the screen of a graphics console, often an IBM 2250-like device or an IBM 3270-like device. For example, on the System/370 Model 158, the keyboard sequence 0-7-X (zero, seven and X, in that order) results in an IPL from the device address which was keyed into the input area. The Amdahl 470V/6 and related CPUs supported four hexadecimal digits on those CPUs which had the optional second channel unit installed, for a total of 32 channels. Later, IBM would also support more than 16 channels.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 149708, 29294, 59785, 904051, 15154, 483650 ], "anchor_spans": [ [ 29, 43 ], [ 393, 403 ], [ 417, 427 ], [ 585, 593 ], [ 612, 620 ], [ 822, 828 ] ] }, { "plaintext": "The IPL function in the System/360 and its successors prior to IBM Z, and its compatibles such as Amdahl's, reads 24 bytes from an operator-specified device into main storage starting at real address zero. The second and third groups of eight bytes are treated as Channel Command Words (CCWs) to continue loading the startup program (the first CCW is always simulated by the CPU and consists of a Read IPL command, , with command chaining and suppress incorrect length indication being enforced). When the I/O channel commands are complete, the first group of eight bytes is then loaded into the processor's Program Status Word (PSW) and the startup program begins execution at the location designated by that PSW. The IPL device is usually a disk drive, hence the special significance of the read-type command, but exactly the same procedure is also used to IPL from other input-type devices, such as tape drives, or even card readers, in a device-independent manner, allowing, for example, the installation of an operating system on a brand-new computer from an OS initial distribution magnetic tape. For disk controllers, the command also causes the selected device to seek to cylinder , head , simulating a Seek cylinder and head command, , and to search for record , simulating a Search ID Equal command, ; seeks and searches are not simulated by tape and card controllers, as for these device classes a Read IPL command is simply a sequential read command.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 3968088, 2470370, 3299290 ], "anchor_spans": [ [ 63, 68 ], [ 264, 284 ], [ 608, 627 ] ] }, { "plaintext": "The disk, tape or card deck must contain a special program to load the actual operating system or standalone utility into main storage, and for this specific purpose \"IPL Text\" is placed on the disk by the stand-alone DASDI (Direct Access Storage Device Initialization) program or an equivalent program running under an operating system, e.g., ICKDSF, but IPL-able tapes and card decks are usually distributed with this \"IPL Text\" already present.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "IBM introduced some evolutionary changes in the IPL process, changing some details for System/370 Extended Architecture (S/370-XA) and later, and adding a new type of IPL for z/Architecture.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Minicomputers, starting with the Digital Equipment Corporation (DEC) PDP-5 and PDP-8 (1965) simplified design by using the CPU to assist input and output operations. This saved cost but made booting more complicated than pressing a single button. Minicomputers typically had some way to toggle in short programs by manipulating an array of switches on the front panel. Since the early minicomputers used magnetic-core memory, which did not lose its information when power was off, these bootstrap loaders would remain in place unless they were erased. Erasure sometimes happened accidentally when a program bug caused a loop that overwrote all of memory.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 20272, 7952, 1749594, 24364, 4793390, 78029 ], "anchor_spans": [ [ 0, 12 ], [ 33, 62 ], [ 69, 74 ], [ 79, 84 ], [ 356, 367 ], [ 404, 424 ] ] }, { "plaintext": "Other minicomputers with such simple form of booting include Hewlett-Packard's HP 2100 series (mid-1960s), the original Data General Nova (1969), and DEC's PDP-4 (1962) and PDP-11 (1970).", "section_idx": 1, "section_name": "History", "target_page_ids": [ 583880, 8654, 1749584, 24399 ], "anchor_spans": [ [ 79, 86 ], [ 120, 137 ], [ 156, 161 ], [ 173, 179 ] ] }, { "plaintext": "As the I/O operations needed to cause a read operation on a minicomputer I/O device were typically different for different device controllers, different bootstrap programs were needed for different devices.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "DEC later added, in 1971, an optional diode matrix read-only memory for the PDP-11 that stored a bootstrap program of up to 32 words (64 bytes). It consisted of a printed circuit card, the M792, that plugged into the Unibus and held a 32 by 16 array of semiconductor diodes. With all 512 diodes in place, the memory contained all \"one\" bits; the card was programmed by cutting off each diode whose bit was to be \"zero\". DEC also sold versions of the card, the BM792-Yx series, pre-programmed for many standard input devices by simply omitting the unneeded diodes. ", "section_idx": 1, "section_name": "History", "target_page_ids": [ 31506957, 18934934, 1300317 ], "anchor_spans": [ [ 38, 50 ], [ 51, 67 ], [ 217, 223 ] ] }, { "plaintext": "Following the older approach, the earlier PDP-1 has a hardware loader, such that an operator need only push the \"load\" switch to instruct the paper tape reader to load a program directly into core memory. The PDP-7, PDP-9, and PDP-15 successors to the PDP-4 have an added Read-In button to read a program in from paper tape and jump to it. The Data General Supernova used front panel switches to cause the computer to automatically load instructions into memory from a device specified by the front panel's data switches, and then jump to loaded code.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 23965, 49761, 38278, 1749586, 1749605, 8654 ], "anchor_spans": [ [ 42, 47 ], [ 142, 152 ], [ 209, 214 ], [ 216, 221 ], [ 227, 233 ], [ 357, 366 ] ] }, { "plaintext": "In a minicomputer with a paper tape reader, the first program to run in the boot process, the boot loader, would read into core memory either the second-stage boot loader (often called a Binary Loader) that could read paper tape with checksum or the operating system from an outside storage medium. Pseudocode for the boot loader might be as simple as the following eight instructions:", "section_idx": 1, "section_name": "History", "target_page_ids": [ 7538, 24185 ], "anchor_spans": [ [ 234, 242 ], [ 299, 309 ] ] }, { "plaintext": " Set the P register to 9", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Check paper tape reader ready", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " If not ready, jump to 2", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Read a byte from paper tape reader to accumulator", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Store accumulator to address in P register", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " If end of tape, jump to 9", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Increment the P register", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Jump to 2", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A related example is based on a loader for a Nicolet Instrument Corporation minicomputer of the 1970s, using the paper tape reader-punch unit on a Teletype Model 33 ASR teleprinter. The bytes of its second-stage loader are read from paper tape in reverse order.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 1507684, 31247 ], "anchor_spans": [ [ 147, 164 ], [ 169, 180 ] ] }, { "plaintext": " Set the P register to 106", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Check paper tape reader ready", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " If not ready, jump to 2", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Read a byte from paper tape reader to accumulator", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Store accumulator to address in P register", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Decrement the P register", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Jump to 2", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The length of the second stage loader is such that the final byte overwrites location 7. After the instruction in location 6 executes, location 7 starts the second stage loader executing. The second stage loader then waits for the much longer tape containing the operating system to be placed in the tape reader. The difference between the boot loader and second stage loader is the addition of checking code to trap paper tape read errors, a frequent occurrence with relatively low-cost, \"part-time-duty\" hardware, such as the Teletype Model 33 ASR. (Friden Flexowriters were far more reliable, but also comparatively costly.)", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The earliest microcomputers, such as the Altair 8800 (released first in 1975) and an even earlier, similar machine (based on the Intel 8008 CPU) had no bootstrapping hardware as such. When started, the CPU would see memory that would contain executable code containing only binary zeros—memory was cleared by resetting when powering up. The front panels of these machines carried toggle switches for entering addresses and data, one switch per bit of the computer memory word and address bus. Simple additions to the hardware permitted one memory location at a time to be loaded from those switches to store bootstrap code. Meanwhile, the CPU was kept from attempting to execute memory content. Once correctly loaded, the CPU was enabled to execute the bootstrapping code. This process, similar to that used for several earlier minicomputers, was tedious and had to be error-free.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 144949 ], "anchor_spans": [ [ 41, 52 ] ] }, { "plaintext": "The introduction of integrated circuit read-only memory (ROM), with its many variants, including mask-programmed ROMs, programmable ROMs (PROM), erasable programmable ROMs (EPROM), and flash memory, reduced the physical size and cost of ROM. This allowed firmware boot programs to be included as part of the computer. ", "section_idx": 1, "section_name": "History", "target_page_ids": [ 18934934, 18934934, 49716, 73333, 50595, 41155 ], "anchor_spans": [ [ 39, 55 ], [ 97, 116 ], [ 119, 135 ], [ 145, 170 ], [ 185, 197 ], [ 255, 263 ] ] }, { "plaintext": "The Data General Nova 1200 (1970) and Nova 800 (1971) had a program load switch that, in combination with options that provided two ROM chips, loaded a program into main memory from those ROM chips and jumped to it. Digital Equipment Corporation introduced the integrated-circuit-ROM-based BM873 (1974), M9301 (1977), M9312 (1978), REV11-A and REV11-C, MRV11-C, and MRV11-D ROM memories, all usable as bootstrap ROMs. The PDP-11/34 (1976), PDP-11/60 (1977), PDP-11/24 (1979), and most later models include boot ROM modules.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 8654, 8654 ], "anchor_spans": [ [ 17, 26 ], [ 38, 46 ] ] }, { "plaintext": "An Italian telephone switching computer, called \"Gruppi Speciali\", patented in 1975 by Alberto Ciaramella, a researcher at CSELT, included an (external) ROM. Gruppi Speciali was, starting from 1975, a fully single-button machine booting into the operating system from a ROM memory composed from semiconductors, not from ferrite cores. Although the ROM device was not natively embedded in the computer of Gruppi Speciali, due to the design of the machine, it also allowed the single-button ROM booting in machines not designed for that (therefore, this \"bootstrap device\" was architecture-independent), e.g. the PDP-11. Storing the state of the machine after the switch-off was also in place, which was another critical feature in the telephone switching contest.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 52343130, 44654065 ], "anchor_spans": [ [ 87, 105 ], [ 123, 128 ] ] }, { "plaintext": "Some minicomputers and superminicomputers include a separate console processor that bootstraps the main processor. The PDP-11/44 had an Intel 8085 as a console processor; the VAX-11/780, the first member of Digital's VAX line of 32-bit superminicomputers, had an LSI-11-based console processor, and the VAX-11/730 had an 8085-based console processor. These console processors could boot the main processor from various storage devices.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 194808, 97302, 3974104, 32517, 24399 ], "anchor_spans": [ [ 23, 40 ], [ 137, 147 ], [ 176, 186 ], [ 218, 221 ], [ 264, 270 ] ] }, { "plaintext": "Some other superminicomputers, such as the VAX-11/750, implement console functions, including the first stage of booting, in CPU microcode.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Typically, a microprocessor will, after a reset or power-on condition, perform a start-up process that usually takes the form of \"begin execution of the code that is found starting at a specific address\" or \"look for a multibyte code at a specific address and jump to the indicated location to begin execution\". A system built using that microprocessor will have the permanent ROM occupying these special locations so that the system always begins operating without operator assistance. For example, Intel x86 processors always start by running the instructions beginning at F000:FFF0, while for the MOS 6502 processor, initialization begins by reading a two-byte vector address at $FFFD (MS byte) and $FFFC (LS byte) and jumping to that location to run the bootstrap code.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 34198, 20297 ], "anchor_spans": [ [ 500, 509 ], [ 600, 608 ] ] }, { "plaintext": "Apple Inc.'s first computer, the Apple 1 introduced in 1976, featured PROM chips that eliminated the need for a front panel for the boot process (as was the case with the Altair 8800) in a commercial computer. According to Apple's ad announcing it \"No More Switches, No More Lights ... the firmware in PROMS enables you to enter, display and debug programs (all in hex) from the keyboard.\"", "section_idx": 1, "section_name": "History", "target_page_ids": [ 856, 1344 ], "anchor_spans": [ [ 0, 10 ], [ 33, 40 ] ] }, { "plaintext": "Due to the expense of read-only memory at the time, the Apple II series booted its disk operating systems using a series of very small incremental steps, each passing control onward to the next phase of the gradually more complex boot process. (See Boot loader). Because so little of the disk operating system relied on ROM, the hardware was also extremely flexible and supported a wide range of customized disk copy protection mechanisms. (See History.)", "section_idx": 1, "section_name": "History", "target_page_ids": [ 2116, 253848, 219210, 29213 ], "anchor_spans": [ [ 56, 71 ], [ 249, 261 ], [ 413, 428 ], [ 446, 454 ] ] }, { "plaintext": "Some operating systems, most notably pre-1995 Macintosh systems from Apple, are so closely interwoven with their hardware that it is impossible to natively boot an operating system other than the standard one. This is the opposite extreme of the scenario using switches mentioned above; it is highly inflexible but relatively error-proof and foolproof as long as all hardware is working normally. A common solution in such situations is to design a boot loader that works as a program belonging to the standard OS that hijacks the system and loads the alternative OS. This technique was used by Apple for its A/UX Unix implementation and copied by various freeware operating systems and BeOS Personal Edition 5.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 19006979, 856, 238604, 4801 ], "anchor_spans": [ [ 46, 55 ], [ 69, 74 ], [ 609, 613 ], [ 687, 710 ] ] }, { "plaintext": "Some machines, like the Atari ST microcomputer, were \"instant-on\", with the operating system executing from a ROM. Retrieval of the OS from secondary or tertiary store was thus eliminated as one of the characteristic operations for bootstrapping. To allow system customizations, accessories, and other support software to be loaded automatically, the Atari's floppy drive was read for additional components during the boot process. There was a timeout delay that provided time to manually insert a floppy as the system searched for the extra components. This could be avoided by inserting a blank disk. The Atari ST hardware was also designed so the cartridge slot could provide native program execution for gaming purposes as a holdover from Atari's legacy making electronic games; by inserting the Spectre GCR cartridge with the Macintosh system ROM in the game slot and turning the Atari on, it could \"natively boot\" the Macintosh operating system rather than Atari's own TOS.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 2141, 48144, 18934934, 3629889, 12098077 ], "anchor_spans": [ [ 24, 32 ], [ 33, 46 ], [ 110, 113 ], [ 800, 811 ], [ 975, 978 ] ] }, { "plaintext": "The IBM Personal Computer included ROM-based firmware called the BIOS; one of the functions of that firmware was to perform a power-on self test when the machine was powered up, and then to read software from a boot device and execute it. Firmware compatible with the BIOS on the IBM Personal Computer is used in IBM PC compatible computers. The UEFI was developed by Intel, originally for Itanium-based machines, and later also used as an alternative to the BIOS in x86-based machines, including Apple Macs using Intel processors.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 15032, 4473, 1699425, 49803, 866065, 15454, 34198, 3698317 ], "anchor_spans": [ [ 4, 25 ], [ 65, 69 ], [ 126, 144 ], [ 313, 330 ], [ 346, 350 ], [ 390, 397 ], [ 467, 470 ], [ 497, 530 ] ] }, { "plaintext": "Unix workstations originally had vendor-specific ROM-based firmware. Sun Microsystems later developed OpenBoot, later known as Open Firmware, which incorporated a Forth interpreter, with much of the firmware being written in Forth. It was standardized by the IEEE as IEEE standard ; firmware that implements that standard was used in PowerPC-based Macs and some other PowerPC-based machines, as well as Sun's own SPARC-based computers. The Advanced RISC Computing specification defined another firmware standard, which was implemented on some MIPS-based and Alpha-based machines and the SGI Visual Workstation x86-based workstations.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 68181, 26980, 209452, 11012, 56938, 24281, 19006979, 36954, 1362808, 20170, 8971, 1363848 ], "anchor_spans": [ [ 0, 16 ], [ 69, 85 ], [ 102, 110 ], [ 163, 168 ], [ 259, 263 ], [ 334, 341 ], [ 348, 352 ], [ 413, 418 ], [ 440, 463 ], [ 543, 547 ], [ 558, 563 ], [ 587, 609 ] ] }, { "plaintext": "When a computer is turned off, its softwareincluding operating systems, application code, and dataremains stored on non-volatile memory. When the computer is powered on, it typically does not have an operating system or its loader in random-access memory (RAM). The computer first executes a relatively small program stored in read-only memory (ROM, and later EEPROM, NOR flash) along with some needed data, to initialize CPU and motherboard, to initialize RAM (especially on x86 systems), to access the nonvolatile device (usually block device, e.g. NAND flash) or devices from which the operating system programs and data can be loaded into RAM.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 780629, 21306150, 18934934, 50597, 50595, 21306150, 18016986 ], "anchor_spans": [ [ 116, 135 ], [ 234, 254 ], [ 327, 343 ], [ 360, 366 ], [ 368, 377 ], [ 457, 460 ], [ 532, 544 ] ] }, { "plaintext": "The small program that starts this sequence is known as a bootstrap loader, bootstrap or boot loader. Often, multiple-stage boot loaders are used, during which several programs of increasing complexity load one after the other in a process of chain loading.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 5481027 ], "anchor_spans": [ [ 243, 256 ] ] }, { "plaintext": "Some earlier computer systems, upon receiving a boot signal from a human operator or a peripheral device, may load a very small number of fixed instructions into memory at a specific location, initialize at least one CPU, and then point the CPU to the instructions and start their execution. These instructions typically start an input operation from some peripheral device (which may be switch-selectable by the operator). Other systems may send hardware commands directly to peripheral devices or I/O controllers that cause an extremely simple input operation (such as \"read sector zero of the system device into memory starting at location 1000\") to be carried out, effectively loading a small number of boot loader instructions into memory; a completion signal from the I/O device may then be used to start execution of the instructions by the CPU.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Smaller computers often use less flexible but more automatic boot loader mechanisms to ensure that the computer starts quickly and with a predetermined software configuration. In many desktop computers, for example, the bootstrapping process begins with the CPU executing software contained in ROM (for example, the BIOS of an IBM PC) at a predefined address (some CPUs, including the Intel x86 series are designed to execute this software after reset without outside help). This software contains rudimentary functionality to search for devices eligible to participate in booting, and load a small program from a special section (most commonly the boot sector) of the most promising device, typically starting at a fixed entry point such as the start of the sector.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 4473, 15032, 15063, 216381, 1569732 ], "anchor_spans": [ [ 316, 320 ], [ 327, 333 ], [ 391, 401 ], [ 649, 660 ], [ 722, 733 ] ] }, { "plaintext": "Boot loaders may face peculiar constraints, especially in size; for instance, on the IBM PC and compatibles, the boot code must fit in the Master Boot Record (MBR) and the Partition Boot Record (PBR), which in turn are limited to a single sector; on the IBM System/360, the size is limited by the IPL medium, e.g., card size, track size.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 24782330, 5364422, 29294, 24420 ], "anchor_spans": [ [ 139, 157 ], [ 172, 193 ], [ 254, 268 ], [ 315, 319 ] ] }, { "plaintext": "On systems with those constraints, the first program loaded into RAM may not be sufficiently large to load the operating system and, instead, must load another, larger program. The first program loaded into RAM is called a first-stage boot loader, and the program it loads is called a second-stage boot loader.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Examples of first-stage (Hardware initialization stage) bootloaders include BIOS, UEFI, coreboot, Libreboot and Das U-Boot. On the IBM PC, the boot loader in the Master Boot Record (MBR) and the Partition Boot Record (PBR) was coded to require at least 32KB (later expanded to 64KB) of system memory and only use instructions supported by the original 8088/8086 processors.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 4473, 866065, 1556246, 43304468, 4412616, 24782330, 5364422, 15064, 15063 ], "anchor_spans": [ [ 76, 80 ], [ 82, 86 ], [ 88, 96 ], [ 98, 107 ], [ 112, 122 ], [ 162, 180 ], [ 195, 216 ], [ 352, 356 ], [ 357, 361 ] ] }, { "plaintext": "Second-stage (OS initialization stage) boot loaders, such as GNU GRUB, rEFInd, BOOTMGR, Syslinux, NTLDR or iBoot, are not themselves operating systems, but are able to load an operating system properly and transfer execution to it; the operating system subsequently initializes itself and may load extra device drivers. The second-stage boot loader does not need drivers for its own operation, but may instead use generic storage access methods provided by system firmware such as the BIOS, UEFI or Open Firmware, though typically with restricted hardware functionality and lower performance.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 287817, 44703551, 5881986, 357460, 287844, 55034399, 9101, 209452 ], "anchor_spans": [ [ 61, 69 ], [ 71, 77 ], [ 79, 86 ], [ 88, 96 ], [ 98, 103 ], [ 107, 112 ], [ 304, 317 ], [ 499, 512 ] ] }, { "plaintext": "Many boot loaders (like GNU GRUB, rEFInd, Windows's BOOTMGR, Syslinux, and Windows NT/2000/XP's NTLDR) can be configured to give the user multiple booting choices. These choices can include different operating systems (for dual or multi-booting from different partitions or drives), different versions of the same operating system (in case a new version has unexpected problems), different operating system loading options (e.g., booting into a rescue or safe mode), and some standalone programs that can function without an operating system, such as memory testers (e.g., memtest86+), a basic shell (as in GNU GRUB), or even games (see List of PC Booter games). Some boot loaders can also load other boot loaders; for example, GRUB loads BOOTMGR instead of loading Windows directly. Usually a default choice is preselected with a time delay during which a user can press a key to change the choice; after this delay, the default choice is automatically run so normal booting can occur without interaction.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 494756, 1850414, 695989, 24421213 ], "anchor_spans": [ [ 223, 244 ], [ 455, 464 ], [ 573, 583 ], [ 637, 660 ] ] }, { "plaintext": "The boot process can be considered complete when the computer is ready to interact with the user, or the operating system is capable of running system programs or application programs.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Many embedded systems must boot immediately. For example, waiting a minute for a digital television or a GPS navigation device to start is generally unacceptable. Therefore, such devices have software systems in ROM or flash memory so the device can begin functioning immediately; little or no loading is necessary, because the loading can be precomputed and stored on the ROM when the device is made.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 46630, 628485, 17800413, 50595 ], "anchor_spans": [ [ 5, 20 ], [ 81, 99 ], [ 105, 126 ], [ 219, 231 ] ] }, { "plaintext": "Large and complex systems may have boot procedures that proceed in multiple phases until finally the operating system and other programs are loaded and ready to execute. Because operating systems are designed as if they never start or stop, a boot loader might load the operating system, configure itself as a mere process within that system, and then irrevocably transfer control to the operating system. The boot loader then terminates normally as any other process would.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Most computers are also capable of booting over a computer network. In this scenario, the operating system is stored on the disk of a server, and certain parts of it are transferred to the client using a simple protocol such as the Trivial File Transfer Protocol (TFTP). After these parts have been transferred, the operating system takes over the control of the booting process.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 4122592, 42116, 52806 ], "anchor_spans": [ [ 50, 66 ], [ 134, 140 ], [ 232, 262 ] ] }, { "plaintext": "As with the second-stage boot loader, network booting begins by using generic network access methods provided by the network interface's boot ROM, which typically contains a Preboot Execution Environment (PXE) image. No drivers are required, but the system functionality is limited until the operating system kernel and drivers are transferred and started. As a result, once the ROM-based booting has completed it is entirely possible to network boot into an operating system that itself does not have the ability to use the network interface.", "section_idx": 2, "section_name": "Modern boot loaders", "target_page_ids": [ 432253 ], "anchor_spans": [ [ 174, 203 ] ] }, { "plaintext": "The boot device is the device from which the operating system is loaded. A modern PC's UEFI or BIOS firmware supports booting from various devices, typically a local solid state drive or hard disk drive via the GPT or Master Boot Record (MBR) on such a drive or disk, an optical disc drive (using El Torito), a USB mass storage device (FTL-based flash drive, SD card or multi-media card slot, USB hard disk drive, USB optical disc drive, etc.), or a network interface card (using PXE). Older, less common BIOS-bootable devices include floppy disk drives, Zip drives, and LS-120 drives.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 866065, 4473, 7366298, 13777, 2543892, 24782330, 299592, 15145, 32073, 455719, 28319458, 315794, 5367049, 432253, 304361, 278025, 271759 ], "anchor_spans": [ [ 87, 91 ], [ 95, 99 ], [ 166, 183 ], [ 187, 202 ], [ 211, 214 ], [ 218, 236 ], [ 271, 289 ], [ 297, 306 ], [ 311, 314 ], [ 315, 327 ], [ 336, 339 ], [ 359, 366 ], [ 370, 391 ], [ 480, 483 ], [ 535, 553 ], [ 555, 564 ], [ 571, 577 ] ] }, { "plaintext": "Typically, the system firmware (UEFI or BIOS) will allow the user to configure a boot order. If the boot order is set to \"first, the DVD drive; second, the hard disk drive\", then the firmware will try to boot from the DVD drive, and if this fails (e.g. because there is no DVD in the drive), it will try to boot from the local hard disk drive.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For example, on a PC with Windows installed on the hard drive, the user could set the boot order to the one given above, and then insert a Linux Live CD in order to try out Linux without having to install an operating system onto the hard drive. This is an example of dual booting, in which the user chooses which operating system to start after the computer has performed its Power-on self-test (POST). In this example of dual booting, the user chooses by inserting or removing the DVD from the computer, but it is more common to choose which operating system to boot by selecting from a boot manager menu on the selected device, by using the computer keyboard to select from a BIOS or UEFI Boot Menu, or both; the Boot Menu is typically entered by pressing or keys during the POST; the BIOS Setup is typically entered by pressing or keys during the POST.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 18890, 6097297, 331137, 6097297, 494756, 1699425, 632068, 4473, 866065, 4473 ], "anchor_spans": [ [ 26, 33 ], [ 139, 144 ], [ 145, 152 ], [ 173, 178 ], [ 268, 280 ], [ 377, 395 ], [ 589, 601 ], [ 679, 683 ], [ 687, 691 ], [ 790, 800 ] ] }, { "plaintext": "Several devices are available that enable the user to quick-boot into what is usually a variant of Linux for various simple tasks such as Internet access; examples are Splashtop and Latitude ON.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 13621776, 18934136 ], "anchor_spans": [ [ 168, 177 ], [ 182, 193 ] ] }, { "plaintext": "Upon starting, an IBM-compatible personal computer's x86 CPU, executes in real mode, the instruction located at reset vector (the physical memory address on 16-bit x86 processors and on 32-bit and 64-bit x86 processors), usually pointing to the firmware (UEFI or BIOS) entry point inside the ROM. This memory location typically contains a jump instruction that transfers execution to the location of the firmware (UEFI or BIOS) start-up program. This program runs a power-on self-test (POST) to check and initialize required devices such as main memory (DRAM), the PCI bus and the PCI devices (including running embedded Option ROMs). One of the most involved steps is setting up DRAM over SPD, further complicated by the fact that at this point memory is very limited.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 34198, 79823, 1775060, 866065, 4473, 866065, 4473, 1699425, 5300, 74567, 1766857, 2508638 ], "anchor_spans": [ [ 53, 56 ], [ 74, 83 ], [ 112, 124 ], [ 257, 261 ], [ 265, 269 ], [ 416, 420 ], [ 424, 428 ], [ 468, 486 ], [ 543, 554 ], [ 556, 560 ], [ 623, 633 ], [ 692, 695 ] ] }, { "plaintext": "After initializing required hardware, the firmware (UEFI or BIOS) goes through a pre-configured list of non-volatile storage devices (\"boot device sequence\") until it finds one that is bootable. A bootable MBR device is defined as one that can be read from, and where the last two bytes of the first sector contain the little-endian word , found as byte sequence , on disk (also known as the MBR boot signature), or where it is otherwise established that the code inside the sector is executable on x86 PCs.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 866065, 4473, 780629, 43026, 1613344, 24782330 ], "anchor_spans": [ [ 52, 56 ], [ 60, 64 ], [ 104, 132 ], [ 319, 332 ], [ 333, 337 ], [ 393, 411 ] ] }, { "plaintext": "Once the BIOS has found a bootable device it loads the boot sector to linear address (usually segment:offset :, but some BIOSes erroneously use :) and transfers execution to the boot code. In the case of a hard disk, this is referred to as the Master Boot Record (MBR). The conventional MBR code checks the MBR's partition table for a partition set as bootable (the one with active flag set). If an active partition is found, the MBR code loads the boot sector code from that partition, known as Volume Boot Record (VBR), and executes it. The MBR boot code is often operating-system specific.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 150178, 3240434, 24782330, 26257728, 216381, 5364422 ], "anchor_spans": [ [ 95, 102 ], [ 103, 109 ], [ 245, 263 ], [ 400, 416 ], [ 450, 461 ], [ 497, 515 ] ] }, { "plaintext": "The boot sector code is the first-stage boot loader. It is located on fixed disks and removable drives, and must fit into the first 446 bytes of the Master Boot Record in order to leave room for the default 64-byte partition table with four partition entries and the two-byte boot signature, which the BIOS requires for a proper boot loader or even less, when additional features like more than four partition entries (up to 16 with 16 bytes each), a disk signature (6 bytes), a disk timestamp (6 bytes), an Advanced Active Partition (18 bytes) or special multi-boot loaders have to be supported as well in some environments. In floppy and superfloppy Volume Boot Records, up to 59 bytes are occupied for the Extended BIOS Parameter Block on FAT12 and FAT16 volumes since DOS 4.0, whereas the FAT32 EBPB introduced with DOS 7.1 requires even 87 bytes, leaving only 423 bytes for the boot loader when assuming a sector size of 512 bytes. Microsoft boot sectors therefore traditionally imposed certain restrictions on the boot process, for example, the boot file had to be located at a fixed position in the root directory of the file system and stored as consecutive sectors, conditions taken care of by the command and slightly relaxed in later versions of DOS. The boot loader was then able to load the first three sectors of the file into memory, which happened to contain another embedded boot loader able to load the remainder of the file into memory. When Microsoft added LBA and FAT32 support, they even switched to a boot loader reaching over two physical sectors and using 386 instructions for size reasons. At the same time other vendors managed to squeeze much more functionality into a single boot sector without relaxing the original constraints on only minimal available memory (32KB) and processor support (). For example, DR-DOS boot sectors are able to locate the boot file in the FAT12, FAT16 and FAT32 file system, and load it into memory as a whole via CHS or LBA, even if the file is not stored in a fixed location and in consecutive sectors.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 13777, 891379, 3365, 24782330, 55380, 24782330, 24782330, 24782330, 24782330, 494756, 10891, 32179965, 5364422, 1092500, 53045, 53045, 53045, 404839, 1552884 ], "anchor_spans": [ [ 70, 80 ], [ 86, 101 ], [ 136, 141 ], [ 149, 167 ], [ 215, 230 ], [ 276, 290 ], [ 452, 466 ], [ 480, 494 ], [ 509, 534 ], [ 557, 567 ], [ 630, 636 ], [ 641, 652 ], [ 653, 671 ], [ 710, 739 ], [ 743, 748 ], [ 753, 758 ], [ 794, 799 ], [ 1479, 1482 ], [ 1974, 1977 ] ] }, { "plaintext": "The VBR is often OS-specific; however, its main function is to load and execute the operating system boot loader file (such as or ), which is the second-stage boot loader, from an active partition. Then the boot loader loads the OS kernel from the storage device.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 21346982 ], "anchor_spans": [ [ 230, 239 ] ] }, { "plaintext": "If there is no active partition, or the active partition's boot sector is invalid, the MBR may load a secondary boot loader which will select a partition (often via user input) and load its boot sector, which usually loads the corresponding operating system kernel. In some cases, the MBR may also attempt to load secondary boot loaders before trying to boot the active partition. If all else fails, it should issue an INT 18h BIOS interrupt call (followed by an INT 19h just in case INT 18h would return) in order to give back control to the BIOS, which would then attempt to boot off other devices, attempt a remote boot via network.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 217469, 1260095, 8002258 ], "anchor_spans": [ [ 419, 422 ], [ 427, 446 ], [ 611, 622 ] ] }, { "plaintext": "Many modern systems (Intel Macs and newer PCs) use UEFI.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 3698317, 18457137, 866065 ], "anchor_spans": [ [ 21, 30 ], [ 42, 45 ], [ 51, 55 ] ] }, { "plaintext": "Unlike BIOS, UEFI (not Legacy boot via CSM) does not rely on boot sectors, UEFI system loads the boot loader (EFI application file in USB disk or in the EFI System Partition) directly, and the OS kernel is loaded by the boot loader.", "section_idx": 3, "section_name": "Personal computers (PC)", "target_page_ids": [ 400414, 5366082 ], "anchor_spans": [ [ 134, 142 ], [ 153, 173 ] ] }, { "plaintext": "Many modern CPUs, SoCs and microcontrollers (for example, TI OMAP) or sometimes even digital signal processors (DSPs) may have boot ROM integrated directly into their silicon, so such a processor can perform a simple boot sequence on its own and load boot programs (firmware or software) from boot sources such as NAND flash or eMMC. It is difficult to hardwire all the required logic for handling such devices, so an integrated boot ROM is used instead in such scenarios. Also, a boot ROM may be able to load a boot loader or diagnostic program via serial interfaces like UART, SPI, USB and so on. This feature is often used for system recovery purposes, or it could also be used for initial non-volatile memory programming when there is no software available in the non-volatile memory yet. Many modern microcontrollers (e.g. flash memory controller on some USB flash drives) have firmware ROM integrated directly into their silicon.", "section_idx": 4, "section_name": "Other kinds of boot sequences", "target_page_ids": [ 47768, 1249322, 154505, 75008, 340476, 32073, 400414 ], "anchor_spans": [ [ 58, 60 ], [ 61, 65 ], [ 85, 110 ], [ 573, 577 ], [ 579, 582 ], [ 584, 587 ], [ 860, 875 ] ] }, { "plaintext": "Some embedded system designs may also include an intermediary boot sequence step. For example, Das U-Boot may be split into two stages: the platform would load a small SPL (Secondary Program Loader), which is a stripped-down version of U-Boot, and the SPL would do some initial hardware configuration (e.g. DRAM initialization using CPU cache as RAM) and load the larger, fully featured version of U-Boot.", "section_idx": 4, "section_name": "Other kinds of boot sequences", "target_page_ids": [ 46630, 4412616, 74567 ], "anchor_spans": [ [ 5, 20 ], [ 95, 105 ], [ 307, 311 ] ] }, { "plaintext": "It is also possible to take control of a system by using a hardware debug interface such as JTAG. Such an interface may be used to write the boot loader program into bootable non-volatile memory (e.g. flash) by instructing the processor core to perform the necessary actions to program non-volatile memory. Alternatively, the debug interface may be used to upload some diagnostic or boot code into RAM, and then to start the processor core and instruct it to execute the uploaded code. This allows, for example, the recovery of embedded systems where no software remains on any supported boot device, and where the processor does not have any integrated boot ROM. JTAG is a standard and popular interface; many CPUs, microcontrollers and other devices are manufactured with JTAG interfaces (as of 2009).", "section_idx": 4, "section_name": "Other kinds of boot sequences", "target_page_ids": [ 638112 ], "anchor_spans": [ [ 92, 96 ] ] }, { "plaintext": "Some microcontrollers provide special hardware interfaces which cannot be used to take arbitrary control of a system or directly run code, but instead they allow the insertion of boot code into bootable non-volatile memory (like flash memory) via simple protocols. Then at the manufacturing phase, such interfaces are used to inject boot code (and possibly other code) into non-volatile memory. After system reset, the microcontroller begins to execute code programmed into its non-volatile memory, just like usual processors are using ROMs for booting. Most notably this technique is used by Atmel AVR microcontrollers, and by others as well. In many cases such interfaces are implemented by hardwired logic. In other cases such interfaces could be created by software running in integrated on-chip boot ROM from GPIO pins.", "section_idx": 4, "section_name": "Other kinds of boot sequences", "target_page_ids": [ 100290, 1531568 ], "anchor_spans": [ [ 593, 602 ], [ 814, 818 ] ] }, { "plaintext": "Most DSPs have a serial mode boot, and a parallel mode boot, such as the host port interface (HPI boot).", "section_idx": 4, "section_name": "Other kinds of boot sequences", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In case of DSPs there is often a second microprocessor or microcontroller present in the system design, and this is responsible for overall system behavior, interrupt handling, dealing with external events, user interface, etc. while the DSP is dedicated to signal processing tasks only. In such systems the DSP could be booted by another processor which is sometimes referred as the host processor (giving name to a Host Port). Such a processor is also sometimes referred as the master, since it usually boots first from its own memories and then controls overall system behavior, including booting of the DSP, and then further controlling the DSP's behavior. The DSP often lacks its own boot memories and relies on the host processor to supply the required code instead. The most notable systems with such a design are cell phones, modems, audio and video players and so on, where a DSP and a CPU/microcontroller are co-existing.", "section_idx": 4, "section_name": "Other kinds of boot sequences", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Many FPGA chips load their configuration from an external serial EEPROM (\"configuration ROM\") on power-up.", "section_idx": 4, "section_name": "Other kinds of boot sequences", "target_page_ids": [ 10969, 50597 ], "anchor_spans": [ [ 5, 9 ], [ 65, 71 ] ] }, { "plaintext": " Boot disk", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 304361 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Bootkit", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 223942 ], "anchor_spans": [ [ 1, 8 ] ] }, { "plaintext": " Comparison of boot loaders", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 10077148 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Linux startup process", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 10439244 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Macintosh startup", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 28195927 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Microreboot", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 1169479 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Multi boot", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 494756 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Network booting", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 8002258 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " RedBoot", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 2676624 ], "anchor_spans": [ [ 1, 8 ] ] }, { "plaintext": " Self-booting disk", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 7048668 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Windows startup process", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 8669692 ], "anchor_spans": [ [ 1, 24 ] ] } ]

[ "Booting" ]

[ "booting up", "boot", "boot process", "booting a computer", "computer boot" ]

[ { "plaintext": "A common carrier in common law countries (corresponding to a public carrier in some civil law systems, usually called simply a carrier) is a person or company that transports goods or people for any person or company and is responsible for any possible loss of the goods during transport. A common carrier offers its services to the general public under license or authority provided by a regulatory body, which has usually been granted \"ministerial authority\" by the legislation that created it. The regulatory body may create, interpret, and enforce its regulations upon the common carrier (subject to judicial review) with independence and finality as long as it acts within the bounds of the enabling legislation.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5254, 1048798, 580039, 1210255, 2782814, 23042843 ], "anchor_spans": [ [ 20, 30 ], [ 84, 93 ], [ 175, 180 ], [ 224, 235 ], [ 389, 404 ], [ 604, 619 ] ] }, { "plaintext": "A common carrier (also called a public carrier in British English) is distinguished from a contract carrier, which is a carrier that transports goods for only a certain number of clients and that can refuse to transport goods for anyone else, and from a private carrier. A common carrier holds itself out to provide service to the general public without discrimination (to meet the needs of the regulator's quasi judicial role of impartiality toward the public's interest) for the \"public convenience and necessity.\" A common carrier must further demonstrate to the regulator that it is \"fit, willing, and able\" to provide those services for which it is granted authority. Common carriers typically transport persons or goods according to defined and published routes, time schedules, and rate tables upon the approval of regulators. Public airlines, railroads, bus lines, taxicab companies, phone companies, internet service providers, cruise ships, motor carriers (i.e., canal operating companies, trucking companies), and other freight companies generally operate as common carriers. Under US law, an ocean freight forwarder cannot act as a common carrier.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 6742891, 307834, 8900, 1942, 25715, 4146, 22026933, 47005, 100245, 314855, 5623, 4177, 4733237, 18842359, 3742114 ], "anchor_spans": [ [ 254, 269 ], [ 331, 345 ], [ 354, 368 ], [ 841, 848 ], [ 851, 859 ], [ 862, 870 ], [ 873, 880 ], [ 892, 907 ], [ 909, 935 ], [ 937, 948 ], [ 973, 978 ], [ 979, 998 ], [ 1031, 1048 ], [ 1104, 1109 ], [ 1110, 1127 ] ] }, { "plaintext": "The term common carrier is a common law term and is seldom used in Continental Europe because it has no exact equivalent in civil-law systems. In Continental Europe, the functional equivalent of a common carrier is referred to as a public carrier or simply as a carrier. However, public carrier in Continental Europe is different from public carrier in British English in which it is a synonym for contract carrier.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Although common carriers generally transport people or goods, in the United States the term may also refer to telecommunications service providers and public utilities. In certain U.S. states, amusement parks that operate roller coasters and comparable rides have been found to be common carriers; a famous example is Disneyland.", "section_idx": 1, "section_name": "General", "target_page_ids": [ 580039, 47005, 171136, 18618239, 137327, 137471, 15937788 ], "anchor_spans": [ [ 55, 59 ], [ 110, 145 ], [ 151, 167 ], [ 180, 190 ], [ 193, 207 ], [ 222, 236 ], [ 318, 328 ] ] }, { "plaintext": "Regulatory bodies may also grant carriers the authority to operate under contract with their customers instead of under common carrier authority, rates, schedules and rules. These regulated carriers, known as contract carriers, must demonstrate that they are \"fit, willing and able\" to provide service, according to standards enforced by the regulator. However, contract carriers are specifically not required to demonstrate that they will operate for the \"public convenience and necessity.\" A contract carrier may be authorized to provide service over either fixed routes and schedules, i.e., as regular route carrier or on an ad hoc basis as an irregular route carrier.", "section_idx": 1, "section_name": "General", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "It should be mentioned that the carrier refers only to the person (legal or physical) that enters into a contract of carriage with the shipper. The carrier does not necessarily have to own or even be in the possession of a means of transport. Unless otherwise agreed upon in the contract, the carrier may use whatever means of transport approved in its operating authority, as long as it is the most favorable from the cargo interests' point of view. The carriers' duty is to get the goods to the agreed destination within the agreed time or within reasonable time.", "section_idx": 1, "section_name": "General", "target_page_ids": [ 9932845, 361406, 396550 ], "anchor_spans": [ [ 67, 72 ], [ 76, 84 ], [ 419, 424 ] ] }, { "plaintext": "The person that is physically transporting the goods on a means of transport is referred to as the \"actual carrier.\" When a carrier subcontracts with another provider, such as an independent contractor or a third-party carrier, the common carrier is said to be providing \"substituted service.\" The same person may hold both common carrier and contract carrier authority. In the case of a rail line in the US, the owner of the property is said to retain a \"residual common carrier obligation,\" unless otherwise transferred (such as in the case of a commuter rail system, where the authority operating passenger trains may acquire the property but not this obligation from the former owner), and must operate the line if service is terminated. ", "section_idx": 1, "section_name": "General", "target_page_ids": [ 314993, 578491, 6286, 15461460 ], "anchor_spans": [ [ 179, 201 ], [ 388, 397 ], [ 548, 561 ], [ 600, 616 ] ] }, { "plaintext": "In contrast, private carriers are not licensed to offer a service to the public. Private carriers generally provide transport on an irregular or ad hoc basis for their owners.", "section_idx": 1, "section_name": "General", "target_page_ids": [ 6742891 ], "anchor_spans": [ [ 13, 28 ] ] }, { "plaintext": "Carriers were very common in rural areas prior to motorised transport. Regular services by horse-drawn vehicles would ply to local towns, taking goods to market or bringing back purchases for the village. If space permitted, passengers could also travel.", "section_idx": 1, "section_name": "General", "target_page_ids": [ 3932408, 53509 ], "anchor_spans": [ [ 91, 111 ], [ 196, 203 ] ] }, { "plaintext": "Cases have also established limitations to the common carrier designation. In a case concerning a hot air balloon, Grotheer v. Escape Adventures, Inc., the court affirmed a hot air balloon was not a common carrier, holding the key inquiry in determining whether or not a transporter can be classified as a common carrier is whether passengers expect the transportation to be safe because the operator is reasonably capable of controlling the risk of injury.", "section_idx": 1, "section_name": "General", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the United States, telecommunications carriers are regulated by the Federal Communications Commission under title II of the Communications Act of 1934.", "section_idx": 2, "section_name": "Telecommunications", "target_page_ids": [ 33094374, 55974, 66040 ], "anchor_spans": [ [ 22, 40 ], [ 71, 104 ], [ 127, 153 ] ] }, { "plaintext": "The Telecommunications Act of 1996 made extensive revisions to the \"Title II\" provisions regarding common carriers and repealed the judicial 1982 AT&T consent decree (often referred to as the Modification of Final Judgment) that effectuated the breakup of AT&T's Bell System. Further, the Act gives telephone companies the option of providing video programming on a common carrier basis or as a conventional cable television operator. If it chooses the former, the telephone company will face less regulation but will also have to comply with FCC regulations requiring what the Act refers to as \"open video systems\". The Act generally bars, with certain exceptions including most rural areas, acquisitions by telephone companies of more than a 10 percent interest in cable operators (and vice versa) and joint ventures between telephone companies and cable systems serving the same areas.", "section_idx": 2, "section_name": "Telecommunications", "target_page_ids": [ 196010, 41377, 21347591 ], "anchor_spans": [ [ 4, 34 ], [ 192, 222 ], [ 263, 274 ] ] }, { "plaintext": "Using provisions of the Communications Act of 1934, the FCC classified Internet service providers as common carriers, effective June 12, 2015, for the purpose of enforcing net neutrality. Before that time, the Good Samaritan provision of the Communications Decency Act established immunity from liability for third party content on grounds of libel or slander, and the DMCA established that ISPs that comply with the DMCA would not be liable for the copyright violations of third parties on their network. On December 14, 2017, under a new presidential administration, the FCC reversed its own rules on net neutrality, essentially revoking common carrier status as a requirement for internet service providers. The U.S. Senate narrowly passed a non-binding resolution aiming to reverse the FCC's decision and restore FCC's net neutrality rules.", "section_idx": 2, "section_name": "Telecommunications", "target_page_ids": [ 66040, 100245, 1398166, 39296, 20648089 ], "anchor_spans": [ [ 24, 50 ], [ 71, 97 ], [ 172, 186 ], [ 243, 269 ], [ 370, 374 ] ] }, { "plaintext": "In the United States, many oil, gas and CO2 pipelines are common carriers. The Federal Energy Regulatory Commission (FERC) regulates rates charged and other tariff terms imposed by interstate common carrier pipelines. Intrastate common carrier pipeline tariffs are often regulated by state agencies. The US and many states have delegated the power of eminent domain to common carrier gas pipelines.", "section_idx": 3, "section_name": "Pipelines", "target_page_ids": [ 5906, 51111, 56976, 144089 ], "anchor_spans": [ [ 40, 43 ], [ 44, 53 ], [ 79, 115 ], [ 351, 365 ] ] }, { "plaintext": "Common carriers are subject to special laws and regulations that differ depending on the means of transport used, e.g. sea carriers are often governed by quite different rules from road carriers or railway carriers. In common law jurisdictions as well as under international law, a common carrier is absolutely liable for goods carried by it, with four exceptions:", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [ 8195726 ], "anchor_spans": [ [ 261, 278 ] ] }, { "plaintext": " An act of nature", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " An act of the public enemies", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Fault or fraud by the shipper", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " An inherent defect in the goods", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A sea carrier may also, according to the Hague-Visby Rules, escape liability on other grounds than the above-mentioned, e.g. a sea carrier is not liable for damages to the goods if the damage is the result of a fire on board the ship or the result of a navigational error committed by the ship's master or other crewmember.", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [ 12201075 ], "anchor_spans": [ [ 41, 58 ] ] }, { "plaintext": "Carriers typically incorporate further exceptions into a contract of carriage, often specifically claiming not to be a common carrier.", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [ 4611545 ], "anchor_spans": [ [ 57, 77 ] ] }, { "plaintext": "An important legal requirement for common carrier as public provider is that it cannot discriminate, that is refuse the service unless there is some compelling reason. As of 2007, the status of Internet service providers as common carriers and their rights and responsibilities is widely debated (network neutrality).", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [ 1398166 ], "anchor_spans": [ [ 297, 315 ] ] }, { "plaintext": "The term common carrier does not exist in continental Europe but is distinctive to common law systems, particularly law systems in the US.", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In Ludditt v Ginger Coote Airways the Privy Council (Lord Macmillan, Lord Wright, Lord Porter and Lord Simonds) held the liability of a public or common carrier of passengers is only to carry with due care. This is more limited than that of a common carrier of goods. The complete freedom of a carrier of passengers at common law to make such contracts as he thinks fit was not curtailed by the Railway and Canal Traffic Act 1854, and a specific contract that enlarges, diminishes or excludes his duty to take care (e.g., by a condition that the passenger travels \"at his own risk against all casualties\") cannot be pronounced to be unreasonable if the law authorises it. There was nothing in the provisions of the Canadian Transport Act 1938 section 25 that would invalidate a provision excluding liability. Grand Trunk Railway Co of Canada v Robinson [1915] A.C. 740 was followed and Peek v North Staffordshire Railway 11 E.R. 1109 was distinguished.", "section_idx": 4, "section_name": "Legal implications", "target_page_ids": [ 652321, 13635548 ], "anchor_spans": [ [ 38, 51 ], [ 395, 429 ] ] }, { "plaintext": " Cybertelecom Common Carrier", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " FCC Wireline Competition Bureau, formerly the Common Carrier Bureau", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Communicatons Act of 1934 including definition of a Common Carrier, Title II from FCC.gov", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Traffic_management", "Freight_transport", "International_law", "Legal_terminology", "Net_neutrality", "Rail_transport_operations", "Tort_law" ]

[ "common carrier", "public carrier" ]

[ { "plaintext": "In telecommunications, common control is a principle of switching telephone calls in an automatic telephone exchange that employs shared control equipment which is attached to the circuit of a call only for the duration of establishing or otherwise controlling the call. Thus, such control equipment need only be provided in as few units to satisfy overall exchange traffic, rather than being duplicated for every subscriber line.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 406703, 26668156 ], "anchor_spans": [ [ 3, 21 ], [ 66, 80 ], [ 98, 116 ] ] }, { "plaintext": "In contrast, direct control systems have subsystems for call control that are an integral part of the switching network. Strowger exchanges are usually direct control systems, whereas crossbar, and electronic exchanges (including all stored program control systems) are common control systems. Common control is also known as indirect control or register control.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 179918, 7092252 ], "anchor_spans": [ [ 121, 138 ], [ 234, 256 ] ] }, { "plaintext": "Early semi-mechanical installations with common control components existed, for example rotary systems in Sweden and France in 1915, and the first panel switches in Newark, New Jersey, also in 1915. The first large-scale, fully automatic, common control switching system deployed in commercial production service was the ATlantic central office in Omaha, Nebraska, a panel system cut over on December 10, 1921. Other panel offices for Kansas City and New York CIty (PENnsylvania) were in planning at the same time and opened shortly after.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 17248101, 50350318 ], "anchor_spans": [ [ 88, 94 ], [ 147, 159 ] ] }, { "plaintext": "In 1922, common control was introduced in Strowger-type step-by-step systems, resulting in the first installations of Director systems in Havanna, Cuba in 1924, and in London, England in 1927.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 179918, 652431 ], "anchor_spans": [ [ 42, 55 ], [ 118, 126 ] ] }, { "plaintext": "By the mid-1920s, common control ideas had extended to include marker systems for testing for idle trunks.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 3857668, 593233 ], "anchor_spans": [ [ 63, 69 ], [ 99, 105 ] ] }, { "plaintext": "During the 1960s, common control exchanges became stored program control exchanges, and by the 1970s they used common-channel signaling in which the channels that are used for signaling are not used for message traffic (out of band signaling).", "section_idx": 1, "section_name": "History", "target_page_ids": [ 7092252, 378018, 41703, 41367 ], "anchor_spans": [ [ 50, 72 ], [ 111, 135 ], [ 176, 185 ], [ 203, 210 ] ] } ]

[ "Telephone_exchange_equipment" ]

[]

[ { "plaintext": "The Common Management Information Service (CMIS) is the service interface specified in ITU-T Recommendation X.710, ISO/IEC International Standard 9595 that is employed by OSI network elements for network management. It defines the service interface that is implemented by the Common Management Information Protocol (CMIP) as specified in ITU-T Recommendation X.711, ISO/IEC International Standard 9596-1. CMIS is part of the Open Systems Interconnection (OSI) body of international network standards.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 902125, 22747 ], "anchor_spans": [ [ 276, 314 ], [ 425, 453 ] ] }, { "plaintext": "Note the term CMIP is sometimes used erroneously when CMIS is intended. CMIS/CMIP is most often used in telecommunication applications, in other areas SNMP has become more popular.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 41710 ], "anchor_spans": [ [ 104, 121 ], [ 151, 155 ] ] }, { "plaintext": "The following services are made available by the Common Management Information Service Element (CMISE) to allow management of network elements:", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-CREATE – Create an instance of a managed object", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-DELETE – Delete an instance of a managed object", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-GET – Request managed object attributes (for one object or a set of objects)", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-CANCEL-GET – Cancel an outstanding GET request", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-SET – Set managed object attributes", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-ACTION – Request an action to be performed on a managed object", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-EVENT-REPORT – Send events occurring on managed objects", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "To transfer management information between open systems using CMIS/CMIP, peer connections, i.e., associations, must be established. This requires the establishment of an Application layer association, a Session layer connection, a Transport layer connection, and, depending on supporting communications technology, Network layer and Link layer connections.", "section_idx": 1, "section_name": "Services", "target_page_ids": [ 4017168, 18985062, 172179, 142409, 346001, 146145, 33094374, 85024, 30862590 ], "anchor_spans": [ [ 3, 11 ], [ 23, 34 ], [ 170, 187 ], [ 203, 216 ], [ 217, 227 ], [ 231, 246 ], [ 288, 302 ], [ 315, 328 ], [ 333, 343 ] ] }, { "plaintext": "CMIS initially defined management association services but it was later decided these services could be provided by ACSE and these services were removed. Below is a list of these services which were subsequently removed from ISO 9595:", "section_idx": 1, "section_name": "Services", "target_page_ids": [ 1117728 ], "anchor_spans": [ [ 116, 120 ] ] }, { "plaintext": " M-INITIALIZE – Creates an association with (i.e. connects to) another CMISE", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-TERMINATE – Terminates an established connection", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " M-ABORT – Terminates the association in the case of an abnormal connection termination", "section_idx": 1, "section_name": "Services", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Common Management Information Protocol (CMIP)", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 902125 ], "anchor_spans": [ [ 0, 38 ] ] } ]

[ "Network_management" ]

[]

[ { "plaintext": "In telecommunications, communications blackouts are", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " a cessation of communications or communications capability, caused by a lack of power to a communications facility or to communications equipment.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 296636, 41132 ], "anchor_spans": [ [ 16, 30 ], [ 73, 86 ], [ 107, 115 ] ] }, { "plaintext": " a total lack of radio communications capability, caused by ionospheric anomalies, e.g., during strong auroral activity or during re-entry of a spacecraft into the Earth's atmosphere.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 15097, 37910 ], "anchor_spans": [ [ 60, 71 ], [ 144, 154 ] ] }, { "plaintext": "Uptime being a key goal of most communications networks, power supplies and backup generators are typically used to ensure high-reliability power.", "section_idx": 1, "section_name": "Technical failures", "target_page_ids": [ 279585, 46545, 41834, 2736308 ], "anchor_spans": [ [ 0, 6 ], [ 32, 54 ], [ 57, 71 ], [ 76, 92 ] ] }, { "plaintext": "Wireless networks may be subject to radio jamming; wired networks can be physically severed. Network design can also play a role in maintaining communications reliability; depending on the constraints in building a fiber-optic network, a self-healing ring topology may be used.", "section_idx": 1, "section_name": "Technical failures", "target_page_ids": [ 1838227, 1577061, 3372377, 335129 ], "anchor_spans": [ [ 36, 49 ], [ 95, 109 ], [ 217, 228 ], [ 240, 257 ] ] }, { "plaintext": "The communications blackouts that affect spacecraft re-entering the Earth's atmosphere, which are also known as radio blackouts, ionization blackouts, or reentry blackouts, are caused by an envelope of ionized air around the craft, created by the heat from the compression of the atmosphere by the craft. The ionized air interferes with radio signals. For the Mercury, Gemini, and Apollo spacecraft, such communications blackouts lasted for several minutes. Gemini 2, for example, endured such a blackout for four minutes, beginning at 9 minutes 5 seconds into the descent.", "section_idx": 2, "section_name": "Spacecraft reentry", "target_page_ids": [ 45294, 19812, 882736, 1461, 404290 ], "anchor_spans": [ [ 52, 86 ], [ 360, 367 ], [ 369, 375 ], [ 381, 387 ], [ 458, 466 ] ] }, { "plaintext": "For Apollo missions, the communications blackout was approximately three minutes long. For Apollo 16, for example, pre-advisory data (PAD) for re-entry listed the expected times for re-entry communications blackout to be from 0 minutes 16 seconds after entry interface to 3 minutes 33 seconds after entry interface (a total of 3 minutes 17 seconds). For the Apollo 13 mission, the blackout was much longer than normal because the flight path of the spacecraft was unexpectedly at a much shallower angle than normal. According to the mission log maintained by Gene Kranz, the Apollo 13 re-entry blackout lasted around 6 minutes, beginning at 142:39 and ending at 142:45, and was 1 minute 27 seconds longer than had been predicted.", "section_idx": 2, "section_name": "Spacecraft reentry", "target_page_ids": [ 1970, 1770, 407054 ], "anchor_spans": [ [ 91, 100 ], [ 358, 367 ], [ 559, 569 ] ] }, { "plaintext": "Communications blackouts for re-entry are not solely confined to entry into Earth's atmosphere. They apply to entry into any atmosphere where such ionization occurs around a craft. The Mars Pathfinder endured a 30-second communications blackout as it entered Mars' atmosphere, for example. The Huygens probe endured a communications blackout as it entered the atmosphere of Titan.", "section_idx": 2, "section_name": "Spacecraft reentry", "target_page_ids": [ 177323, 185083, 47402 ], "anchor_spans": [ [ 185, 200 ], [ 294, 307 ], [ 374, 379 ] ] }, { "plaintext": "Until the creation of the Tracking and Data Relay Satellite System (TDRSS), the Space Shuttle endured a 30-minute blackout. The TDRSS allowed the Shuttle to communicate by relay with a Tracking and Data Relay Satellite during re-entry, through a \"hole\" in the ionized air envelope at the tail end of the craft, created by the Shuttle's shape.", "section_idx": 2, "section_name": "Spacecraft reentry", "target_page_ids": [ 633269, 28189, 3766627 ], "anchor_spans": [ [ 26, 66 ], [ 80, 93 ], [ 185, 218 ] ] }, { "plaintext": "Radio blackouts on Earth caused by solar flares are measured by the National Oceanic and Atmospheric Administration on a scale from 1 (minor) to 5 (extreme).", "section_idx": 3, "section_name": "Space weather", "target_page_ids": [ 54648, 37876 ], "anchor_spans": [ [ 35, 46 ], [ 68, 115 ] ] }, { "plaintext": "Communications can also be lost when the Sun is blocking or behind one station in the same line of sight; Sun outages periodically interrupt communications with geosynchronous satellites. It is also a common problem for interplanetary space missions.", "section_idx": 4, "section_name": "Solar position", "target_page_ids": [ 26751, 2801765, 11869902, 10204411 ], "anchor_spans": [ [ 41, 44 ], [ 106, 116 ], [ 161, 185 ], [ 236, 250 ] ] }, { "plaintext": " Sudden ionospheric disturbance", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 5478196 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Sun outage", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 2801765 ], "anchor_spans": [ [ 1, 11 ] ] } ]

[ "Radio_frequency_propagation", "Telecommunications_engineering", "Technological_failures" ]

[]

[ { "plaintext": "In telecommunication, the term communications center has the following meanings: ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " An agency charged with the responsibility for handling and controlling communications traffic. The center normally includes a message center, and transmitting and receiving facilities.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 43081, 41367 ], "anchor_spans": [ [ 72, 86 ], [ 87, 94 ], [ 127, 134 ] ] }, { "plaintext": " A facility that (a) serves as a node for a communications network, (b) is equipped for technical control and maintenance of the circuits originating, transiting, or terminating at the node, (c) may contain message-center facilities, and (d) may serve as a gateway. Synonym comm center.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41132, 998116, 46545, 91191, 998116, 1338556 ], "anchor_spans": [ [ 3, 11 ], [ 33, 37 ], [ 44, 66 ], [ 110, 121 ], [ 185, 189 ], [ 257, 264 ] ] }, { "plaintext": "Network operations center", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 883983 ], "anchor_spans": [ [ 0, 25 ] ] } ]

[ "Telecommunications_buildings" ]

[ "communications centre", "communications node" ]

[ { "plaintext": "In telecommunication, the term communications deception has the following meanings:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " Deliberate transmission, retransmission, or alteration of communications to mislead an adversary's interpretation of the communications.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152 ], "anchor_spans": [ [ 12, 24 ] ] }, { "plaintext": " Use of devices, operations, and techniques with the intent of confusing or misleading the user of a communications link or a navigation system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2052479, 40996, 8286675 ], "anchor_spans": [ [ 91, 95 ], [ 116, 120 ], [ 137, 143 ] ] }, { "plaintext": "National Information Systems Security Glossary", "section_idx": 1, "section_name": "References", "target_page_ids": [ 1011395 ], "anchor_spans": [ [ 0, 46 ] ] } ]

[ "Military_communications", "Deception", "Phreaking", "Telephone_crimes" ]

[]

[ { "plaintext": "In telecommunication, communications-electronics (C-E) is the specialized field concerned with the use of electronic devices and systems for the acquisition or acceptance, processing, storage, display, analysis, protection, disposition, and transfer of information. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 155319, 5300, 18985062 ], "anchor_spans": [ [ 3, 20 ], [ 145, 156 ], [ 184, 191 ], [ 253, 264 ] ] }, { "plaintext": "C-E includes the wide range of responsibilities and actions relating to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Electronic devices and systems used in the transfer of ideas and perceptions;", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Electronic sensors and sensory systems used in the acquisition of information devoid of semantic influence;", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Electronic devices and systems intended to allow friendly forces to operate in hostile environments and to deny to hostile forces the effective use of electromagnetic resources.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Communication electronics radio equipment has been a rapidly growing industry for more than a century. Homeland Security in the USA is one of the reasons for the fast growth. Since the invention of the “solid state” transistor in the 1950s and the TTL (transistor-transistor logic) that led to the development of the IC (integrated circuit) in the 1960s the growth in the field of electronics has been phenomenal. As now witnessed in the “radio communications” field. The latest trend is to send conventional LMR (land-mobile-radio) signals over the Internet (Internet Protocol) this is called RoIP (Radio over Internet Protocol), which is just like VoIP (Voice over Internet Protocol) but uses the radio. By sending signals over the Internet it allows radios to be connected together all over the world. Hence: the “Communications Revolution”.", "section_idx": 1, "section_name": "Electronic Communications Equipment", "target_page_ids": [ 13485805, 42105, 30011, 47769, 15150, 15323, 3090397 ], "anchor_spans": [ [ 26, 41 ], [ 103, 120 ], [ 216, 226 ], [ 253, 280 ], [ 321, 339 ], [ 560, 577 ], [ 594, 598 ] ] }, { "plaintext": "Ingegneria delle telecomunicazioni", "section_idx": 1, "section_name": "Electronic Communications Equipment", "target_page_ids": [], "anchor_spans": [] } ]

[ "Communication_circuits", "Electronic_engineering" ]

[]

[ { "plaintext": "In telecommunications, communications protection is the application of communications security (COMSEC) measures to telecommunications systems in order to: (a) deny unauthorized access to sensitive unclassified information of value, (b) prevent disruption of telecommunications services, or (c) ensure the authenticity of information handled by telecommunications systems.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 40922, 40684, 18985062 ], "anchor_spans": [ [ 3, 20 ], [ 71, 94 ], [ 160, 184 ], [ 211, 222 ] ] } ]

[ "Military_communications" ]

[]

[ { "plaintext": "Communications security is the discipline of preventing unauthorized interceptors from accessing telecommunications in an intelligible form, while still delivering content to the intended recipients.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 28030850, 33094374 ], "anchor_spans": [ [ 0, 14 ], [ 97, 114 ] ] }, { "plaintext": "In the North Atlantic Treaty Organization culture, including United States Department of Defense culture, it is often referred to by the abbreviation COMSEC. The field includes cryptographic security, transmission security, emissions security and physical security of COMSEC equipment and associated keying material.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 21133, 1070569, 58725 ], "anchor_spans": [ [ 7, 41 ], [ 202, 223 ], [ 248, 265 ] ] }, { "plaintext": "COMSEC is used to protect both classified and unclassified traffic on military communications networks, including voice, video, and data. It is used for both analog and digital applications, and both wired and wireless links.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 252857, 252857, 2023546 ], "anchor_spans": [ [ 31, 41 ], [ 46, 58 ], [ 70, 93 ] ] }, { "plaintext": "Voice over secure internet protocol VOSIP has become the de facto standard for securing voice communication, replacing the need for ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Secure Terminal Equipment (STE) in much of NATO, including the U.S.A. USCENTCOM moved entirely to VOSIP in 2008.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 812389, 338482 ], "anchor_spans": [ [ 0, 25 ], [ 70, 79 ] ] }, { "plaintext": " Cryptographic security: The component of communications security that results from the provision of technically sound cryptosystems and their proper use. This includes ensuring message confidentiality and authenticity.", "section_idx": 1, "section_name": "Specialties", "target_page_ids": [ 18934432 ], "anchor_spans": [ [ 119, 132 ] ] }, { "plaintext": " Emission security (EMSEC): The protection resulting from all measures taken to deny unauthorized persons information of value that might be derived from communications systems and cryptographic equipment intercepts and the interception and analysis of compromising emanations from cryptographic—equipment, information systems, and telecommunications systems.", "section_idx": 1, "section_name": "Specialties", "target_page_ids": [ 184781 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Transmission security (TRANSEC): The component of communications security that results from the application of measures designed to protect transmissions from interception and exploitation by means other than cryptanalysis (e.g. frequency hopping and spread spectrum).", "section_idx": 1, "section_name": "Specialties", "target_page_ids": [ 1098290, 5715, 46890, 41734 ], "anchor_spans": [ [ 1, 22 ], [ 210, 223 ], [ 230, 247 ], [ 252, 267 ] ] }, { "plaintext": " Physical security: The component of communications security that results from all physical measures necessary to safeguard classified equipment, material, and documents from access thereto or observation thereof by unauthorized persons.", "section_idx": 1, "section_name": "Specialties", "target_page_ids": [ 58725, 40684 ], "anchor_spans": [ [ 83, 100 ], [ 175, 181 ] ] }, { "plaintext": "AKMS = the Army Key Management System", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "AEK = Algorithmic Encryption Key", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "CT3 = Common Tier 3", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "CCI = Controlled Cryptographic Item - equipment which contains COMSEC embedded devices", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 1639442 ], "anchor_spans": [ [ 6, 35 ] ] }, { "plaintext": "ACES = Automated Communications Engineering Software", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "DTD = Data Transfer Device", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 1044888 ], "anchor_spans": [ [ 6, 26 ] ] }, { "plaintext": "ICOM = Integrated COMSEC, e.g. a radio with built in encryption", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "TEK = Traffic Encryption Key", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 10294 ], "anchor_spans": [ [ 14, 24 ] ] }, { "plaintext": "TED = Trunk Encryption Device such as the WALBURN/KG family ", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "KEK = Key Encryption Key", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "KPK = Key production key", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "OWK = Over the Wire Key", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "OTAR = Over the Air Rekeying", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 2375255 ], "anchor_spans": [ [ 7, 28 ] ] }, { "plaintext": "LCMS = Local COMSEC Management Software", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "KYK-13 = Electronic Transfer Device", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 4013761 ], "anchor_spans": [ [ 0, 6 ] ] }, { "plaintext": "KOI-18 = Tape Reader General Purpose", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 4320975 ], "anchor_spans": [ [ 0, 6 ] ] }, { "plaintext": "KYX-15 = Electronic Transfer Device", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "KG-30 = family of COMSEC equipment", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "TSEC = Telecommunications Security (sometimes referred to in error transmission security or TRANSEC)", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "SOI = Signal operating instructions", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 14228380 ], "anchor_spans": [ [ 6, 35 ] ] }, { "plaintext": "SKL = Simple Key Loader", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 6055815 ], "anchor_spans": [ [ 6, 23 ] ] }, { "plaintext": "TPI = Two person integrity", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 2650801 ], "anchor_spans": [ [ 6, 26 ] ] }, { "plaintext": " STU-III (obsolete secure phone, replaced by STE)", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 794541 ], "anchor_spans": [ [ 1, 8 ] ] }, { "plaintext": " STE - Secure Terminal Equipment (secure phone)", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 812389 ], "anchor_spans": [ [ 7, 32 ] ] }, { "plaintext": "Types of COMSEC equipment:", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Crypto equipment: Any equipment that embodies cryptographic logic or performs one or more cryptographic functions (key generation, encryption, and authentication).", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [ 18934432 ], "anchor_spans": [ [ 47, 60 ] ] }, { "plaintext": " Crypto-ancillary equipment: Equipment designed specifically to facilitate efficient or reliable operation of crypto-equipment, without performing cryptographic functions itself.", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Crypto-production equipment: Equipment used to produce or load keying material", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Authentication equipment:", "section_idx": 2, "section_name": "Related terms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The Electronic Key Management System (EKMS) is a United States Department of Defense (DoD) key management, COMSEC material distribution, and logistics support system. The National Security Agency (NSA) established the EKMS program to supply electronic key to COMSEC devices in securely and timely manner, and to provide COMSEC managers with an automated system capable of ordering, generation, production, distribution, storage, security accounting, and access control.", "section_idx": 3, "section_name": "DoD Electronic Key Management System", "target_page_ids": [ 1042768, 7279897, 21939 ], "anchor_spans": [ [ 4, 36 ], [ 49, 84 ], [ 171, 195 ] ] }, { "plaintext": "The Army's platform in the four-tiered EKMS, AKMS, automates frequency management and COMSEC management operations. It eliminates paper keying material, hardcopy SOI, and associated time and resource-intensive courier distribution. It has 4 components:", "section_idx": 3, "section_name": "DoD Electronic Key Management System", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " LCMS provides automation for the detailed accounting required for every COMSEC account, and electronic key generation and distribution capability.", "section_idx": 3, "section_name": "DoD Electronic Key Management System", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ACES is the frequency management portion of AKMS. ACES has been designated by the Military Communications Electronics Board as the joint standard for use by all services in development of frequency management and cryptonet planning.", "section_idx": 3, "section_name": "DoD Electronic Key Management System", "target_page_ids": [ 4312667 ], "anchor_spans": [ [ 13, 33 ] ] }, { "plaintext": " CT3 with DTD software is in a fielded, ruggedized hand-held device that handles, views, stores, and loads SOI, Key, and electronic protection data. DTD provides an improved net-control device to automate crypto-net control operations for communications networks employing electronically keyed COMSEC equipment.", "section_idx": 3, "section_name": "DoD Electronic Key Management System", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " SKL is a hand-held PDA that handles, views, stores, and loads SOI, Key, and electronic protection data.", "section_idx": 3, "section_name": "DoD Electronic Key Management System", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "KMI is intended to replace the legacy Electronic Key Management System to provide a means for securely ordering, generating, producing, distributing, managing, and auditing cryptographic products (e.g., asymmetric keys, symmetric keys, manual cryptographic systems, and cryptographic applications). This system is currently being fielded by Major Commands and variants will be required for non-DoD Agencies with a COMSEC Mission.", "section_idx": 4, "section_name": "Key Management Infrastructure (KMI) Program", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Dynamic secrets", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 44253927 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Electronics technician (United States Navy)", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 31153640 ], "anchor_spans": [ [ 0, 43 ] ] }, { "plaintext": "Information security", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 15036 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Information warfare", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 144589 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": " List of telecommunications encryption terms", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 39352 ], "anchor_spans": [ [ 1, 44 ] ] }, { "plaintext": "NSA encryption systems", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 1042273 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "NSA product types", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 41829 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Operations security", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 3025124 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Secure communication", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 1467336 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Signals intelligence", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 29122 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Traffic analysis", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 480015 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "National Information Systems Security Glossary", "section_idx": 6, "section_name": "References", "target_page_ids": [ 1011395 ], "anchor_spans": [ [ 0, 46 ] ] }, { "plaintext": " Cryptography machines", "section_idx": 6, "section_name": "References", "target_page_ids": [], "anchor_spans": [] } ]

[ "Cryptography", "Military_communications", "Military_radio_systems", "Encryption_devices" ]

[]

[ { "plaintext": "In telecommunication, communications survivability is the ability of communications systems to continue to operate effectively under adverse conditions, though portions of the system may be damaged or destroyed. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 33094374, 8286675 ], "anchor_spans": [ [ 3, 20 ], [ 69, 83 ], [ 176, 182 ] ] }, { "plaintext": "Various methods may be used to maintain communications services, such as using alternate routing, different transmission media or methods, redundant equipment, and sites and equipment that are radiation hardened.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152, 1041641 ], "anchor_spans": [ [ 108, 120 ], [ 193, 211 ] ] } ]

[ "Telecommunications_engineering" ]

[]

[ { "plaintext": "A communications system or communication system is a collection of individual telecommunications networks, transmission systems, relay stations, tributary stations, and terminal equipment usually capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152, 41786, 1702294, 26893458, 8286675 ], "anchor_spans": [ [ 107, 119 ], [ 169, 187 ], [ 207, 222 ], [ 227, 241 ], [ 306, 312 ] ] }, { "plaintext": "Telecommunications is a method of communication (e.g., for sports broadcasting, mass media, journalism, etc.). Communication is the act of conveying intended meanings from one entity or group to another through the use of mutually understood signs and semiotic rules.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 113604, 19641, 15928, 29301 ], "anchor_spans": [ [ 0, 17 ], [ 66, 78 ], [ 80, 90 ], [ 92, 102 ], [ 252, 260 ] ] }, { "plaintext": "An optical communication system is any form of telecommunication that uses light as the transmission medium. Equipment consists of a transmitter, which encodes a message into an optical signal, a communication channel, which carries the signal to its destination, and a receiver, which reproduces the message from the received optical signal. Fiber-optic communication systems transmit information from one place to another by sending light through an optical fiber. The light forms a carrier signal that is modulated to carry information.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 164174, 33094374, 17939, 275871, 156700, 7309377, 17939, 3372377, 153217, 20637 ], "anchor_spans": [ [ 3, 24 ], [ 47, 64 ], [ 75, 80 ], [ 186, 192 ], [ 196, 217 ], [ 343, 368 ], [ 435, 440 ], [ 452, 465 ], [ 485, 499 ], [ 508, 517 ] ] }, { "plaintext": "A radio communication system is composed of several communications subsystems that give exterior communications capabilities. A radio communication system comprises a transmitting conductor in which electrical oscillations or currents are produced and which is arranged to cause such currents or oscillations to be propagated through the free space medium from one point to another remote therefrom and a receiving conductor at such distant point adapted to be excited by the oscillations or currents propagated from the transmitter.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 15368428, 8286675, 32502 ], "anchor_spans": [ [ 2, 28 ], [ 67, 76 ], [ 339, 349 ] ] }, { "plaintext": "Power line communication systems operate by impressing a modulated carrier signal on power wires. Different types of powerline communications use different frequency bands, depending on the signal transmission characteristics of the power wiring used. Since the power wiring system was originally intended for transmission of AC power, the power wire circuits have only a limited ability to carry higher frequencies. The propagation problem is a limiting factor for each type of power line communications.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 238420, 1780823 ], "anchor_spans": [ [ 0, 24 ], [ 326, 334 ] ] }, { "plaintext": "A duplex communication system is a system composed of two connected parties or devices which can communicate with one another in both directions. The term duplex is used when describing communication between two parties or devices. Duplex systems are employed in nearly all communications networks, either to allow for a communication \"two-way street\" between two connected parties or to provide a \"reverse path\" for the monitoring and remote adjustment of equipment in the field. An Antenna is basically a small length of a qwert conductor that is used to radiate or receive electromagnetic waves. It acts as a conversion device. At the transmitting end it converts high frequency current into electromagnetic waves. At the receiving end it transforms electromagnetic waves into electrical signals that is fed into the input of the receiver. several types of antenna are used in communication.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 2112491, 187317, 9426 ], "anchor_spans": [ [ 2, 29 ], [ 484, 491 ], [ 753, 774 ] ] }, { "plaintext": "Examples of communications subsystems include the Defense Communications System (DCS).", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 52555 ], "anchor_spans": [ [ 50, 79 ] ] }, { "plaintext": "Telephone", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 30003 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Mobile phone", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 19644137 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Tablet computer", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 4182449 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Television", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 29831 ], "anchor_spans": [ [ 0, 10 ] ] }, { "plaintext": "Telegraph", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 30010 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Edison Telegraph", "section_idx": 1, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "TV cable", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 21393793 ], "anchor_spans": [ [ 0, 8 ] ] }, { "plaintext": "Computer", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 7878457 ], "anchor_spans": [ [ 0, 8 ] ] }, { "plaintext": "A tactical communications system is a communications system that ", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 41776 ], "anchor_spans": [ [ 2, 32 ] ] }, { "plaintext": "(a) is used within, or in direct support of tactical forces", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 60981 ], "anchor_spans": [ [ 44, 58 ] ] }, { "plaintext": "(b) is designed to meet the requirements of changing tactical situations and varying environmental conditions, ", "section_idx": 1, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "(c) provides securable communications, such as voice, data, and video, among mobile users to facilitate command and control within, and in support of, tactical forces, and ", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 18985040, 32441, 7092305 ], "anchor_spans": [ [ 54, 58 ], [ 64, 69 ], [ 104, 123 ] ] }, { "plaintext": "(d) usually requires extremely short installation times, usually on the order of hours, in order to meet the requirements of frequent relocation.", "section_idx": 1, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An Emergency communication system is any system (typically computer based) that is organized for the primary purpose of supporting the two way communication of emergency messages between both individuals and groups of individuals. These systems are commonly designed to integrate the cross-communication of messages between are variety of communication technologies.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 35486581 ], "anchor_spans": [ [ 3, 33 ] ] }, { "plaintext": "An Automatic call distributor (ACD) is a communication system that automatically queues, assigns and connects callers to handlers. This is used often in customer service (such as for product or service complaints), ordering by telephone (such as in a ticket office), or coordination services (such as in air traffic control).", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 40749, 48563 ], "anchor_spans": [ [ 3, 29 ], [ 304, 323 ] ] }, { "plaintext": "A Voice Communication Control System (VCCS) is essentially an ACD with characteristics that make it more adapted to use in critical situations (no waiting for dial tone, or lengthy recorded announcements, radio and telephone lines equally easily connected to, individual lines immediately accessible etc..)", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 162228 ], "anchor_spans": [ [ 159, 168 ] ] }, { "plaintext": "Sources can be classified as electric or non-electric; they are the origins of a message or input signal. Examples of sources include but are not limited to the following:", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Audio files (MP3, WAV, etc...)", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 2316 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Graphic Image Files (GIFs)", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 12702 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Email Messages", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 9738 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Human voice", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 38481 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Television Picture", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 6014 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Electromagnetic radiation", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 9426 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": "Sensors, like microphones and cameras, capture non-electric sources, like sound and light (respectively), and convert them into electrical signals. These types of sensors are called input transducers in modern analog and digital communication systems. Without input transducers there would not be an effective way to transport non-electric sources or signals over great distances, i.e. humans would have to rely solely on our eyes and ears to see and hear things despite the distances.", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Other examples of input transducers include:", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Microphones", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 65886 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Cameras", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 52648 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " Keyboards", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 18842281 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Mouse", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 7056 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " Force sensors", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Accelerometers", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 324949 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": "Once the source signal has been converted into an electric signal, the transmitter will modify this signal for efficient transmission. In order to do this, the signal must pass through an electronic circuit containing the following components:", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Noise filter", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 476836 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Analog-to-digital converter", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 40367 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Encoder", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Modulator", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 20637 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Signal amplifier", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 9931 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": "After the signal has been amplified, it is ready for transmission. At the end of the circuit is an antenna, the point at which the signal is released as electromagnetic waves (or electromagnetic radiation).", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A communication channel is simply referring to the medium by which a signal travels. There are two types of media by which electrical signals travel, i.e. guided and unguided. Guided media refers to any medium that can be directed from transmitter to receiver by means of connecting cables. In optical fiber communication, the medium is an optical (glass-like) fiber. Other guided media might include coaxial cables, telephone wire, twisted-pairs, etc... The other type of media, unguided media, refers to any communication channel that creates space between the transmitter and receiver. For radio or RF communication, the medium is air. Air is the only thing between the transmitter and receiver for RF communication while in other cases, like sonar, the medium is usually water because sound waves travel efficiently through certain liquid media. Both types of media are considered unguided because there are no connecting cables between the transmitter and receiver. Communication channels include almost everything from the vacuum of space to solid pieces of metal; however, some mediums are preferred more than others. That is because differing sources travel through subjective mediums with fluctuating efficiencies.", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Once the signal has passed through the communication channel, it must be effectively captured by a receiver. The goal of the receiver is to capture and reconstruct the signal before it passed through the transmitter (i.e. the A/D converter, modulator and encoder). This is done by passing the \"received\" signal through another circuit containing the following components:", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Noise Filter", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Digital-to-analog converter", "section_idx": 2, "section_name": "Key components", "target_page_ids": [ 92943 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Decoder", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Demodulator", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Signal Amplifier", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Most likely the signal will have lost some of its energy after having passed through the communication channel or medium. The signal can be boosted by passing it through a signal amplifier. When the analog signal converted into digital signal.", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The output transducer simply converts the electric signal (created by the input transducer) back into its original form. Examples of output transducers include but are not limited to the following:", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Speakers (Audio)", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Monitors (See Computer Peripherals)", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Motors (Movement)", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Lighting (Visual)", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Some common pairs of input and output transducers include:", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Microphones and speakers (audio signals)", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Keyboards and computer monitors", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Cameras and liquid crystal displays (LCDs)", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Force sensors (buttons) and lights or motors", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Again, input transducers convert non-electric signals like voice into electric signals that can be transmitted over great distances very quickly. Output transducers convert the electric signal back into sound or picture, etc... There are many different types of transducers and the combinations are limitless.", "section_idx": 2, "section_name": "Key components", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Automatic call distributor", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 40749 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": " Hansell, Clarence W., , \"Communication system by pulses through the Earth\".", "section_idx": 4, "section_name": "References", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telecommunications_systems", "Telecommunications", "Military_communications", "Technology_systems" ]

[]

[ { "plaintext": "In telecommunication and signal processing, companding (occasionally called compansion) is a method of mitigating the detrimental effects of a channel with limited dynamic range. The name is a portmanteau of the words compressing and expanding, which are the functions of a compander at the transmitting and receiving end respectively. The use of companding allows signals with a large dynamic range to be transmitted over facilities that have a smaller dynamic range capability. Companding is employed in telephony and other audio applications such as professional wireless microphones and analog recording.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 29324, 41079, 16823212, 262733, 41831, 4578451, 190003 ], "anchor_spans": [ [ 3, 20 ], [ 25, 42 ], [ 164, 177 ], [ 193, 204 ], [ 218, 229 ], [ 506, 515 ], [ 566, 585 ], [ 591, 607 ] ] }, { "plaintext": "The dynamic range of a signal is compressed before transmission and is expanded to the original value at the receiver. The electronic circuit that does this is called a compander and works by compressing or expanding the dynamic range of an analog electronic signal such as sound recorded by a microphone. One variety is a triplet of amplifiers: a logarithmic amplifier, followed by a variable-gain linear amplifier and an exponential amplifier. Such a triplet has the property that its output voltage is proportional to the input voltage raised to an adjustable power.", "section_idx": 1, "section_name": "How it works", "target_page_ids": [ 609152, 41079 ], "anchor_spans": [ [ 51, 63 ], [ 221, 234 ] ] }, { "plaintext": "Companded quantization is the combination of three functional building blocks – namely, a (continuous-domain) signal dynamic range compressor, a limited-range uniform quantizer, and a (continuous-domain) signal dynamic range expander that inverts the compressor function. This type of quantization is frequently used in telephony systems. ", "section_idx": 1, "section_name": "How it works", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In practice, companders are designed to operate according to relatively simple dynamic range compressor functions that are designed to be suitable for implementation using simple analog electronic circuits. The two most popular compander functions used for telecommunications are the A-law and μ-law functions.", "section_idx": 1, "section_name": "How it works", "target_page_ids": [ 40707, 41382 ], "anchor_spans": [ [ 284, 289 ], [ 294, 299 ] ] }, { "plaintext": "Companding is used in digital telephony systems, compressing before input to an analog-to-digital converter, and then expanding after a digital-to-analog converter. This is equivalent to using a non-linear ADC as in a T-carrier telephone system that implements A-law or μ-law companding. This method is also used in digital file formats for better signal-to-noise ratio (SNR) at lower bit depths. For example, a linearly encoded 16-bit PCM signal can be converted to an 8-bit WAV or AU file while maintaining a decent SNR by compressing before the transition to 8-bit and expanding after conversion back to 16-bit. This is effectively a form of lossy audio data compression.", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 40367, 92943, 41779, 40707, 41382, 41706, 25513330, 34062, 2732, 8013 ], "anchor_spans": [ [ 80, 107 ], [ 136, 163 ], [ 219, 228 ], [ 262, 267 ], [ 271, 276 ], [ 350, 371 ], [ 439, 442 ], [ 479, 482 ], [ 486, 488 ], [ 655, 677 ] ] }, { "plaintext": "Professional wireless microphones do this since the dynamic range of the microphone audio signal itself is larger than the dynamic range provided by radio transmission. Companding also reduces the noise and crosstalk levels at the receiver.", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 4578451 ], "anchor_spans": [ [ 13, 32 ] ] }, { "plaintext": "Companders are used in concert audio systems and in some noise reduction schemes.", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 476836 ], "anchor_spans": [ [ 57, 79 ] ] }, { "plaintext": "The use of companding in an analog picture transmission system was patented by A. B. Clark of AT&T in 1928 (filed in 1925):", "section_idx": 3, "section_name": "History", "target_page_ids": [ 24536639 ], "anchor_spans": [ [ 94, 98 ] ] }, { "plaintext": "In 1942, Clark and his team completed the SIGSALY secure voice transmission system that included the first use of companding in a PCM (digital) system.", "section_idx": 3, "section_name": "History", "target_page_ids": [ 740918 ], "anchor_spans": [ [ 42, 49 ] ] }, { "plaintext": "In 1953, B. Smith showed that a nonlinear DAC could be complemented by the inverse nonlinearity in a successive-approximation ADC configuration, simplifying the design of digital companding systems.", "section_idx": 3, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In 1970, H. Kaneko developed the uniform description of segment (piecewise linear) companding laws that had by then been adopted in digital telephony.", "section_idx": 3, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the 1980s (and '90s), many of the music equipment manufacturers (Roland, Yamaha, Korg) used companding when compressing the library waveform data in their digital synthesizers. Unfortunately exact algorithms are not known, neither if any of the manufacturers ever used the Companding scheme which is described in this article. The only known thing is that manufacturers did use data compression in the mentioned time period and that some people refer to it as \"companding\" while in reality it might mean something else, for example data compression and expansion. This dates back to the late '80s when memory chips were often one of the most costly components in the instrument. Manufacturers usually quoted the amount of memory in its compressed form: i.e. 24 MB of physical waveform ROM in a Korg Trinity is actually 48 MB when uncompressed. Similarly, Roland SR-JV expansion boards were usually advertised as 8 MB boards with '16 MB-equivalent content'. Careless copying of this technical information, omitting the \"equivalence\" reference, can often cause confusion.", "section_idx": 3, "section_name": "History", "target_page_ids": [ 26531, 308428, 303444, 8247, 3076054 ], "anchor_spans": [ [ 68, 74 ], [ 76, 82 ], [ 84, 88 ], [ 158, 178 ], [ 798, 810 ] ] }, { "plaintext": " Companding: Logarithmic Laws, Implementation, and Consequences", "section_idx": 5, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Lossy_compression_algorithms", "Audio_engineering", "Sound_recording_technology" ]

[]

[ { "plaintext": "In telecommunication, a comparably efficient interconnection (CEI) is an equal-access concept developed by the FCC stating that, \". . . if a carrier offers an enhanced service, it should be required to offer network interconnection (or colocation) opportunities to others that are comparably efficient to the interconnection that its enhanced service enjoys. Accordingly, a carrier would be required to implement CEI only as it introduces new enhanced services.\" [FCC Report and Order June 16, 1986]", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 9700175, 55974, 40910, 41112, 46545, 1702294, 6262995 ], "anchor_spans": [ [ 3, 20 ], [ 73, 85 ], [ 111, 114 ], [ 141, 148 ], [ 159, 175 ], [ 208, 215 ], [ 216, 231 ], [ 236, 246 ] ] } ]

[ "Telecommunications_law", "Federal_Communications_Commission" ]

[]

[ { "plaintext": "In electronics, a comparator is a device that compares two voltages or currents and outputs a digital signal indicating which is larger. It has two analog input terminals and and one binary digital output . The output is ideally", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9663, 32549, 6207 ], "anchor_spans": [ [ 3, 14 ], [ 59, 66 ], [ 71, 79 ] ] }, { "plaintext": "A comparator consists of a specialized high-gain differential amplifier. They are commonly used in devices that measure and digitize analog signals, such as analog-to-digital converters (ADCs), as well as relaxation oscillators.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41968, 326647, 40367, 195967 ], "anchor_spans": [ [ 44, 48 ], [ 49, 71 ], [ 157, 184 ], [ 205, 226 ] ] }, { "plaintext": "The differential voltages must stay within the limits specified by the manufacturer. Early integrated comparators, like the LM111 family, and certain high-speed comparators like the LM119 family, require differential voltage ranges substantially lower than the power-supply voltages (±15V vs. 36V). Rail-to-rail comparators allow any differential voltages within the power-supply range. When powered from a bipolar (dual rail) supply, ", "section_idx": 1, "section_name": "Differential voltage", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "or when powered from an unipolar TTL/CMOS power supply,", "section_idx": 1, "section_name": "Differential voltage", "target_page_ids": [ 47769, 49420 ], "anchor_spans": [ [ 33, 36 ], [ 37, 41 ] ] }, { "plaintext": " .", "section_idx": 1, "section_name": "Differential voltage", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Specific rail-to-rail comparators with p–n–p input transistors, like the LM139 family, allow the input potential to drop 0.3volts below the negative supply rail, but do not allow it to rise above the positive rail. Specific ultra-fast comparators, like the LMH7322, allow the input signal to swing below the negative rail and above the positive rail, although by a narrow margin of only 0.2V. Differential input voltage (the voltage between two inputs) of a modern rail-to-rail comparator is usually limited only by the full swing of power supply.", "section_idx": 1, "section_name": "Differential voltage", "target_page_ids": [ 49338 ], "anchor_spans": [ [ 39, 44 ] ] }, { "plaintext": "An operational amplifier (op-amp) has a well balanced difference input and a very high gain. This parallels the characteristics of comparators and can be substituted in applications with low-performance requirements.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [ 22804, 41968 ], "anchor_spans": [ [ 3, 24 ], [ 87, 91 ] ] }, { "plaintext": "A comparator circuit compares two voltages and outputs either a 1 (the voltage at the plus side) or a 0 (the voltage at the negative side) to indicate which is larger. Comparators are often used, for example, to check whether an input has reached some predetermined value. In most cases a comparator is implemented using a dedicated comparator IC, but op-amps may be used as an alternative. Comparator diagrams and op-amp diagrams use the same symbols.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Figure 1 above shows a comparator circuit. Note first that the circuit does not use feedback. The circuit amplifies the voltage difference between Vin and VREF, and it outputs the result at Vout. If Vin is greater than VREF, then voltage at Vout will rise to its positive saturation level; that is, to the voltage at the positive side. If Vin is lower than VREF, then Vout will fall to its negative saturation level, equal to the voltage at the negative side.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In practice, this circuit can be improved by incorporating a hysteresis voltage range to reduce its sensitivity to noise. The circuit shown in Figure 1, for example, will provide stable operation even when the Vin signal is somewhat noisy.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This is because of the difference in characteristics of an operational amplifier and comparator, using an operational amplifier as a comparator presents several disadvantages as compared to using a dedicated comparator.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [ 22804 ], "anchor_spans": [ [ 106, 127 ] ] }, { "plaintext": " Op-amps are designed to operate in the linear mode with negative feedback. Hence, an op-amp typically has a lengthy recovery time from saturation. Almost all op-amps have an internal compensation capacitor which imposes slew rate limitations for high frequency signals. Consequently, an op-amp makes a sloppy comparator with propagation delays that can be as long as tens of microseconds.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [ 544672, 1275395 ], "anchor_spans": [ [ 221, 230 ], [ 326, 343 ] ] }, { "plaintext": " Since op-amps do not have any internal hysteresis, an external hysteresis network is always necessary for slow moving input signals.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The quiescent current specification of an op-amp is valid only when the feedback is active. Some op-amps show an increased quiescent current when the inputs are not equal.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A comparator is designed to produce well-limited output voltages that easily interface with digital logic. Compatibility with digital logic must be verified while using an op-amp as a comparator.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Some multiple-section op-amps may exhibit extreme channel-channel interaction when used as comparators.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Many op-amps have back to back diodes between their inputs. Op-amp inputs usually follow each other so this is fine. But comparator inputs are not usually the same. The diodes can cause unexpected current through inputs.", "section_idx": 2, "section_name": "Op-amp voltage comparator", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A comparator consists of a high gain differential amplifier whose output is compatible with the logic gates used in the digital circuit. The gain is high enough that a very small difference between the input voltages will saturate the output, the output voltage will be in either the low logic voltage band or the high logic voltage band of the gate input. Analogue op amps have been used as comparators, however a dedicated comparator chip will generally be faster than a general-purpose operational amplifier used as a comparator, and may also contain additional features such as an accurate, internal reference voltage, adjustable hysteresis, and a clock gated input.", "section_idx": 3, "section_name": "Design", "target_page_ids": [ 41968, 326647, 18168, 22804, 147003 ], "anchor_spans": [ [ 27, 36 ], [ 37, 59 ], [ 96, 106 ], [ 368, 374 ], [ 636, 646 ] ] }, { "plaintext": "A dedicated voltage comparator chip such as LM339 is designed to interface with a digital logic interface (to a TTL or a CMOS). The output is a binary state often used to interface real world signals to digital circuitry (see analog-to-digital converter). If there is a fixed voltage source from, for example, a DC adjustable device in the signal path, a comparator is just the equivalent of a cascade of amplifiers. When the voltages are nearly equal, the output voltage will not fall into one of the logic levels, thus analog signals will enter the digital domain with unpredictable results. To make this range as small as possible, the amplifier cascade is high gain. The circuit consists of mainly bipolar transistors. For very high frequencies, the input impedance of the stages is low. This reduces the saturation of the slow, large p–n junction bipolar transistors that would otherwise lead to long recovery times. Fast small Schottky diodes, like those found in binary logic designs, improve the performance significantly though the performance still lags that of circuits with amplifiers using analog signals. Slew rate has no meaning for these devices. For applications in flash ADCs the distributed signal across eight ports matches the voltage and current gain after each amplifier, and resistors then behave as level-shifters.", "section_idx": 3, "section_name": "Design", "target_page_ids": [ 47769, 49420, 40367, 49338, 41957, 571755, 227130, 4894414 ], "anchor_spans": [ [ 112, 115 ], [ 121, 125 ], [ 226, 253 ], [ 702, 720 ], [ 760, 769 ], [ 839, 851 ], [ 933, 947 ], [ 1183, 1192 ] ] }, { "plaintext": "The LM339 accomplishes this with an open collector output. When the inverting input is at a higher voltage than the non inverting input, the output of the comparator connects to the negative power supply. When the non inverting input is higher than the inverting input, the output is 'floating' (has a very high impedance to ground). The gain of op amp as comparator is given by this equation V(out)=V(in)", "section_idx": 3, "section_name": "Design", "target_page_ids": [ 4226040 ], "anchor_spans": [ [ 36, 50 ] ] }, { "plaintext": "While it is easy to understand the basic task of a comparator, that is, comparing two voltages or currents, several parameters must be considered while selecting a suitable comparator:", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "While in general comparators are \"fast,\" their circuits are not immune to the classic speed-power tradeoff. High speed comparators use transistors with larger aspect ratios and hence also consume more power. Depending on the application, select either a comparator with high speed or one that saves power. For example, nano-powered comparators in space-saving chip-scale packages (UCSP), DFN or SC70 packages such as MAX9027, LTC1540, LPV7215, MAX9060 and MCP6541 are ideal for ultra-low-power, portable applications. Likewise if a comparator is needed to implement a relaxation oscillator circuit to create a high speed clock signal then comparators having few nano seconds of propagation delay may be suitable. ADCMP572 (CML output), LMH7220 (LVDS Output), MAX999 (CMOS output / TTL output), LT1719 (CMOS output / TTL output), MAX9010 (TTL output), and MAX9601 (PECL output) are examples of some good high speed comparators.", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A comparator normally changes its output state when the voltage between its inputs crosses through approximately zero volts. Small voltage fluctuations due to noise, always present on the inputs, can cause undesirable rapid changes between the two output states when the input voltage difference is near zero volts. To prevent this output oscillation, a small hysteresis of a few millivolts is integrated into many modern comparators. ", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [ 147003 ], "anchor_spans": [ [ 360, 370 ] ] }, { "plaintext": "For example, the LTC6702, MAX9021 and MAX9031 have internal hysteresis desensitizing them from input noise. In place of one switching point, hysteresis introduces two: one for rising voltages, and one for falling voltages. The difference between the higher-level trip value (VTRIP+) and the lower-level trip value (VTRIP-) equals the hysteresis voltage (VHYST).", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "If the comparator does not have internal hysteresis or if the input noise is greater than the internal hysteresis then an external hysteresis network can be built using positive feedback from the output to the non-inverting input of the comparator. The resulting Schmitt trigger circuit gives additional noise immunity and a cleaner output signal. Some comparators such as LMP7300, LTC1540, MAX931, MAX971 and ADCMP341 also provide the hysteresis control through a separate hysteresis pin. These comparators make it possible to add a programmable hysteresis without feedback or complicated equations. Using a dedicated hysteresis pin is also convenient if the source impedance is high since the inputs are isolated from the hysteresis network. When hysteresis is added then a comparator cannot resolve signals within the hysteresis band.", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [ 379241 ], "anchor_spans": [ [ 263, 278 ] ] }, { "plaintext": "Because comparators have only two output states, their outputs are either near zero or near the supply voltage. Bipolar rail-to-rail comparators have a common-emitter output that produces a small voltage drop between the output and each rail. That drop is equal to the collector-to-emitter voltage of a saturated transistor. When output currents are light, output voltages of CMOS rail-to-rail comparators, which rely on a saturated MOSFET, range closer to the rail voltages than their bipolar counterparts.", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "On the basis of outputs, comparators can also be classified as open-drain or push–pull. Comparators with an open-drain output stage use an external pull-up resistor to a positive supply that defines the logic high level. Open-drain comparators are more suitable for mixed-voltage system design. Since the output has high impedance for logic high level, open-drain comparators can also be used to connect multiple comparators to a single bus. Push–pull output does not need a pull-up resistor and can also source current, unlike an open-drain output.", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [ 4226040, 856798, 1629621 ], "anchor_spans": [ [ 63, 73 ], [ 77, 86 ], [ 148, 164 ] ] }, { "plaintext": "The most frequent application for comparators is the comparison between a voltage and a stable reference. ", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "TL431 is widely used for this purpose.", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [ 64460834 ], "anchor_spans": [ [ 0, 5 ] ] }, { "plaintext": "Most comparator manufacturers also offer comparators in which a reference voltage is integrated on to the chip. Combining the reference and comparator in one chip not only saves space, but also draws less supply current than a comparator with an external reference. ICs with wide range of references are available such as MAX9062 (200 mV reference), LT6700 (400 mV reference), ADCMP350 (600mV reference), MAX9025 (1.236V reference), MAX9040 (2.048V reference), TLV3012 (1.24V reference) and TSM109 (2.5V reference).", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A continuous comparator will output either a \"1\" or a \"0\" any time a high or low signal is applied to its input and will change quickly when the inputs are updated. However, many applications only require comparator outputs at certain instances, such as in A/D converters and memory. By only strobing a comparator at certain intervals, higher accuracy and lower power can be achieved with a clocked (or dynamic) comparator structure, also called a latched comparator. Often latched comparators employ strong positive feedback for a \"regeneration phase\" when a clock is high, and have a \"reset phase\" when the clock is low. ", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This is in contrast to a continuous comparator, which can only employ weak positive feedback since there is no reset period.", "section_idx": 4, "section_name": "Key specifications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A null detector identifies when a given value is zero. Comparators are ideal for null detection comparison measurements, since they are equivalent to a very high gain amplifier with well-balanced inputs and controlled output limits. The null detector circuit compares two input voltages: an unknown voltage and a reference voltage, usually referred to as vu and vr. The reference voltage is usually on the non-inverting input (+), while the unknown voltage is usually on the inverting input (). (A circuit diagram would display the inputs according to their sign with respect to the output when a particular input is greater than the other.) Unless the inputs are nearly equal (see below), the output is either positive or negative, for example ±12V. In the case of a null detector the aim is to detect when the input voltages are nearly equal, which gives the value of the unknown voltage since the reference voltage is known.", "section_idx": 5, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "When using a comparator as a null detector, accuracy is limited; an output of zero is given whenever the magnitude of the voltage difference multiplied by the gain of the amplifier is within the voltage limits. For example, if the gain is 106, and the voltage limits are ±6V, then an output of zero will be given if the voltage difference is less than 6μV. One could refer to this as a fundamental uncertainty in the measurement.", "section_idx": 5, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For this type of detector, a comparator detects each time an ac pulse changes polarity. The output of the comparator changes state each time the pulse changes its polarity, that is the output is HI (high) for a positive pulse and LO (low) for a negative pulse squares the input signal.", "section_idx": 5, "section_name": "Applications", "target_page_ids": [ 42986 ], "anchor_spans": [ [ 61, 63 ] ] }, { "plaintext": "A comparator can be used to build a relaxation oscillator. It uses both positive and negative feedback. The positive feedback is a Schmitt trigger configuration. Alone, the trigger is a bistable multivibrator. However, the slow negative feedback added to the trigger by the RC circuit causes the circuit to oscillate automatically. That is, the addition of the RC circuit turns the hysteretic bistable multivibrator into an astable multivibrator.", "section_idx": 5, "section_name": "Applications", "target_page_ids": [ 195967, 379241, 21008, 213328, 21008, 21008 ], "anchor_spans": [ [ 36, 57 ], [ 131, 146 ], [ 186, 208 ], [ 228, 245 ], [ 402, 415 ], [ 424, 445 ] ] }, { "plaintext": "This circuit requires only a single comparator with an open-drain output as in the LM393, TLV3011 or MAX9028. The circuit provides great flexibility in choosing the voltages to be translated by using a suitable pull up voltage. It also allows the translation of bipolar ±5V logic to unipolar 3V logic by using a comparator like the MAX972.", "section_idx": 5, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "When a comparator performs the function of telling if an input voltage is above or below a given threshold, it is essentially performing a 1-bit quantization. This function is used in nearly all analog to digital converters (such as flash, pipeline, successive approximation, delta-sigma modulation, folding, interpolating, dual-slope and others) in combination with other devices to achieve a multi-bit quantization.", "section_idx": 5, "section_name": "Applications", "target_page_ids": [ 317018, 4894414, 5655191, 1745452, 22269055 ], "anchor_spans": [ [ 145, 157 ], [ 233, 238 ], [ 250, 274 ], [ 276, 298 ], [ 324, 334 ] ] }, { "plaintext": "Comparators can also be used as window detectors. In a window detector, a comparator is used to compare two voltages and determine whether a given input voltage is under voltage or over voltage.", "section_idx": 5, "section_name": "Applications", "target_page_ids": [ 30156816 ], "anchor_spans": [ [ 55, 70 ] ] }, { "plaintext": "Comparators can be used to create absolute-value detectors. In an absolute-value detector, two comparators and a digital logic gate are used to compare the absolute values of two voltages.", "section_idx": 5, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Constant fraction discriminator", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 3841160 ], "anchor_spans": [ [ 1, 32 ] ] }, { "plaintext": " Digital comparator", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 4533948 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Flash ADC", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 4894414 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Sorting network", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 562061 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Zero crossing threshold detector", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 42327977 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " IC Comparator reference page at http://circuitous.ca", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A Java based resistor value search tool for analysing an inverting comparator circuit with hysteresis", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Electronic_circuits", "Comparison_(mathematical)" ]

[]

[ { "plaintext": "Compatibility may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Backward compatibility, in which newer devices can understand data generated by older devices", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 4459 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Compatibility card, an expansion card for hardware emulation of another device", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 18934063 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Compatibility layer, components that allow for non-native support of components", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 540289 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Compatibility mode, software mechanism in which a software emulates an older version of software", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 33727223 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Computer compatibility, of a line of machines", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 12075392 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " IBM PC compatible, computers that are generally similar to the original IBM PC, XT, or AT", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 49803 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Hardware compatibility, between different pieces of computer hardware", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 12075392 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " License compatibility, of software licenses", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 12741271 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Pin compatibility, in devices that have the same functions assigned to the same particular pins", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 385509 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Software compatibility, between different pieces of software", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 12075392 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Software incompatibility", "section_idx": 1, "section_name": "Computing", "target_page_ids": [ 14743352 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Compatibility (biological), a property which is assigned to splits of a given set of taxa", "section_idx": 2, "section_name": "Science and mathematics", "target_page_ids": [ 11512614 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Compatibility (chemical), how stable a substance is when mixed with another substance", "section_idx": 2, "section_name": "Science and mathematics", "target_page_ids": [ 8761205 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Compatibility (geochemistry), how readily a particular trace element substitutes for a major element within a mineral", "section_idx": 2, "section_name": "Science and mathematics", "target_page_ids": [ 5571005 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Compatibility (mechanics), the study of compatible deformations in continuum mechanics", "section_idx": 2, "section_name": "Science and mathematics", "target_page_ids": [ 25800675 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Electromagnetic compatibility, which studies the unintentional generation, propagation, and reception of electromagnetic energy", "section_idx": 2, "section_name": "Science and mathematics", "target_page_ids": [ 41093 ], "anchor_spans": [ [ 1, 30 ] ] }, { "plaintext": " Consistency, logical compatibility between two or more propositions", "section_idx": 2, "section_name": "Science and mathematics", "target_page_ids": [ 75802 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Compatible relation, a binary relation that commutes with each operation of an algebraic structure", "section_idx": 2, "section_name": "Science and mathematics", "target_page_ids": [ 48167 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Astrological compatibility, a branch of astrology that studies relationships by comparing natal horoscopes", "section_idx": 3, "section_name": "Other uses", "target_page_ids": [ 2809535 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Compatibilism, a philosophical position", "section_idx": 3, "section_name": "Other uses", "target_page_ids": [ 374063 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Interpersonal compatibility, the long-term interaction between two or more individuals in terms of the ease and comfort of communication", "section_idx": 3, "section_name": "Other uses", "target_page_ids": [ 19647869 ], "anchor_spans": [ [ 1, 28 ] ] } ]

[]

[]

[ { "plaintext": "A Compatible sideband transmission, also known as amplitude modulation equivalent (AME) or Single sideband reduced-carrier (SSB-RC), is a type of single sideband RF modulation in which the carrier is deliberately reinserted at a lower level after its normal suppression to permit reception by conventional AM receivers. The general convention is to filter the lower-sideband, and communicate using only the upper-sideband and a partial carrier. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1140, 29048, 29048, 42852, 20637, 153217 ], "anchor_spans": [ [ 50, 70 ], [ 91, 106 ], [ 146, 161 ], [ 162, 164 ], [ 165, 175 ], [ 189, 196 ] ] }, { "plaintext": "The benefits of compatible-sideband over conventional AM are increased spectral efficiency due to a reduction in bandwidth of 50% as well as a decrease in wasted power. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1652911 ], "anchor_spans": [ [ 71, 90 ] ] }, { "plaintext": "By using compatible sideband instead of AM, less RF power is required at the transmitter to transmit the same quality of signal the same distance. This results in compatible sideband being almost 100% power-efficient, where regular AM is comparably only 16% power-efficient (84% of RF power wasted). ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This modulation is currently mostly used in high frequency military communications.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 178937 ], "anchor_spans": [ [ 44, 58 ] ] } ]

[ "Radio_modulation_modes" ]

[]

[ { "plaintext": "In telecommunication, a complementary network service (CNS) is a means for an enhanced-service provider customer to connect to a network and to the enhanced service provider. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 46545, 41112 ], "anchor_spans": [ [ 3, 20 ], [ 129, 136 ], [ 148, 164 ] ] }, { "plaintext": "Complementary network services usually consist of the customer local service, such as a business or residence, and several associated service features, such as a call-forwarding service.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 406703 ], "anchor_spans": [ [ 162, 166 ] ] } ]

[ "Telephone_service_enhanced_features" ]

[]

[ { "plaintext": "Component may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "System components, an entity with discrete structure, such as an assembly or software module, within a system considered at a particular level of analysis", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 8286675 ], "anchor_spans": [ [ 0, 6 ] ] }, { "plaintext": "Lumped element model, a model of spatially distributed systems", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 301928 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Component video, a type of analog video information that is transmitted or stored as two or more separate signals", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 288212 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Electronic components, the constituents of electronic circuits", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 1886820 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Symmetrical components, in electrical engineering, analysis of unbalanced three-phase power systems", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 1868834 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Color model, a way of describing how colors can be represented, typically as multiple values or color components", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 1979078 ], "anchor_spans": [ [ 0, 11 ] ] }, { "plaintext": "Component (group theory), a quasi-simple subnormal sub-group", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 4939168 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Connected component (graph theory), a maximal connected subgraph", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 246223 ], "anchor_spans": [ [ 0, 34 ] ] }, { "plaintext": "Connected component (topology), a maximal connected subspace of a topological space", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 6233 ], "anchor_spans": [ [ 0, 30 ] ] }, { "plaintext": "Vector component, result of the decomposition of a vector into various directions", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 32533 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Component (UML), definition of component in the Unified Modeling Language", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 21205307 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Component-based software engineering, a field within software engineering dealing with reusable software elements", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 2816674 ], "anchor_spans": [ [ 0, 36 ] ] }, { "plaintext": "Software component, a reusable software element with a specification, used in component-based software engineering", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 2816674 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "Component (thermodynamics), a chemically independent constituent of a phase of a system", "section_idx": 1, "section_name": "In engineering, science, and technology", "target_page_ids": [ 272063 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "Component (VTA), a light-rail station in San Jose, California", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 4272419 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Part of the grammatical structure of a sentence, a concept relating to the catena", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 33891441 ], "anchor_spans": [ [ 75, 81 ] ] }, { "plaintext": "Component ingredient, in a culinary dish", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 2679622 ], "anchor_spans": [ [ 10, 20 ] ] }, { "plaintext": "Composition (disambiguation)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 156794 ], "anchor_spans": [ [ 0, 28 ] ] }, { "plaintext": "Decomposition (disambiguation)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 1227375 ], "anchor_spans": [ [ 0, 30 ] ] }, { "plaintext": "Giant component", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2379792 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Identity component", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 1088787 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "Irreducible component", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2652476 ], "anchor_spans": [ [ 0, 21 ] ] }, { "plaintext": "Spare part", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 28385525 ], "anchor_spans": [ [ 0, 10 ] ] }, { "plaintext": "Strongly connected component", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 684680 ], "anchor_spans": [ [ 0, 28 ] ] }, { "plaintext": "Tangential and normal components", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 10387769 ], "anchor_spans": [ [ 0, 32 ] ] }, { "plaintext": "Components", "section_idx": 3, "section_name": "See also", "target_page_ids": [], "anchor_spans": [] } ]

[]

[]

[ { "plaintext": "To compromise is to make a deal between different parties where each party gives up part of their demand. In arguments, compromise is a concept of finding agreement through communication, through a mutual acceptance of terms—often involving variations from an original goal or desires. Defining and finding the best possible compromise is an important problem in fields like game theory and the voting system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 4780974, 13018310, 5177, 667459, 14850094, 11924, 99860 ], "anchor_spans": [ [ 98, 104 ], [ 110, 118 ], [ 174, 187 ], [ 206, 216 ], [ 270, 274 ], [ 376, 387 ], [ 396, 402 ] ] }, { "plaintext": "Research has indicated that suboptimal compromises are often the result of negotiators failing to realize when they have interests that are completely compatible with those of the other party and settle for suboptimal agreements. Mutually better outcomes can often be found by careful investigation of both parties' interests, especially if done early in negotiations.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The compromise solution of a multicriteria decision making or multi-criteria decision analysis problem that is the closest to the ideal could be determined by the VIKOR method, which provides a maximum utility of the majority, and a minimum individual regret of the opponent.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 265752, 1050551, 37973347 ], "anchor_spans": [ [ 43, 58 ], [ 62, 94 ], [ 163, 175 ] ] }, { "plaintext": "In international politics, the compromises most often discussed are usually regarded as nefarious deals with dictators, such as Neville Chamberlain's appeasement of Adolf Hitler. Margalit calls these \"rotten compromises.\" In democratic politics, great challenges of contemporary democracy and has become more difficult in the era of the permanent campaign, as Gutmann and Thompson show. The problem of political compromise in general is an important subject in political ethics.", "section_idx": 1, "section_name": "Politics", "target_page_ids": [ 21453, 215166, 2731583, 36686915 ], "anchor_spans": [ [ 128, 147 ], [ 150, 161 ], [ 165, 177 ], [ 461, 477 ] ] }, { "plaintext": "Politicians being willing to compromise can reduce partisanship and hostility. Politics is sometimes called the \"art of compromise\". Polling by the American Survey Center indicates that Americans take a favorable view of political compromise.", "section_idx": 1, "section_name": "Politics", "target_page_ids": [ 4411276 ], "anchor_spans": [ [ 51, 63 ] ] }, { "plaintext": "In human relationships, \"compromise\" is frequently said to be an agreement with which no party is happy because the parties involved often feel that they either gave away too much or that they received too little. In the negative connotation, compromise may be referred to as capitulation, referring to a \"surrender\" of objectives, principles, or material, in the process of negotiating an agreement. Extremism is often considered as antonym to compromise, which, depending on context, may be associated with concepts of balance and tolerance.", "section_idx": 2, "section_name": "Human relationships", "target_page_ids": [ 55671, 3764656, 2214023, 428002, 147930, 2449978, 338825 ], "anchor_spans": [ [ 231, 242 ], [ 277, 289 ], [ 307, 316 ], [ 402, 411 ], [ 435, 442 ], [ 522, 529 ], [ 534, 543 ] ] }, { "plaintext": "Constitution", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 5253 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": " Connecticut Compromise (USA)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 483308 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": "Compromise of 1850 (USA)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 45976 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Compromise of 1867 (Austria-Hungary)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 387987 ], "anchor_spans": [ [ 0, 36 ] ] }, { "plaintext": "False balance", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2721694 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": " Missouri Compromise (USA)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 7743069 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": "Three-Fifths Compromise (USA)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 483263 ], "anchor_spans": [ [ 0, 29 ] ] } ]

[ "Arguments", "Game_theory" ]

[]

[ { "plaintext": "Computer conferencing may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Teleconference supported by one or more computers", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41783 ], "anchor_spans": [ [ 0, 14 ] ] }, { "plaintext": "Web conferencing", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1558384 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Data conferencing", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2750370 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Distributed computer applications:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Instant messaging", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 55951 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Online chat", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 174492 ], "anchor_spans": [ [ 0, 11 ] ] } ]

[]

[]

[ { "plaintext": "In the evolution of modern telecommunications systems there was a requirement to connect large numbers of low-speed access devices with large telephone company 'central office' switches over common paths. During the first generations of digital networks, analog signals were digitized on line cards attached to the telephone exchange switches. In an effort to reduce local loop costs, it was decided to push this conversion closer to the customer premises by deploying small conversion devices in customer neighborhoods. These devices would combine multiple digital signals on a single link to a larger telephone switch, which would provide service to the customer. These devices were initially called remote concentrators or simply remotes.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26668156, 59602, 61136 ], "anchor_spans": [ [ 315, 333 ], [ 367, 377 ], [ 702, 721 ] ] }, { "plaintext": "In fibre-optic distribution systems which offer triple-play services (voice, television, internet) the digitization has arrived at the customer premises and signals are digitized at the source and combined using customer edge routers. This traffic enters the distribution network at an Optical Network Termination and is carried to the central office using Wavelength division multiplexing and Passive optical networking.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2065003, 80464, 1738259 ], "anchor_spans": [ [ 48, 59 ], [ 357, 389 ], [ 394, 417 ] ] }, { "plaintext": "In telecommunication, the term concentrator has the following meanings:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " In data transmission, a functional unit that permits a common path to handle more data sources than there are channels currently available within the path. A concentrator usually provides communication capability between many low-speed, usually asynchronous channels and one or more high-speed, usually synchronous channels. Usually different speeds, codes, and protocols can be accommodated on the low-speed side. The low-speed channels usually operate in contention and require buffering.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42168, 9828, 40996, 28738, 13705426 ], "anchor_spans": [ [ 4, 21 ], [ 25, 40 ], [ 63, 67 ], [ 304, 315 ], [ 458, 468 ] ] }, { "plaintext": " A device that connects a number of links with only one destination, the main function of this device is to make a kind of load balancing between two or more servers connected together, data distribution is done according to the server processing rate.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A patch panel or other component in the cable plant where cable runs converge.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3072613, 1604592 ], "anchor_spans": [ [ 3, 14 ], [ 41, 52 ] ] }, { "plaintext": " ISP used concentrators to enable modem dialing; this kind of concentrator is sometimes called a modem concentrator or a remote access concentrator. The term \"access concentrator\" is also used to describe similar provider edge equipment used in computer networks that doesn't rely on modems anymore, e.g. FTTH.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 100245, 20647197, 10848810, 3492955 ], "anchor_spans": [ [ 1, 4 ], [ 34, 39 ], [ 213, 226 ], [ 305, 309 ] ] }, { "plaintext": " Ethernet hub", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1937926 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Oxygen concentrator (Medical application)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1592074 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Remote concentrator", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 61136 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Concentrating solar power (Energy application)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 17805223 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": "Концентраторы", "section_idx": 2, "section_name": "References", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telecommunications_equipment" ]

[]

[ { "plaintext": "The concentricity error of an optical fiber is the distance between the center of the two concentric circles that specify the cladding diameter and the center of the two concentric circles that specify the core diameter. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3372377, 19049087, 20565861 ], "anchor_spans": [ [ 30, 43 ], [ 90, 108 ], [ 206, 219 ] ] }, { "plaintext": "The concentricity error is used in conjunction with tolerance fields to specify or characterize optical fiber core and cladding geometry.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41118, 522062, 20565861 ], "anchor_spans": [ [ 18, 23 ], [ 52, 61 ], [ 96, 114 ] ] }, { "plaintext": "Ovality", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 41473 ], "anchor_spans": [ [ 0, 7 ] ] }, { "plaintext": "Centration (engineering)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 468893 ], "anchor_spans": [ [ 0, 24 ] ] } ]

[ "Fiber_optics" ]

[]

[ { "plaintext": "In telecommunication, the term conditioning equipment has the following meanings: ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " At junctions of circuits, equipment used to obtain desired circuit characteristics, such as matched transmission levels, matched impedances, and equalization between facilities.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 346001, 609152, 320733, 26332696 ], "anchor_spans": [ [ 61, 68 ], [ 102, 114 ], [ 123, 141 ], [ 147, 159 ] ] }, { "plaintext": " Corrective networks used to improve data transmission, such as equalization of the insertion loss-vs.-frequency characteristic and the envelope delay distortion over a desired frequency range.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42168, 41266, 41222 ], "anchor_spans": [ [ 38, 55 ], [ 85, 99 ], [ 146, 162 ] ] } ]

[ "Communication_circuits" ]

[]

[]

[]

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[ { "plaintext": "In a communications network, a conference operation is an operation that allows a call to be established among three or more stations in such a manner that each of the stations is able to communicate directly with all the other stations. In radio systems, the stations may receive simultaneously, but must transmit one at a time. The common operational modes are \"push-to-talk\" for telephone operation and \"push-to-type\" for telegraph and data transmission.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 46545, 406703, 15368428, 30003, 42168 ], "anchor_spans": [ [ 5, 27 ], [ 82, 86 ], [ 241, 246 ], [ 382, 391 ], [ 439, 456 ] ] }, { "plaintext": "Conference call", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 406758 ], "anchor_spans": [ [ 0, 15 ] ] } ]

[ "Calling_features" ]

[]

[ { "plaintext": "Configuration management (CM) is a systems engineering process for establishing and maintaining consistency of a product's performance, functional, and physical attributes with its requirements, design, and operational information throughout its life. The CM process is widely used by military engineering organizations to manage changes throughout the system lifecycle of complex systems, such as weapon systems, military vehicles, and information systems. Outside the military, the CM process is also used with IT service management as defined by ITIL, and with other domain models in the civil engineering and other industrial engineering segments such as roads, bridges, canals, dams, and buildings.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 27764, 573528, 37438, 33496, 2526804, 237495, 46305618, 2524095, 23535218, 5623 ], "anchor_spans": [ [ 35, 54 ], [ 353, 369 ], [ 373, 387 ], [ 398, 404 ], [ 414, 431 ], [ 437, 455 ], [ 549, 553 ], [ 570, 582 ], [ 619, 641 ], [ 675, 680 ] ] }, { "plaintext": "CM applied over the life cycle of a system provides visibility and control of its performance, functional, and physical attributes. CM verifies that a system performs as intended, and is identified and documented in sufficient detail to support its projected life cycle. The CM process facilitates orderly management of system information and system changes for such beneficial purposes as to revise capability; improve performance, reliability, or maintainability; extend life; reduce cost; reduce risk and liability; or correct defects. The relatively minimal cost of implementing CM is returned manyfold in cost avoidance. The lack of CM, or its ineffectual implementation, can be very expensive and sometimes can have such catastrophic consequences such as failure of equipment or loss of life.", "section_idx": 1, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "CM emphasizes the functional relation between parts, subsystems, and systems for effectively controlling system change. It helps to verify that proposed changes are systematically considered to minimize adverse effects. Changes to the system are proposed, evaluated, and implemented using a standardized, systematic approach that ensures consistency, and proposed changes are evaluated in terms of their anticipated impact on the entire system. CM verifies that changes are carried out as prescribed and that documentation of items and systems reflects their true configuration. A complete CM program includes provisions for the storing, tracking, and updating of all system information on a component, subsystem, and system basis.", "section_idx": 1, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A structured CM program ensures that documentation (e.g., requirements, design, test, and acceptance documentation) for items is accurate and consistent with the actual physical design of the item. In many cases, without CM, the documentation exists but is not consistent with the item itself. For this reason, engineers, contractors, and management are frequently forced to develop documentation reflecting the actual status of the item before they can proceed with a change. This reverse engineering process is wasteful in terms of human and other resources and can be minimized or eliminated using CM.", "section_idx": 1, "section_name": "Introduction", "target_page_ids": [ 18935488 ], "anchor_spans": [ [ 482, 501 ] ] }, { "plaintext": "Configuration Management originated in the United States Department of Defense in the 1950s as a technical management discipline for hardware material items—and it is now a standard practice in virtually every industry. The CM process became its own technical discipline sometime in the late 1960s when the DoD developed a series of military standards called the \"480 series\" (i.e., MIL-STD-480, MIL-STD-481 and MIL-STD-483) that were subsequently issued in the 1970s. In 1991, the \"480 series\" was consolidated into a single standard known as the MIL–STD–973 that was then replaced by MIL–HDBK–61 pursuant to a general DoD goal that reduced the number of military standards in favor of industry technical standards supported by standards developing organizations (SDO). This marked the beginning of what has now evolved into the most widely distributed and accepted standard on CM, ANSI–EIA–649–1998. Now widely adopted by numerous organizations and agencies, the CM discipline's concepts include systems engineering (SE), Integrated Logistics Support (ILS), Capability Maturity Model Integration (CMMI), ISO 9000, Prince2 project management method, COBIT, ITIL, product lifecycle management, and Application Lifecycle Management. Many of these functions and models have redefined CM from its traditional holistic approach to technical management. Some treat CM as being similar to a librarian activity, and break out change control or change management as a separate or stand alone discipline.", "section_idx": 2, "section_name": "History", "target_page_ids": [ 7279897, 2336660, 18934904, 541680, 46901051, 27764, 2379782, 1288948, 147042, 353674, 1639135, 46305618, 597229, 5476231 ], "anchor_spans": [ [ 43, 78 ], [ 333, 351 ], [ 696, 715 ], [ 729, 763 ], [ 883, 895 ], [ 998, 1017 ], [ 1024, 1052 ], [ 1060, 1097 ], [ 1106, 1114 ], [ 1116, 1123 ], [ 1151, 1156 ], [ 1158, 1162 ], [ 1164, 1192 ], [ 1198, 1230 ] ] }, { "plaintext": "CM is the practice of handling changes systematically so that a system maintains its integrity over time. CM implements the policies, procedures, techniques, and tools that manage, evaluate proposed changes, track the status of changes, and maintain an inventory of system and support documents as the system changes. CM programs and plans provide technical and administrative direction to the development and implementation of the procedures, functions, services, tools, processes, and resources required to successfully develop and support a complex system. During system development, CM allows program management to track requirements throughout the life-cycle through acceptance and operations and maintenance. As changes inevitably occur in the requirements and design, they must be approved and documented, creating an accurate record of the system status. Ideally the CM process is applied throughout the system lifecycle. Most professionals mix up or get confused with Asset management (AM, see also ISO/IEC 19770), where it inventories the assets on hand. The key difference between CM and AM is that the former does not manage the financial accounting aspect but on service that the system supports or in other words, that the later (AM) is trying to realize value from an IT asset.", "section_idx": 3, "section_name": "Overview", "target_page_ids": [ 8286675, 41771, 282626, 573528, 6570919, 9505522 ], "anchor_spans": [ [ 64, 70 ], [ 85, 94 ], [ 597, 615 ], [ 912, 928 ], [ 977, 993 ], [ 1008, 1021 ] ] }, { "plaintext": "The CM process for both hardware- and software-configuration items comprises five distinct disciplines as established in the MIL–HDBK–61A and in ANSI/EIA-649. These disciplines are carried out as policies and procedures for establishing baselines and for performing a standard change-management process. The IEEE 12207 process IEEE 12207.2 also has these activities and adds \"Release management and delivery\".", "section_idx": 3, "section_name": "Overview", "target_page_ids": [ 1655299, 14599027, 643926 ], "anchor_spans": [ [ 237, 246 ], [ 277, 294 ], [ 308, 318 ] ] }, { "plaintext": "The five disciplines are:", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " CM Planning and Management: a formal document and plan to guide the CM program that includes items such as:", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Personnel", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Responsibilities and resources", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Training requirements", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Administrative meeting guidelines, including a definition of procedures and tools", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Baselining processes", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration control and configuration-status accounting", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Naming conventions", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Audits and reviews", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Subcontractor/vendor CM requirements", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration Identification (CI): consists of setting and maintaining baselines, which define the system or subsystem architecture, components, and any developments at any point in time. It is the basis by which changes to any part of a system are identified, documented, and later tracked through design, development, testing, and final delivery. CI incrementally establishes and maintains the definitive current basis for Configuration Status Accounting (CSA) of a system and its configuration items (CIs) throughout their lifecycle (development, production, deployment, and operational support) until disposal.", "section_idx": 3, "section_name": "Overview", "target_page_ids": [ 1979336 ], "anchor_spans": [ [ 484, 502 ] ] }, { "plaintext": " Configuration Control: includes the evaluation of all change-requests and change-proposals, and their subsequent approval or disapproval. It covers the process of controlling modifications to the system's design, hardware, firmware, software, and documentation.", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration Status Accounting: includes the process of recording and reporting configuration item descriptions (e.g., hardware, software, firmware, etc.) and all departures from the baseline during design and production. In the event of suspected problems, the verification of baseline configuration and approved modifications can be quickly determined.", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration Verification and Audit: an independent review of hardware and software for the purpose of assessing compliance with established performance requirements, commercial and appropriate military standards, and functional, allocated, and product baselines. Configuration audits verify that the system and subsystem configuration documentation complies with the functional and physical performance characteristics before acceptance into an architectural baseline.", "section_idx": 3, "section_name": "Overview", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The software configuration management (SCM) process is looked upon by practitioners as the best solution to handling changes in software projects. It identifies the functional and physical attributes of software at various points in time, and performs systematic control of changes to the identified attributes for the purpose of maintaining software integrity and traceability throughout the software development life cycle.", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The SCM process further defines the need to trace changes, and the ability to verify that the final delivered software has all of the planned enhancements that are supposed to be included in the release. It identifies four procedures that must be defined for each software project to ensure that a sound SCM process is implemented. They are:", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration identification", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration control", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration status accounting", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration audits", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "These terms and definitions change from standard to standard, but are essentially the same.", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration identification is the process of identifying the attributes that define every aspect of a configuration item. A configuration item is a product (hardware and/or software) that has an end-user purpose. These attributes are recorded in configuration documentation and baselined. Baselining an attribute forces formal configuration change control processes to be effected in the event that these attributes are changed.", "section_idx": 4, "section_name": "Software", "target_page_ids": [ 1655299 ], "anchor_spans": [ [ 292, 302 ] ] }, { "plaintext": " Configuration change control is a set of processes and approval stages required to change a configuration item's attributes and to re-baseline them.", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration status accounting is the ability to record and report on the configuration baselines associated with each configuration item at any moment of time.", "section_idx": 4, "section_name": "Software", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration audits are broken into functional and physical configuration audits. They occur either at delivery or at the moment of effecting the change. A functional configuration audit ensures that functional and performance attributes of a configuration item are achieved, while a physical configuration audit ensures that a configuration item is installed in accordance with the requirements of its detailed design documentation.", "section_idx": 4, "section_name": "Software", "target_page_ids": [ 17440612 ], "anchor_spans": [ [ 53, 81 ] ] }, { "plaintext": "ITIL specifies the use of a Configuration management system (CMS) or Configuration management database (CMDB) as a means of achieving industry best practices for Configuration Management. CMDBs are used to track Configuration Items (CIs) and the dependencies between them, where CIs represent the things in an enterprise that are worth tracking and managing, such as but not limited to computers, software, software licenses, racks, network devices, storage, and even the components within such items.", "section_idx": 4, "section_name": "Software", "target_page_ids": [ 46305618, 3267841 ], "anchor_spans": [ [ 0, 4 ], [ 69, 102 ] ] }, { "plaintext": "The benefits of a CMS/CMDB includes being able to perform functions like root cause analysis, impact analysis, change management, and current state assessment for future state strategy development. Example systems, commonly identifies themselves as IT Service Management (ITSM) systems, include FreshService, ServiceNow and Samanage.", "section_idx": 4, "section_name": "Software", "target_page_ids": [ 1132223 ], "anchor_spans": [ [ 249, 277 ] ] }, { "plaintext": "For information assurance, CM can be defined as the management of security features and assurances through control of changes made to hardware, software, firmware, documentation, test, test fixtures, and test documentation throughout the life cycle of an information system. CM for information assurance, sometimes referred to as Secure Configuration Management, relies upon performance, functional, and physical attributes of IT platforms and products and their environments to determine the appropriate security features and assurances that are used to measure a system configuration state. For example, configuration requirements may be different for a network firewall that functions as part of an organization's Internet boundary versus one that functions as an internal local network firewall.", "section_idx": 4, "section_name": "Software", "target_page_ids": [ 6444716, 26173989 ], "anchor_spans": [ [ 4, 25 ], [ 656, 672 ] ] }, { "plaintext": "Configuration management is used to maintain an understanding of the status of complex assets with a view to maintaining the highest level of serviceability for the lowest cost. Specifically, it aims to ensure that operations are not disrupted due to the asset (or parts of the asset) overrunning limits of planned lifespan or below quality levels.", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the military, this type of activity is often classed as \"mission readiness\", and seeks to define which assets are available and for which type of mission; a classic example is whether aircraft on board an aircraft carrier are equipped with bombs for ground support or missiles for defense.", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Configuration management can be used to maintain OS configuration files. Example systems include Ansible, Bcfg2, CFEngine, Chef, Nix, Otter, Puppet, Quattor, SaltStack, Terraform, Pulumi and Vagrant. Many of these systems utilize Infrastructure as Code to define and maintain configuration.", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [ 22194, 36219037, 10803998, 1109117, 22561399, 16796173, 856954, 14432911, 1573491, 33960422, 53043861, 35819849, 49263763 ], "anchor_spans": [ [ 49, 51 ], [ 97, 104 ], [ 106, 111 ], [ 113, 121 ], [ 123, 127 ], [ 129, 132 ], [ 134, 139 ], [ 141, 147 ], [ 149, 156 ], [ 158, 167 ], [ 169, 178 ], [ 191, 198 ], [ 230, 252 ] ] }, { "plaintext": "The Promise theory of configuration maintenance was developed by Mark Burgess, with a practical implementation on present day computer systems in the software CFEngine able to perform real time repair as well as preventive maintenance.", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [ 17487236, 6372337 ], "anchor_spans": [ [ 4, 18 ], [ 65, 77 ] ] }, { "plaintext": "Understanding the \"as is\" state of an asset and its major components is an essential element in preventive maintenance as used in maintenance, repair, and overhaul and enterprise asset management systems.", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [ 2286665 ], "anchor_spans": [ [ 168, 195 ] ] }, { "plaintext": "Complex assets such as aircraft, ships, industrial machinery etc. depend on many different components being serviceable. This serviceability is often defined in terms of the amount of usage the component has had since it was new, since fitted, since repaired, the amount of use it has had over its life and several other limiting factors. Understanding how near the end of their life each of these components is has been a major undertaking involving labor-intensive record keeping until recent developments in software.", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Many types of component use electronic sensors to capture data which provides live condition monitoring. This data is analyzed on board or at a remote location by computer to evaluate its current serviceability and increasingly its likely future state using algorithms which predict potential future failures based on previous examples of failure through field experience and modeling. This is the basis for \"predictive maintenance\".", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [ 2890021 ], "anchor_spans": [ [ 83, 103 ] ] }, { "plaintext": "Availability of accurate and timely data is essential in order for CM to provide operational value and a lack of this can often be a limiting factor. Capturing and disseminating the operating data to the various support organizations is becoming an industry in itself.", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The consumers of this data have grown more numerous and complex with the growth of programs offered by original equipment manufacturers (OEMs). These are designed to offer operators guaranteed availability and make the picture more complex with the operator managing the asset but the OEM taking on the liability to ensure its serviceability.", "section_idx": 5, "section_name": "Maintenance systems", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A number of standards support or include configuration management, including:", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI/EIA-649-1998 National Consensus Standard for Configuration Management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " EIA-649-A 2004 National Consensus Standard for Configuration Management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI EIA-649-C 2019 Configuration Management Standard", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ISO 10007 Quality management systems – Guidelines for configuration management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [ 27666331 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Federal Standard 1037C", "section_idx": 6, "section_name": "Standards", "target_page_ids": [ 37310 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " GEIA Standard 836–2002 Configuration Management Data Exchange and Interoperability", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " IEEE 829 Standard for Software Test Documentation", "section_idx": 6, "section_name": "Standards", "target_page_ids": [ 1348016 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " MIL-STD-973 Configuration Management (cancelled on 20 September 2000)", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " NATO STANAG 4427 Configuration Management in Systems Life Cycle Management including", "section_idx": 6, "section_name": "Standards", "target_page_ids": [ 54288480 ], "anchor_spans": [ [ 1, 75 ] ] }, { "plaintext": " NATO ACMP 2000 Policy on Configuration Management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " NATO ACMP 2009 Guidance on Configuration Management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " NATO ACMP 2100 Configuration Management Contractual Requirements", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " CMMI CMMI for Development, Version 1.2 Configuration Management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [ 1288948 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": " CMII-100E CMII Standard for Enterprise Configuration Management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Extended List of Configuration Management & Related Standards", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ITIL Service Asset and Configuration Management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ISO 20000:1 2011& 2018 Service Management System.", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ECSS-M-ST-40C Rev.1 Configuration and information management", "section_idx": 6, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " IEEE 828-2012 Standard for Configuration Management in Systems and Software Engineering, published date:2012-03-16", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ISO 10007:2017 Quality management – Guidelines for configuration management", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " NATO ACMP-2009 – Guidance on configuration management", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI/EIA-632-1998 Processes for Engineering a System", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI/EIA-649-1998 National Consensus Standard for Configuration Management", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " GEIA-HB-649 – Implementation Guide for Configuration Management", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " EIA-836 Consensus Standard for Configuration Management Data Exchange and Interoperability", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " MIL-HDBK-61B Configuration Management Guidance, 7 April 2020", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " MIL-STD-3046 Configuration Management, 6 March 2013 and canceled on June 1, 2015", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Defense Acquisition Guidebook, elements of CM at 4.3.7 SE Processes, attributes of CM at 5.1.7 Lifecycle support", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Systems Engineering Fundamentals, Chapter 10 Configuration Management", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Configuration Management Plan United States Dept. of Defense Acquisition document", "section_idx": 7, "section_name": "Guidelines", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "More recently configuration management has been applied to large construction projects which can often be very complex and have a huge number of details and changes that need to be documented. Construction agencies such as the Federal Highway Administration have used configuration management for their infrastructure projects. There are construction-based configuration management tools that aim to document change orders and RFIs in order to ensure a project stays on schedule and on budget. These programs can also store information to aid in the maintenance and modification of the infrastructure when it is completed. One such application, ccsNet, was tested in a case study funded by the Federal Transportation Administration (FTA) in which the efficacy of configuration management was measured through comparing the approximately 80% complete construction of the Los Angeles County Metropolitan Transit Agency (LACMTA) first and second segments of the Red Line, a $5.3billion rail construction project. This study yielded results indicating a benefit to using configuration management on projects of this nature.", "section_idx": 8, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Change detection", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 10543268 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Granular Configuration Automation", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 28563687 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Comparison of open source configuration management software", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 9672896 ], "anchor_spans": [ [ 1, 60 ] ] }, { "plaintext": " Dependency", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 206457 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " List of software engineering topics", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 357616 ], "anchor_spans": [ [ 1, 36 ] ] }, { "plaintext": " Interchangeable parts", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 908518 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Continuous configuration automation", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 50512186 ], "anchor_spans": [ [ 1, 36 ] ] }, { "plaintext": " System configuration", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 12935976 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Systems management", "section_idx": 9, "section_name": "See also", "target_page_ids": [ 2726769 ], "anchor_spans": [ [ 1, 19 ] ] } ]

[ "Configuration_management", "Method_engineering", "Technical_communication", "Version_control_systems", "Computer_occupations", "Systems_engineering", "Software_engineering" ]

[ "component repository management" ]

[ { "plaintext": "Congestion may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Excessive fluid in tissues, vessels, or both, including: ", "section_idx": 1, "section_name": "Medicine", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Edema, abnormal accumulation of fluid in the interstitium, manifesting as swelling", "section_idx": 1, "section_name": "Medicine", "target_page_ids": [ 70426, 2995864 ], "anchor_spans": [ [ 1, 6 ], [ 46, 58 ] ] }, { "plaintext": " Peripheral edema, edema in peripheral body parts such as limbs and feet", "section_idx": 1, "section_name": "Medicine", "target_page_ids": [ 2197257 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Pulmonary edema, edema in the lungs that impairs breathing", "section_idx": 1, "section_name": "Medicine", "target_page_ids": [ 418160 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Congestive heart failure, heart failure resulting in congestion in one or more organs", "section_idx": 1, "section_name": "Medicine", "target_page_ids": [ 249930 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Nasal congestion, the blockage of nasal passages due to swollen membranes", "section_idx": 1, "section_name": "Medicine", "target_page_ids": [ 1738117 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Prostatic congestion, a medical condition that happens when the prostate becomes swollen by excess fluid", "section_idx": 1, "section_name": "Medicine", "target_page_ids": [ 4634935 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Network congestion, reduced quality of service when a network is carrying more data than it can handle", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 430522 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Traffic congestion, vehicles clogging streets and highways", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 234226 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Congestion pricing, a system of surcharging users of public goods that are subject to congestion through excess demand", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 229073 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Congestion (film), a 1918 silent film", "section_idx": 2, "section_name": "Other uses", "target_page_ids": [ 57839238 ], "anchor_spans": [ [ 1, 18 ] ] } ]

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[ { "plaintext": "Connectionless communication, often referred to as CL-mode communication, is a data transmission method used in packet switching networks in which each data unit is individually addressed and routed based on information carried in each unit, rather than in the setup information of a prearranged, fixed data channel as in connection-oriented communication.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152, 43339, 2137712 ], "anchor_spans": [ [ 84, 96 ], [ 112, 128 ], [ 322, 355 ] ] }, { "plaintext": "Under connectionless communication between two network end points, a message can be sent from one end point to another without prior arrangement. The device at one end of the communication transmits data addressed to the other, without first ensuring that the recipient is available and ready to receive the data. Some protocols allow for error correction by requesting retransmission. Internet Protocol (IP) and User Datagram Protocol (UDP) are connectionless protocols.", "section_idx": 1, "section_name": "Attributes", "target_page_ids": [ 15323, 31929 ], "anchor_spans": [ [ 386, 403 ], [ 413, 435 ] ] }, { "plaintext": "A packet transmitted in a connectionless mode is frequently called a datagram.", "section_idx": 1, "section_name": "Attributes", "target_page_ids": [ 40994 ], "anchor_spans": [ [ 69, 77 ] ] }, { "plaintext": "Connectionless protocols are usually described as stateless protocols because the end points have no protocol-defined way to remember where they are in a \"conversation\" of message exchanges.", "section_idx": 1, "section_name": "Attributes", "target_page_ids": [ 479753 ], "anchor_spans": [ [ 50, 68 ] ] }, { "plaintext": "Connectionless communication has lower overhead than connection-oriented communication because in connection-oriented communication the communicating peers must first establish a logical or physical data channel or connection in a dialog preceding the exchange of user data.", "section_idx": 1, "section_name": "Attributes", "target_page_ids": [ 41476, 2137712, 2137712 ], "anchor_spans": [ [ 39, 47 ], [ 53, 86 ], [ 98, 131 ] ] }, { "plaintext": "Connectionless communication allows for multicast and broadcast operations in which the same data are transmitted to several recipients in a single transmission.", "section_idx": 1, "section_name": "Attributes", "target_page_ids": [ 20407, 2704540 ], "anchor_spans": [ [ 40, 49 ], [ 54, 63 ] ] }, { "plaintext": "In connectionless transmissions the service provider usually cannot guarantee that there will be no loss, error insertion, misdelivery, duplication, or out-of-sequence delivery of the packet. However, the effect of errors may be reduced by implementing error correction within an application protocol.", "section_idx": 1, "section_name": "Attributes", "target_page_ids": [ 41118, 27838 ], "anchor_spans": [ [ 106, 111 ], [ 159, 167 ] ] }, { "plaintext": "In connectionless mode there is less opportunity for optimization possible when sending several data units between the same two peers. By establishing a connection at the beginning of such a data exchange the components (routers, bridges) along the network path would be able to pre-compute (and hence cache) routing-related information, avoiding re-computation for every packet. In connection-oriented communication, network components can also reserve capacity for the transfer of the subsequent data units of a video download, for example.", "section_idx": 1, "section_name": "Attributes", "target_page_ids": [ 25748, 2702169, 6829 ], "anchor_spans": [ [ 221, 227 ], [ 230, 237 ], [ 302, 307 ] ] }, { "plaintext": "Distinction between connectionless and connection-oriented transmission may take place at several layers of the OSI Reference Model:", "section_idx": 2, "section_name": "Architecture and implementations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Transport layer: TCP is a connection-oriented transport protocol. UDP is connectionless.", "section_idx": 2, "section_name": "Architecture and implementations", "target_page_ids": [ 146145, 30538, 146145, 31929 ], "anchor_spans": [ [ 1, 16 ], [ 18, 21 ], [ 47, 65 ], [ 67, 70 ] ] }, { "plaintext": " Network layer.", "section_idx": 2, "section_name": "Architecture and implementations", "target_page_ids": [ 85024 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Data link layer: The IEEE 802.2 protocol at the Logical Link Control sublayer of the data link layer may provide both connectionless and connection-oriented services. In fact, some network protocols (such as SNA's Path Control in its early stages) require a connection-oriented data link layer. Others (like IP) do not. (After the appearance of APPN, SNA could operate on a connectionless data link service as well.)", "section_idx": 2, "section_name": "Architecture and implementations", "target_page_ids": [ 152949, 15222, 145459, 28030850, 78267, 15323, 3908774 ], "anchor_spans": [ [ 1, 16 ], [ 22, 32 ], [ 49, 69 ], [ 182, 198 ], [ 209, 212 ], [ 309, 311 ], [ 346, 350 ] ] }, { "plaintext": "Notable connectionless protocols are: Internet Protocol (IP), User Datagram Protocol (UDP), Internet Control Message Protocol (ICMP), Internetwork Packet Exchange (IPX), Transparent Inter-process Communication, NetBIOS, and Fast and Secure Protocol (FASP).", "section_idx": 2, "section_name": "Architecture and implementations", "target_page_ids": [ 15323, 31929, 15107, 15078, 5378643, 177746, 56353049 ], "anchor_spans": [ [ 38, 55 ], [ 62, 84 ], [ 92, 125 ], [ 134, 162 ], [ 170, 209 ], [ 212, 219 ], [ 225, 249 ] ] } ]

[ "Network_protocols", "Computer_networking", "Internet_architecture", "Internet_protocols" ]

[ "Connectionless", "CL-mode" ]

[ { "plaintext": "In telecommunication, the term connections per circuit hour (CCH) has the following meanings: ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "A unit of teletraffic measurement expressed as the number of connections established at a switching point per hour.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1536216 ], "anchor_spans": [ [ 10, 21 ] ] }, { "plaintext": "A unit of traffic measurement used to express the rate at which circuits are established at a switch.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26668156 ], "anchor_spans": [ [ 94, 100 ] ] }, { "plaintext": "The magnitude of the CCH is an instantaneous value subject to change as a function of time (i.e. from moment to moment), and is subject to study including load curve and busy hour as other measures of traffic are.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 30012, 4490333, 6968491 ], "anchor_spans": [ [ 86, 90 ], [ 155, 165 ], [ 170, 179 ] ] }, { "plaintext": "Busy Hour Call Attempts", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 6968491 ], "anchor_spans": [ [ 0, 23 ] ] } ]

[ "Teletraffic" ]

[]

[ { "plaintext": "Connectivity exchange (CONEX): In an adaptive or manually operated high-frequency (HF) radio network, the automatic or manual exchange of information concerning routes to stations that are not directly reachable by the exchange originator. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 178937, 224694, 18985062 ], "anchor_spans": [ [ 68, 82 ], [ 88, 101 ], [ 139, 150 ] ] }, { "plaintext": "The purpose of the exchange is to identify indirect paths and/or possible relay stations to those stations that are not directly reachable.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26590 ], "anchor_spans": [ [ 74, 79 ] ] } ]

[ "Radio_technology" ]

[]

[ { "plaintext": "Contention may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The main contention, in rhetoric and logic, the main point being argued", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 7974249 ], "anchor_spans": [ [ 5, 20 ] ] }, { "plaintext": " Resource contention, a general concept in communications and computing, is competition by users of a system for the facility at the same time:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 13440885 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Contention (telecommunications), a channel access method", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 13705426 ], "anchor_spans": [ [ 1, 32 ] ] }, { "plaintext": " The contention ratio, in computer networking, competition that applies specifically to the number of people connected to an ISP who share a set amount of bandwidth", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 10126527 ], "anchor_spans": [ [ 5, 21 ] ] }, { "plaintext": " Lock contention, in computer science, where a mutual exclusion lock reduces the throughput by hindering the concurrency of a program", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 244593 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": "Bus contention, in computer design, where multiple devices on a computer bus attempt to use it at the same time", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 376507 ], "anchor_spans": [ [ 0, 14 ] ] }, { "plaintext": "Contentious politics", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2195817 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Contention City, Arizona, a ghost town also known as Contention", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8648172 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "FV4401 Contentious, a British cold war armoured fighting vehicle project", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 30120550 ], "anchor_spans": [ [ 0, 18 ] ] } ]

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[ { "plaintext": "In telecommunication, continuous operation is an operation in which certain components, such as nodes, facilities, circuits, or equipment, are in an operational state at all times. Continuous operation usually requires that there be fully redundant configuration, or at least a sufficient X out of Y degree of redundancy for compatible equipment, where X is the number of spare components and Y is the number of operational components. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 41132, 346001, 1953581, 28385525 ], "anchor_spans": [ [ 3, 20 ], [ 103, 113 ], [ 115, 123 ], [ 310, 320 ], [ 372, 377 ] ] } ]

[ "Telecommunications_engineering", "Reliability_engineering" ]

[]

[ { "plaintext": "Contrast may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Contrast (vision), the difference in color and light between parts of an image", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 5611461 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Contrast (statistics), a combination of averages whose coefficients add up to zero, or the difference between two means", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 5611564 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Behavioral contrast, a phenomenon studied in psychology (behavior analysis)", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 7506663 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Contrast agent, used to distinguish structures or fluids within a body, often shortened to just \"contrast\"", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 3244736 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Contrast ratio, a measure of a display system", "section_idx": 2, "section_name": "Technology", "target_page_ids": [ 797610 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Display contrast, of electronic visual displays", "section_idx": 2, "section_name": "Technology", "target_page_ids": [ 15542466 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Contrast (linguistics), expressing distinctions between words", "section_idx": 3, "section_name": "Language", "target_page_ids": [ 5611554 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Contrast (literary), describing the difference(s) between two or more entities", "section_idx": 3, "section_name": "Language", "target_page_ids": [ 659073 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " The Contrast (band), an English pop band formed in 1999", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 8263152 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Contrast (music), the difference between parts or different instrumental sounds", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 5611544 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Contrast (Conor Maynard album), 2012", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 35625576 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Contrast (Matt Fax album), 2017", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 56015219 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Contrast (EP), by the Features, 2006", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 18120594 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Contrast, by Emi Maria, 2010", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 24001888 ], "anchor_spans": [ [ 14, 23 ] ] }, { "plaintext": " Contrast, by Klinik, 1992", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 618919 ], "anchor_spans": [ [ 14, 20 ] ] }, { "plaintext": " Contrast, by Signal Aout 42, 1990", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 34268082 ], "anchor_spans": [ [ 14, 28 ] ] }, { "plaintext": " Contrast, an EP by Toru Kitajima, 2014", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 52202610 ], "anchor_spans": [ [ 20, 33 ] ] }, { "plaintext": " Contrast (video game), a 2013 puzzle-based platform game", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 39804217 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " The Contrast (play), a 1787 play by Royall Tyler", "section_idx": 4, "section_name": "Arts and entertainment", "target_page_ids": [ 8528559 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Contrastive (disambiguation)", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 33647117 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Contrasts (disambiguation)", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 13980230 ], "anchor_spans": [ [ 1, 27 ] ] } ]

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[ { "plaintext": "In telecommunication, control communications is the branch of technology devoted to the design, development, and application of communications facilities used specifically for control purposes, such as for controlling (a) industrial processes, (b) movement of resources, (c) electric power generation, distribution, and utilization, (d) communications networks, and (e) transportation systems.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 33094374, 3270043 ], "anchor_spans": [ [ 3, 20 ], [ 128, 142 ], [ 275, 289 ] ] } ]

[ "Telecommunications_engineering", "Control_engineering" ]

[]

[ { "plaintext": "In telecommunication, a controlled area is an area in which uncontrolled movement will not result in compromise of classified information, that is designed to provide administrative control and safety, or that serves as a buffer for controlling access to limited-access areas. It can also refer to an area to which security controls have been applied to protect an information-processing system's equipment and wirelines, equivalent to that required for the information transmitted through the system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 40936, 252857, 489870, 40684, 41684, 8286675 ], "anchor_spans": [ [ 3, 20 ], [ 101, 111 ], [ 115, 137 ], [ 222, 228 ], [ 233, 251 ], [ 315, 323 ], [ 388, 394 ] ] } ]

[ "Privacy_of_telecommunications" ]

[]

[ { "plaintext": "In telecommunication, a control operation (control function) is an operation that affects the recording, processing, transmission, or interpretation of data. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 47772, 609152, 18985040 ], "anchor_spans": [ [ 3, 20 ], [ 67, 76 ], [ 117, 129 ], [ 152, 156 ] ] }, { "plaintext": "Examples of control operations incswayam", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Cjjgjjiglude a font change, or a rewind; and transmitting an end-of-transmission (EOT) control character.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5298 ], "anchor_spans": [ [ 87, 104 ] ] } ]

[ "Data_transmission" ]

[]

[ { "plaintext": "In telecommunication, a convolutional code is a type of error-correcting code that generates parity symbols via the sliding application of a boolean polynomial function to a data stream. The sliding application represents the 'convolution' of the encoder over the data, which gives rise to the term 'convolutional coding'. The sliding nature of the convolutional codes facilitates trellis decoding using a time-invariant trellis. Time invariant trellis decoding allows convolutional codes to be maximum-likelihood soft-decision decoded with reasonable complexity.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 4237207, 1048680, 12575446 ], "anchor_spans": [ [ 3, 20 ], [ 56, 77 ], [ 141, 159 ], [ 383, 390 ] ] }, { "plaintext": "The ability to perform economical maximum likelihood soft decision decoding is one of the major benefits of convolutional codes. This is in contrast to classic block codes, which are generally represented by a time-variant trellis and therefore are typically hard-decision decoded. Convolutional codes are often characterized by the base code rate and the depth (or memory) of the encoder . The base code rate is typically given as , where is the raw input data rate and is the data rate of output channel encoded stream. is less than because channel coding inserts redundancy in the input bits. The memory is often called the \"constraint length\" , where the output is a function of the current input as well as the previous inputs. The depth may also be given as the number of memory elements in the polynomial or the maximum possible number of states of the encoder (typically : ).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Convolutional codes are often described as continuous. However, it may also be said that convolutional codes have arbitrary block length, rather than being continuous, since most real-world convolutional encoding is performed on blocks of data. Convolutionally encoded block codes typically employ termination. The arbitrary block length of convolutional codes can also be contrasted to classic block codes, which generally have fixed block lengths that are determined by algebraic properties.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1134659 ], "anchor_spans": [ [ 397, 407 ] ] }, { "plaintext": "The code rate of a convolutional code is commonly modified via symbol puncturing. For example, a convolutional code with a 'mother' code rate may be punctured to a higher rate of, for example, simply by not transmitting a portion of code symbols. The performance of a punctured convolutional code generally scales well with the amount of parity transmitted. The ability to perform economical soft decision decoding on convolutional codes, as well as the block length and code rate flexibility of convolutional codes, makes them very popular for digital communications.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3547060 ], "anchor_spans": [ [ 63, 80 ] ] }, { "plaintext": "Convolutional codes were introduced in 1955 by Peter Elias. It was thought that convolutional codes could be decoded with arbitrary quality at the expense of computation and delay. In 1967, Andrew Viterbi determined that convolutional codes could be maximum-likelihood decoded with reasonable complexity using time invariant trellis based decoders — the Viterbi algorithm. Other trellis-based decoder algorithms were later developed, including the BCJR decoding algorithm.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 2067112, 326326, 228015, 8846521 ], "anchor_spans": [ [ 47, 58 ], [ 192, 206 ], [ 356, 373 ], [ 451, 455 ] ] }, { "plaintext": "Recursive systematic convolutional codes were invented by Claude Berrou around 1991. These codes proved especially useful for iterative processing including the processing of concatenated codes such as turbo codes.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 517835, 497535 ], "anchor_spans": [ [ 58, 71 ], [ 203, 214 ] ] }, { "plaintext": "Using the \"convolutional\" terminology, a classic convolutional code might be considered a Finite impulse response (FIR) filter, while a recursive convolutional code might be considered an Infinite impulse response (IIR) filter.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 443101, 570140 ], "anchor_spans": [ [ 90, 113 ], [ 188, 213 ] ] }, { "plaintext": "Convolutional codes are used extensively to achieve reliable data transfer in numerous applications, such as digital video, radio, mobile communications (e.g., in GSM, GPRS, EDGE and 3G networks (until 3GPP Release 7)) and satellite communications. These codes are often implemented in concatenation with a hard-decision code, particularly Reed–Solomon. Prior to turbo codes such constructions were the most efficient, coming closest to the Shannon limit.", "section_idx": 2, "section_name": "Where convolutional codes are used", "target_page_ids": [ 8733, 1145887, 45207, 11763375, 45600, 497535, 71085 ], "anchor_spans": [ [ 109, 122 ], [ 131, 152 ], [ 223, 247 ], [ 286, 299 ], [ 340, 352 ], [ 363, 374 ], [ 441, 454 ] ] }, { "plaintext": "To convolutionally encode data, start with k memory registers, each holding one input bit. Unless otherwise specified, all memory registers start with a value of 0. The encoder has n modulo-2 adders (a modulo 2 adder can be implemented with a single Boolean XOR gate, where the logic is: , , , ), and n generator polynomials one for each adder (see figure below). An input bit m1 is fed into the leftmost register. Using the generator polynomials and the existing values in the remaining registers, the encoder outputs n symbols. These symbols may be transmitted or punctured depending on the desired code rate. Now bit shift all register values to the right (m1 moves to m0, m0 moves to m−1) and wait for the next input bit. If there are no remaining input bits, the encoder continues shifting until all registers have returned to the zero state (flush bit termination).", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [ 486432, 426856, 54476844, 3521050, 16259862, 264399 ], "anchor_spans": [ [ 45, 60 ], [ 194, 199 ], [ 252, 259 ], [ 260, 268 ], [ 305, 325 ], [ 623, 632 ] ] }, { "plaintext": "The figure below is a rate () encoder with constraint length (k) of 3. Generator polynomials are , and . Therefore, output bits are calculated (modulo 2) as follows:", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "n1 = m1 + m0 + m−1", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "n2 = m0 + m−1", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "n3 = m1 + m−1.", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Convolutional codes can be systematic and non-systematic:", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " systematic repeats the structure of the message before encoding", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " non-systematic changes the initial structure", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Non-systematic convolutional codes are more popular due to better noise immunity. It relates to the free distance of the convolutional code.", "section_idx": 3, "section_name": "Convolutional encoding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The encoder on the picture above is a non-recursive encoder. Here's an example of a recursive one and as such it admits a feedback structure:", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The example encoder is systematic because the input data is also used in the output symbols (Output 2). Codes with output symbols that do not include the input data are called non-systematic.", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [ 8722775 ], "anchor_spans": [ [ 23, 33 ] ] }, { "plaintext": "Recursive codes are typically systematic and, conversely, non-recursive codes are typically non-systematic. It isn't a strict requirement, but a common practice.", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The example encoder in Img. 2. is an 8-state encoder because the 3 registers will create 8 possible encoder states (23). A corresponding decoder trellis will typically use 8 states as well.", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Recursive systematic convolutional (RSC) codes have become more popular due to their use in Turbo Codes. Recursive systematic codes are also referred to as pseudo-systematic codes.", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Other RSC codes and example applications include:", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Useful for LDPC code implementation and as inner constituent code for serial concatenated convolutional codes (SCCC's).", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [ 516393, 42381647 ], "anchor_spans": [ [ 11, 15 ], [ 70, 109 ] ] }, { "plaintext": "Useful for SCCC's and multidimensional turbo codes.", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Useful as constituent code in low error rate turbo codes for applications such as satellite links. Also suitable as SCCC outer code.", "section_idx": 4, "section_name": "Recursive and non-recursive codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A convolutional encoder is called so because it performs a convolution of the input stream with the encoder's impulse responses:", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [ 7519 ], "anchor_spans": [ [ 59, 70 ] ] }, { "plaintext": "where is an input sequence, is a sequence from output , is an impulse response for output and denotes convolution.", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A convolutional encoder is a discrete linear time-invariant system. Every output of an encoder can be described by its own transfer function, which is closely related to the generator polynomial. An impulse response is connected with a transfer function through Z-transform.", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [ 1383899, 31146, 171589 ], "anchor_spans": [ [ 38, 66 ], [ 123, 140 ], [ 262, 273 ] ] }, { "plaintext": "Transfer functions for the first (non-recursive) encoder are:", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Transfer functions for the second (recursive) encoder are:", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Define by", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where, for any rational function ,", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [ 361210 ], "anchor_spans": [ [ 15, 32 ] ] }, { "plaintext": " .", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Then is the maximum of the polynomial degrees of the ", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [ 5930652 ], "anchor_spans": [ [ 28, 46 ] ] }, { "plaintext": ", and the constraint length is defined as . For instance, in the first example the constraint length is 3, and in the second the constraint length is 4.", "section_idx": 5, "section_name": "Impulse response, transfer function, and constraint length", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A convolutional encoder is a finite state machine. An encoder with n binary cells will have 2n states.", "section_idx": 6, "section_name": "Trellis diagram", "target_page_ids": [ 10931 ], "anchor_spans": [ [ 29, 49 ] ] }, { "plaintext": "Imagine that the encoder (shown on Img.1, above) has '1' in the left memory cell (m0), and '0' in the right one (m−1). (m1 is not really a memory cell because it represents a current value). We will designate such a state as \"10\". According to an input bit the encoder at the next turn can convert either to the \"01\" state or the \"11\" state. One can see that not all transitions are possible for (e.g., a decoder can't convert from \"10\" state to \"00\" or even stay in \"10\" state).", "section_idx": 6, "section_name": "Trellis diagram", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "All possible transitions can be shown as below:", "section_idx": 6, "section_name": "Trellis diagram", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An actual encoded sequence can be represented as a path on this graph. One valid path is shown in red as an example.", "section_idx": 6, "section_name": "Trellis diagram", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This diagram gives us an idea about decoding: if a received sequence doesn't fit this graph, then it was received with errors, and we must choose the nearest correct (fitting the graph) sequence. The real decoding algorithms exploit this idea.", "section_idx": 6, "section_name": "Trellis diagram", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The free distance (d) is the minimal Hamming distance between different encoded sequences. The correcting capability (t) of a convolutional code is the number of errors that can be corrected by the code. It can be calculated as", "section_idx": 7, "section_name": "Free distance and error distribution", "target_page_ids": [ 41227 ], "anchor_spans": [ [ 37, 53 ] ] }, { "plaintext": "Since a convolutional code doesn't use blocks, processing instead a continuous bitstream, the value of t applies to a quantity of errors located relatively near to each other. That is, multiple groups of t errors can usually be fixed when they are relatively far apart.", "section_idx": 7, "section_name": "Free distance and error distribution", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Free distance can be interpreted as the minimal length of an erroneous \"burst\" at the output of a convolutional decoder. The fact that errors appear as \"bursts\" should be accounted for when designing a concatenated code with an inner convolutional code. The popular solution for this problem is to interleave data before convolutional encoding, so that the outer block (usually Reed–Solomon) code can correct most of the errors.", "section_idx": 7, "section_name": "Free distance and error distribution", "target_page_ids": [ 11763375, 4237207, 45600 ], "anchor_spans": [ [ 202, 219 ], [ 298, 308 ], [ 378, 390 ] ] }, { "plaintext": "Several algorithms exist for decoding convolutional codes. For relatively small values of k, the Viterbi algorithm is universally used as it provides maximum likelihood performance and is highly parallelizable. Viterbi decoders are thus easy to implement in VLSI hardware and in software on CPUs with SIMD instruction sets.", "section_idx": 8, "section_name": "Decoding convolutional codes", "target_page_ids": [ 775, 228015, 140806, 32823, 55359 ], "anchor_spans": [ [ 8, 17 ], [ 97, 114 ], [ 150, 168 ], [ 258, 262 ], [ 301, 305 ] ] }, { "plaintext": "Longer constraint length codes are more practically decoded with any of several sequential decoding algorithms, of which the Fano algorithm is the best known. Unlike Viterbi decoding, sequential decoding is not maximum likelihood but its complexity increases only slightly with constraint length, allowing the use of strong, long-constraint-length codes. Such codes were used in the Pioneer program of the early 1970s to Jupiter and Saturn, but gave way to shorter, Viterbi-decoded codes, usually concatenated with large Reed–Solomon error correction codes that steepen the overall bit-error-rate curve and produce extremely low residual undetected error rates.", "section_idx": 8, "section_name": "Decoding convolutional codes", "target_page_ids": [ 25258521, 434212, 25040, 45600 ], "anchor_spans": [ [ 80, 99 ], [ 125, 129 ], [ 383, 398 ], [ 521, 550 ] ] }, { "plaintext": "Both Viterbi and sequential decoding algorithms return hard decisions: the bits that form the most likely codeword. An approximate confidence measure can be added to each bit by use of the Soft output Viterbi algorithm. Maximum a posteriori (MAP) soft decisions for each bit can be obtained by use of the BCJR algorithm.", "section_idx": 8, "section_name": "Decoding convolutional codes", "target_page_ids": [ 228015, 1792433, 8846521 ], "anchor_spans": [ [ 190, 219 ], [ 221, 241 ], [ 306, 320 ] ] }, { "plaintext": "In fact, predefined convolutional codes structures obtained during scientific researches are used in the industry. This relates to the possibility to select catastrophic convolutional codes (causes larger number of errors).", "section_idx": 9, "section_name": "Popular convolutional codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An especially popular Viterbi-decoded convolutional code, used at least since the Voyager program has a constraint length of 7 and a rate r of 1/2.", "section_idx": 9, "section_name": "Popular convolutional codes", "target_page_ids": [ 47795 ], "anchor_spans": [ [ 82, 97 ] ] }, { "plaintext": "Mars Pathfinder, Mars Exploration Rover and the Cassini probe to Saturn use a of 15 and a rate of 1/6; this code performs about 2dB better than the simpler code at a cost of 256× in decoding complexity (compared to Voyager mission codes).", "section_idx": 9, "section_name": "Popular convolutional codes", "target_page_ids": [ 177323, 252908, 67941 ], "anchor_spans": [ [ 0, 15 ], [ 17, 39 ], [ 48, 61 ] ] }, { "plaintext": "The convolutional code with a constraint length of 2 and a rate of 1/2 is used in GSM as an error correction technique.", "section_idx": 9, "section_name": "Popular convolutional codes", "target_page_ids": [ 12808 ], "anchor_spans": [ [ 82, 85 ] ] }, { "plaintext": "Convolutional code with any code rate can be designed based on polynomial selection; however, in practice, a puncturing procedure is often used to achieve the required code rate. Puncturing is a technique used to make a m/n rate code from a \"basic\" low-rate (e.g., 1/n) code. It is achieved by deleting of some bits in the encoder output. Bits are deleted according to a puncturing matrix. The following puncturing matrices are the most frequently used:", "section_idx": 10, "section_name": "Punctured convolutional codes", "target_page_ids": [ 3547060 ], "anchor_spans": [ [ 179, 189 ] ] }, { "plaintext": "For example, if we want to make a code with rate 2/3 using the appropriate matrix from the above table, we should take a basic encoder output and transmit every first bit from the first branch and every bit from the second one. The specific order of transmission is defined by the respective communication standard.", "section_idx": 10, "section_name": "Punctured convolutional codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Punctured convolutional codes are widely used in the satellite communications, for example, in INTELSAT systems and Digital Video Broadcasting.", "section_idx": 10, "section_name": "Punctured convolutional codes", "target_page_ids": [ 45207, 15516, 146977 ], "anchor_spans": [ [ 53, 77 ], [ 95, 103 ], [ 116, 142 ] ] }, { "plaintext": "Punctured convolutional codes are also called \"perforated\".", "section_idx": 10, "section_name": "Punctured convolutional codes", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Simple Viterbi-decoded convolutional codes are now giving way to turbo codes, a new class of iterated short convolutional codes that closely approach the theoretical limits imposed by Shannon's theorem with much less decoding complexity than the Viterbi algorithm on the long convolutional codes that would be required for the same performance. Concatenation with an outer algebraic code (e.g., Reed–Solomon) addresses the issue of error floors inherent to turbo code designs.", "section_idx": 11, "section_name": "Turbo codes: replacing convolutional codes", "target_page_ids": [ 497535, 3474289, 11763375, 45600, 6765815 ], "anchor_spans": [ [ 65, 75 ], [ 184, 201 ], [ 345, 358 ], [ 395, 407 ], [ 432, 443 ] ] }, { "plaintext": "Quantum convolutional code", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 25573020 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "The on-line textbook: Information Theory, Inference, and Learning Algorithms, by David J.C. MacKay, discusses convolutional codes in Chapter 48.", "section_idx": 14, "section_name": "External links", "target_page_ids": [ 2679315 ], "anchor_spans": [ [ 81, 98 ] ] }, { "plaintext": "The Error Correcting Codes (ECC) Page", "section_idx": 14, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Matlab explanations", "section_idx": 14, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Fundamentals of Convolutional Decoders for Better Digital Communications", "section_idx": 14, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Convolutional codes (MIT)", "section_idx": 14, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Information Theory and Coding (TU Ilmenau), discusses convolutional codes on page 48.", "section_idx": 14, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Francis, Michael. \"Viterbi Decoder Block Decoding-Trellis Termination and Tail Biting.\" Xilinx XAPP551 v2. 0, DD (2005): 1-21.", "section_idx": 15, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Chen, Qingchun, Wai Ho Mow, and Pingzhi Fan. \"Some new results on recursive convolutional codes and their applications.\" Information Theory Workshop, 2006. ITW'06 Chengdu. IEEE. IEEE, 2006.", "section_idx": 15, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Fiebig, U-C., and Patrick Robertson. \"Soft-decision and erasure decoding in fast frequency-hopping systems with convolutional, turbo, and Reed-Solomon codes.\" IEEE Transactions on Communications 47.11 (1999): 1646-1654.", "section_idx": 15, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Bhaskar, Vidhyacharan, and Laurie L. Joiner. \"Performance of punctured convolutional codes in asynchronous CDMA communications under perfect phase-tracking conditions.\" Computers & Electrical Engineering 30.8 (2004): 573-592.", "section_idx": 15, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Modestino, J., and Shou Mui. \"Convolutional code performance in the Rician fading channel.\" IEEE Transactions on Communications 24.6 (1976): 592-606.", "section_idx": 15, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Chen, Yuh-Long, and Che-Ho Wei. \"Performance evaluation of convolutional codes with MPSK on Rician fading channels.\" IEE Proceedings F-Communications, Radar and Signal Processing. Vol. 134. No. 2. IET, 1987.", "section_idx": 15, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] } ]

[ "Error_detection_and_correction" ]

[ "Convolution code" ]

[ { "plaintext": "Copy may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Copying or the product of copying (including the plural \"copies\"); the duplication of information or an artifact", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 387960 ], "anchor_spans": [ [ 0, 7 ] ] }, { "plaintext": "Cut, copy and paste, a method of reproducing text or other data in computing", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 157115 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "File copying", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1052786 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Photocopying, a process which makes paper copies of documents and other visual images", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18935713 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Fax, a telecommunications technology used to transfer facsimile copies of documents, especially over the telephone network", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 10826 ], "anchor_spans": [ [ 0, 3 ] ] }, { "plaintext": "Facsimile, a copy or reproduction that is as true to the original source as possible", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 14632149 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Replica, a copy closely resembling the original concerning its shape and appearance", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2237442 ], "anchor_spans": [ [ 0, 7 ] ] }, { "plaintext": "Term of art in U.S. copyright law meaning a material object in which a work of authorship has been embodied, such as a book", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18938663 ], "anchor_spans": [ [ 15, 33 ] ] }, { "plaintext": " Copy (command), a shell command on DOS and Windows systems", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 17306626 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": "Copy (publishing), written content in publications, in contrast to photographs or other elements of layout. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 714335 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "The output of journalists and authors, ready for copy editing and typesetting", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 50100, 914, 343323, 169180 ], "anchor_spans": [ [ 14, 24 ], [ 30, 36 ], [ 49, 58 ], [ 66, 77 ] ] }, { "plaintext": "The output of copywriters, who are employed to write material which encourages consumers to buy goods or services.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1728077 ], "anchor_spans": [ [ 14, 24 ] ] }, { "plaintext": "Camera ready copy, term used in the commercial printing industry meaning that a document is, from a technical standpoint, ready to \"go to press\", or be printed.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 7601256 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Copy (album), the debut album of the electronica artist Mitsuki Aira", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 23391249 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Copy (musician), the Portland-based electronic music artist", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 28186736 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "\"Copy\", a procedure word or response indicating a satisfactory receipt of the last radio transmission", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9590793 ], "anchor_spans": [ [ 10, 24 ] ] }, { "plaintext": "COPY, a COBOL keyword", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 28115039 ], "anchor_spans": [ [ 14, 21 ] ] }, { "plaintext": " Copy and paste (disambiguation)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 56484870 ], "anchor_spans": [ [ 1, 32 ] ] }, { "plaintext": " Copyist", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 3120054 ], "anchor_spans": [ [ 1, 8 ] ] }, { "plaintext": " Copyright", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 5278 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": "Copy editing", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 343323 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": " Duplication (disambiguation)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1745029 ], "anchor_spans": [ [ 1, 29 ] ] } ]

[]

[]

[ { "plaintext": "In telecommunication, a cord circuit is a switchboard circuit in which a plug-terminated cord is used to establish connections manually between user lines or between trunks and user lines. A number of cord circuits are furnished as part of the switchboard position equipment. The cords may be referred to as front cord and rear cord or trunk cord and station cord. In modern cordless switchboards, the cord-circuit function is switch operated and may be programmable.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 28427, 8707643, 2052479, 5783 ], "anchor_spans": [ [ 3, 20 ], [ 42, 53 ], [ 54, 61 ], [ 144, 148 ], [ 454, 466 ] ] }, { "plaintext": "In early and middle 20th century telephone exchanges this task was done by a supervisory relay set known variously as junctor circuit or district junctor. Later designs made it a function of the trunk circuit or absorbed it into software.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26668156, 18168568, 18168568 ], "anchor_spans": [ [ 33, 51 ], [ 118, 133 ], [ 137, 153 ] ] }, { "plaintext": "Switched loop", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 41765 ], "anchor_spans": [ [ 0, 13 ] ] } ]

[ "Telephony_equipment" ]

[]

[ { "plaintext": "Core or cores may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Core (anatomy), everything except the appendages", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 7974163 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Core (manufacturing), used in casting and molding", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 23805828 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Core (optical fiber), the signal-carrying portion of an optical fiber", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 20565861 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Core, the central part of a fruit", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 10843 ], "anchor_spans": [ [ 29, 34 ] ] }, { "plaintext": " Hydrophobic core, the interior zone of a protein", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 1020643 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Nuclear reactor core, a portion containing the fuel components", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 3112392 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Pit (nuclear weapon) or core, the fissile material in a nuclear weapon", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 25965010 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Semiconductor intellectual property core (IP core), is a unit of design in ASIC/FPGA electronics and IC manufacturing", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 1785216 ], "anchor_spans": [ [ 1, 41 ] ] }, { "plaintext": " Atomic core, an atom with no valence electrons", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 5129473 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Core sample, in Earth science, a sample obtained by coring", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 3086453 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Ice core", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 426456 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Core, the central part of a galaxy; see Mass deficit", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 1349163 ], "anchor_spans": [ [ 41, 53 ] ] }, { "plaintext": " Core (anticline), the central part of an anticline or syncline", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 1345538 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Planetary core, the center of a planet", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 864017 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Earth's inner core", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 2939202 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Earth's outer core", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 146249 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Stellar core, the region of a star where nuclear fusion takes place", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 38815769 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Solar core,", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 4640562 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Core Animation, a data visualization API used in macOS", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 6317768 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Core dump, the recorded state of a running program", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 49721 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Intel Core, a family of single-core and multi-core 32-bit and 64-bit CPUs released by Intel", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 24538587 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Magnetic core, in electricity and electronics, ferromagnetic material around which wires are wound", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 1516916 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Magnetic-core memory, the primary memory technology used before semiconductor memory", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 78029 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Central processing unit (CPU), called a core", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 5218 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Multi-core processor, a microprocessor with multiple CPUs on one integrated circuit chip", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 3503207 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Server Core, a minimalist Microsoft Windows Server installation option", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 38904853 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Core (game theory), the collection of stable allocations that no coalition can improve upon", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 1886266 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Core (graph theory), the homomorphically minimal subgraph of a graph", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 9908503 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Core (group theory), an object in group theory", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 893516 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Core of a triangulated category", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 1679700 ], "anchor_spans": [ [ 11, 32 ] ] }, { "plaintext": " Core, an essential domain of a closed operator; see Unbounded operator", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 1422584 ], "anchor_spans": [ [ 53, 71 ] ] }, { "plaintext": " Core, a radial kernel of a subset of a vector space; see Algebraic interior", "section_idx": 1, "section_name": "Science and technology", "target_page_ids": [ 30823252 ], "anchor_spans": [ [ 58, 76 ] ] }, { "plaintext": " Core (novel), a 1993 science fiction novel by Paul Preuss", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 2894733 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Core (radio station), a defunct digital radio station in the United Kingdom", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 2088360 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " 90.3 The Core RLC-WVPH, a radio station in Piscataway, New Jersey, US", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 2833639 ], "anchor_spans": [ [ 19, 23 ] ] }, { "plaintext": " C.O.R.E. (video game), a 2009 NDS game", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 19947450 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Core (video game), a video game with integrated game creation system", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 65420222 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " \"CORE\", an area in the Underground in the video game Undertale", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 47952646 ], "anchor_spans": [ [ 54, 63 ] ] }, { "plaintext": " \"The Core\", an episode of The Transformers cartoon", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 3034761 ], "anchor_spans": [ [ 27, 43 ] ] }, { "plaintext": " Cores (film), a 2012 film", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 39291315 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " The Core, a 2003 science fiction film", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 210155 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " The Core, the 2006–2007 name for the programming block on Five currently known as Shake!", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 11084351 ], "anchor_spans": [ [ 83, 89 ] ] }, { "plaintext": " Core (band), a stoner rock band", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 13935414 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Core (Stone Temple Pilots album), 1992", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 354908 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Core (Persefone album), 2006", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 8464721 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " \"Core\", a song by Susumu Hirasawa from Paranoia Agent Original Soundtrack", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 5397692 ], "anchor_spans": [ [ 41, 75 ] ] }, { "plaintext": " \"The Core\", a song from Eric Clapton's 1977 album Slowhand", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 195938 ], "anchor_spans": [ [ 51, 59 ] ] }, { "plaintext": " \"CORE\", a track from the soundtrack of the 2015 video game Undertale by Toby Fox", "section_idx": 2, "section_name": "Arts, entertainment and media", "target_page_ids": [ 67024346 ], "anchor_spans": [ [ 22, 36 ] ] }, { "plaintext": " Core International, a defunct American computer and technology corporation", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 26923975 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Core Design, a videogame developer best known for the Tomb Raider series", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 1782344 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Coordenadoria de Recursos Especiais, Brazilian state police SWAT team", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 19370341 ], "anchor_spans": [ [ 1, 36 ] ] }, { "plaintext": " Digestive Disorders Foundation, working name Core", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 1490654 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Center for Operations Research and Econometrics at the Université catholique de Louvain in Belgium", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 50227566 ], "anchor_spans": [ [ 1, 48 ] ] }, { "plaintext": " Central Organisation for Railway Electrification, an organization in India", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 12436671 ], "anchor_spans": [ [ 1, 49 ] ] }, { "plaintext": " China Open Resources for Education, an OpenCourseWare organization in China", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 17815558 ], "anchor_spans": [ [ 1, 35 ] ] }, { "plaintext": " Congress of Racial Equality, United States civil rights organization", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 203908 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " CORE (research service), a UK-based aggregator of open access content ", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 44990267 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " C.O.R.E., a computer animation studio", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 4831623 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " CORE System Trust, see CORE-OM", "section_idx": 3, "section_name": "Organizations", "target_page_ids": [ 58716099 ], "anchor_spans": [ [ 24, 31 ] ] }, { "plaintext": " Core, San Diego, a neighborhood in California", "section_idx": 4, "section_name": "Places", "target_page_ids": [ 9201420 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Core, West Virginia", "section_idx": 4, "section_name": "Places", "target_page_ids": [ 25245747 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Core Banks, North Carolina", "section_idx": 4, "section_name": "Places", "target_page_ids": [ 28201648 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Core Sound, North Carolina", "section_idx": 4, "section_name": "Places", "target_page_ids": [ 3919028 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Corés, a parish in Spain", "section_idx": 4, "section_name": "Places", "target_page_ids": [ 22360104 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " The Core Shopping Centre (Calgary), Alberta, Canada ", "section_idx": 4, "section_name": "Places", "target_page_ids": [ 27364468 ], "anchor_spans": [ [ 1, 35 ] ] }, { "plaintext": " The Core, a shopping centre in Leeds, England, on the site of Schofields", "section_idx": 4, "section_name": "Places", "target_page_ids": [ 3740792 ], "anchor_spans": [ [ 63, 73 ] ] }, { "plaintext": " Earl Lemley Core (1902–1984), West Virginia botanist", "section_idx": 5, "section_name": "People", "target_page_ids": [ 22888855 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Ericson Core, American director and cinematographer", "section_idx": 5, "section_name": "People", "target_page_ids": [ 50395138 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Core (architecture)", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 48657205 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Co-ordinated On-line Record of Electors, central database in the United Kingdom", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 4459775 ], "anchor_spans": [ [ 1, 40 ] ] }, { "plaintext": " Coree or Cores, a Native American tribe", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 3918958 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " Korah, a biblical figure", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 608565 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " Leadership core, concept in Chinese politics", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 52131956 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Persephone, a Greek goddess also known as Kore or Cora (Greek κόρη = daughter)", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 24253 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Core countries, in dependency theory, an industrialized country on which peripheral countries depend", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 1582312 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Core curriculum, in education, an essential part of the curriculum", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 479983 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Lithic core, in archaeology, a stone artifact left over from toolmaking", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 140992 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " CORE (Clinical Outcomes in Routine Use) System, see CORE-OM", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 58716099 ], "anchor_spans": [ [ 53, 60 ] ] }, { "plaintext": " CORE (disambiguation)", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 764251 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Corre (disambiguation)", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 29177500 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Nucleus (disambiguation)", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 21491 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Corium (disambiguation)", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 5312136 ], "anchor_spans": [ [ 1, 24 ] ] } ]

[]

[]

[ { "plaintext": "A corner reflector is a retroreflector consisting of three mutually perpendicular, intersecting flat surfaces, which reflects waves directly towards the source, but translated. The three intersecting surfaces often have square shapes. Radar corner reflectors made of metal are used to reflect radio waves from radar sets. Optical corner reflectors, called corner cubes or cube corners, made of three-sided glass prisms, are used in surveying and laser ranging.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 59853, 76944, 41604289, 33516, 204682, 25676, 282998, 60891, 1461372 ], "anchor_spans": [ [ 24, 38 ], [ 68, 81 ], [ 83, 95 ], [ 126, 130 ], [ 165, 175 ], [ 312, 317 ], [ 414, 419 ], [ 434, 443 ], [ 448, 461 ] ] }, { "plaintext": "The incoming ray is reflected three times, once by each surface, which results in a reversal of direction. To see this, the three corresponding normal vectors of the corner's perpendicular sides can be considered to form a basis (a rectangular coordinate system) (x, y, z) in which to represent the direction of an arbitrary incoming ray, . When the ray reflects from the first side, say x, the ray's x component, a, is reversed to −a while the y and z components are unchanged, resulting in a direction of . Similarly, when reflected from side y and finally from side z, the b and c components are reversed. Therefore, the ray direction goes from to to to , and it leaves the corner reflector with all three components of direction exactly reversed. The distance travelled, relative to a plane normal to the direction of the rays, is also equal for any ray entering the reflector, regardless of the location where it first reflects.", "section_idx": 1, "section_name": "Principle", "target_page_ids": [ 18420, 7706 ], "anchor_spans": [ [ 225, 230 ], [ 234, 263 ] ] }, { "plaintext": "Radar corner reflectors are designed to reflect the microwave radio waves emitted by radar sets back toward the radar antenna. This causes them to show a strong \"return\" on radar screens. A simple corner reflector consists of three conducting sheet metal or screen surfaces at 90° angles to each other, attached to one another at the edges, forming a \"corner\". These reflect radio waves coming from in front of them back parallel to the incoming beam. To create a corner reflector that will reflect radar waves coming from any direction, 8 corner reflectors are placed back-to-back in an octahedron (diamond) shape. The reflecting surfaces must be larger than several wavelengths of the radio waves to function.", "section_idx": 2, "section_name": "In radar", "target_page_ids": [ 20097, 98132, 25676, 22458, 33125 ], "anchor_spans": [ [ 52, 61 ], [ 62, 73 ], [ 85, 90 ], [ 592, 602 ], [ 673, 683 ] ] }, { "plaintext": "In maritime navigation they are placed on bridge abutments, buoys, ships and, especially, lifeboats, to ensure that these show up strongly on ship radar screens. Corner reflectors are placed on the vessel's masts at a height of at least above sea level (giving them an approximate minimum horizon distance of ). Marine radar uses X-band microwaves with wavelengths of , so small reflectors less than across are used. In aircraft navigation, corner reflectors are installed on rural runways, to make them show up on aircraft radar.", "section_idx": 2, "section_name": "In radar", "target_page_ids": [ 3397, 145773, 27008, 14709004, 48910, 25643892, 553950, 165094 ], "anchor_spans": [ [ 42, 48 ], [ 60, 64 ], [ 67, 71 ], [ 90, 99 ], [ 291, 298 ], [ 315, 327 ], [ 333, 339 ], [ 487, 493 ] ] }, { "plaintext": "In optics, corner reflectors typically consist of three mirrors or reflective prism faces which return an incident light beam in the opposite direction. In surveying, retroreflector prisms are commonly used as targets for long-range electronic distance measurement using a total station.", "section_idx": 3, "section_name": "In optics", "target_page_ids": [ 22483, 20545, 282998, 1612888, 60891, 59853, 683327 ], "anchor_spans": [ [ 3, 9 ], [ 56, 62 ], [ 78, 83 ], [ 115, 125 ], [ 156, 165 ], [ 167, 181 ], [ 273, 286 ] ] }, { "plaintext": "Five arrays of optical corner reflectors have been placed on the Moon for use by Lunar Laser Ranging experiments observing a laser's time-of-flight to measure the Moon's orbit more precisely than was possible before. The three largest were placed by NASA as part of the Apollo program, and the Soviet Union built two smaller ones into the Lunokhod rovers.", "section_idx": 3, "section_name": "In optics", "target_page_ids": [ 19331, 148634, 17556, 377876, 18426568, 1461, 26779, 45114 ], "anchor_spans": [ [ 65, 69 ], [ 81, 111 ], [ 125, 130 ], [ 133, 147 ], [ 251, 255 ], [ 271, 285 ], [ 295, 307 ], [ 340, 355 ] ] }, { "plaintext": "Automobile and bicycle tail lights are molded with arrays of small corner reflectors, with different sections oriented for viewing from different angles. Reflective paint for visibility at night usually contains retroreflective spherical beads.", "section_idx": 3, "section_name": "In optics", "target_page_ids": [ 13673345, 3973, 23776, 59853 ], "anchor_spans": [ [ 0, 10 ], [ 15, 22 ], [ 166, 171 ], [ 213, 244 ] ] }, { "plaintext": "Thin plastic with microscopic corner reflector structures can be used as tape, on signs, or sewn or molded onto clothing.", "section_idx": 3, "section_name": "In optics", "target_page_ids": [ 9972860, 38180 ], "anchor_spans": [ [ 73, 77 ], [ 112, 120 ] ] }, { "plaintext": "Corner reflectors can also occur accidentally. Tower blocks with balconies are often accidental corner reflectors for sound and return a distinctive echo to an observer making a sharp noise, such as a hand clap, nearby. Similarly, in radar interpretation, an object that has multiple reflections from smooth surfaces produces a radar return of greater magnitude than might be expected from the physical size of the object. This effect was put to use on the ADM-20 Quail, a small missile which had the same radar cross section as a B-52.", "section_idx": 4, "section_name": "Other examples", "target_page_ids": [ 118767, 172080, 2497001, 740680, 18933037 ], "anchor_spans": [ [ 47, 58 ], [ 65, 74 ], [ 457, 469 ], [ 506, 525 ], [ 531, 535 ] ] }, { "plaintext": "Corner Reflector Antennas", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Corner Reflector for WiFi", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Mirrors", "Radar" ]

[ "radar reflector" ]

[ { "plaintext": "Cosmic noise, also known as galactic radio noise, is not actually sound, but a physical phenomenon derived from outside of the Earth's atmosphere. It can be detected through a radio receiver, which is an electronic device that receives radio waves and converts the information given by them to an audible form. Its characteristics are comparable to those of thermal noise. Cosmic noise occurs at frequencies above about 15MHz when highly directional antennas are pointed toward the Sun or other regions of the sky, such as the center of the Milky Way Galaxy. Celestial objects like quasars, which are super dense objects far from Earth, emit electromagnetic waves in their full spectrum, including radio waves. The fall of a meteorite can also be heard through a radio receiver; the falling object burns from friction with the Earth's atmosphere, ionizing surrounding gases and producing radio waves. Cosmic microwave background radiation (CMBR) from outer space is also a form of cosmic noise. CMBR is thought to be a relic of the Big Bang, and pervades the space almost homogeneously over the entire celestial sphere. The bandwidth of the CMBR is wide, though the peak is in the microwave range.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 177602, 491851, 98132, 182745, 14121, 373352, 25239, 19937, 98132, 7376, 177602, 4116, 48239, 3967 ], "anchor_spans": [ [ 112, 145 ], [ 176, 190 ], [ 236, 246 ], [ 358, 371 ], [ 422, 425 ], [ 527, 557 ], [ 582, 588 ], [ 725, 734 ], [ 888, 899 ], [ 901, 938 ], [ 951, 962 ], [ 1032, 1040 ], [ 1102, 1118 ], [ 1124, 1133 ] ] }, { "plaintext": "Karl Jansky, an American physicist and radio engineer, first discovered radio waves from the Milky Way in August, 1931. At Bell Telephone Laboratories in 1932, Jansky built an antenna designed to receive radio waves at a frequency of 20.5MHz, which is a wavelength of approximately 14.6meters.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 180079, 98132, 2589714, 3712, 14121 ], "anchor_spans": [ [ 0, 11 ], [ 72, 82 ], [ 93, 102 ], [ 123, 150 ], [ 238, 241 ] ] }, { "plaintext": "After recording signals with this antenna for several months, Jansky categorized them into three types: nearby thunderstorms, distant thunderstorms, and a faint steady hiss of an unknown origin. He discovered the location of maximum intensity rose and fell once a day, which led him to believe he was detecting radiation from the Sun.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 26751 ], "anchor_spans": [ [ 330, 333 ] ] }, { "plaintext": "A few months went by following this signal thought to be from the Sun, and Jansky found that the brightest point moved away from the Sun and concluded the cycle repeated every 23 hours and 56 minutes. After this discovery, Jansky concluded the radiation was coming from the Milky Way and was strongest in the direction of the center of the galaxy.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 2589714, 12558 ], "anchor_spans": [ [ 274, 283 ], [ 340, 346 ] ] }, { "plaintext": "Jansky's work helped to distinguish between the radio sky and the optical sky. The optical sky is what is seen by the human eye, whereas the radio sky consists of daytime meteors, solar bursts, quasars, and gravitational waves.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 22483 ], "anchor_spans": [ [ 66, 73 ] ] }, { "plaintext": "Later in 1963, American physicist and radio astronomer Arno Allan Penzias (born April 26, 1933) discovered cosmic microwave background radiation. Penzias's discovery of cosmic microwave background radiation helped establish the Big Bang theory of cosmology. Penzias and his partner, Robert Woodrow Wilson worked together on ultra-sensitive cryogenic microwave receivers, originally intended for radio astronomy observations. In 1964, upon creating their most sensitive antenna/receiver system, the Holmdel Horn Antenna, the two discovered a radio noise they could not explain. After further investigation, Penzias contacted Robert Dicke, who suggested it could be the background radiation predicted by cosmological theories, a radio remnant of the Big Bang. Penzias and Wilson won the Nobel Prize in Physics in 1978.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 318516, 7376, 4116, 318514, 20097, 639767, 737819, 4116, 52497 ], "anchor_spans": [ [ 55, 73 ], [ 108, 145 ], [ 230, 238 ], [ 285, 306 ], [ 352, 361 ], [ 500, 520 ], [ 626, 638 ], [ 750, 758 ], [ 787, 809 ] ] }, { "plaintext": "The Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) is a device designed to observe the transition out of the \"cosmic dark ages\" as the first stars ignite in nuclear fusion and the universe begins to resemble its current form.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 21026017, 31880 ], "anchor_spans": [ [ 4, 73 ], [ 212, 220 ] ] }, { "plaintext": "ARCADE consists of 7 precision radiometers carried to an altitude of over 35km (21miles) by a scientific research balloon. The device measures the tiny heating of the early universe by the first generation of stars and galaxies to form after the Big Bang.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 839718, 2149971, 31880, 4116 ], "anchor_spans": [ [ 31, 41 ], [ 94, 121 ], [ 173, 181 ], [ 246, 254 ] ] }, { "plaintext": "Cosmic noise refers to the background radio frequency radiation from galactic sources, which have constant intensity during geomagnetically quiet periods.", "section_idx": 2, "section_name": "Sources of cosmic noise", "target_page_ids": [ 42852, 12558, 146983 ], "anchor_spans": [ [ 27, 53 ], [ 69, 85 ], [ 124, 135 ] ] }, { "plaintext": "Cosmic noise can be traced from solar flares, which are sudden explosive releases of stored magnetic energy in the atmosphere of the Sun, causing sudden brightening of the photosphere. Solar flares can last from a few minutes to several hours.", "section_idx": 2, "section_name": "Sources of cosmic noise", "target_page_ids": [ 54648, 23971781, 38979 ], "anchor_spans": [ [ 32, 44 ], [ 92, 107 ], [ 172, 183 ] ] }, { "plaintext": "During solar flare events, particles and electromagnetic emissions can affect Earth's atmosphere by fluctuating the level of ionization in the Earth's ionosphere. Increased ionization results in absorption of the cosmic radio noise as it passes through the ionosphere.", "section_idx": 2, "section_name": "Sources of cosmic noise", "target_page_ids": [ 9228, 59611, 15097 ], "anchor_spans": [ [ 78, 83 ], [ 125, 135 ], [ 151, 161 ] ] }, { "plaintext": "Solar wind is a flux of particles, protons and electrons together with nuclei of heavier elements in smaller numbers, that are accelerated by the high temperatures of the solar corona to velocities large enough to allow them to escape from the Sun's gravitational field.", "section_idx": 2, "section_name": "Sources of cosmic noise", "target_page_ids": [ 28538, 23317, 9476, 19916559, 7839 ], "anchor_spans": [ [ 0, 10 ], [ 35, 41 ], [ 47, 55 ], [ 71, 77 ], [ 171, 183 ] ] }, { "plaintext": "Solar wind causes sudden bursts of cosmic noise absorption in the Earth's ionosphere. These bursts can only be detected only if the magnitude of the geomagnetic field perturbation caused by the solar wind shock is large enough.", "section_idx": 2, "section_name": "Sources of cosmic noise", "target_page_ids": [], "anchor_spans": [] } ]

[ "Astronomical_radio_sources", "Noise" ]

[ "galactic radio noise" ]

[ { "plaintext": "A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK). It was invented by John P. Costas at General Electric in the 1950s. Its invention was described as having had \"a profound effect on modern digital communications\".", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41548, 153217, 5768230, 20637, 41701, 41551, 41551, 18476151, 12730 ], "anchor_spans": [ [ 19, 36 ], [ 75, 82 ], [ 93, 101 ], [ 126, 136 ], [ 158, 166 ], [ 230, 234 ], [ 236, 240 ], [ 262, 276 ], [ 280, 296 ] ] }, { "plaintext": "The primary application of Costas loops is in wireless receivers. Its advantage over other PLL-based detectors is that at small deviations the Costas loop error voltage is as compared to . This translates to double the sensitivity and also makes the Costas loop uniquely suited for tracking Doppler-shifted carriers, especially in OFDM and GPS receivers.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8724, 22691, 17800413 ], "anchor_spans": [ [ 292, 307 ], [ 332, 336 ], [ 341, 353 ] ] }, { "plaintext": "In the classical implementation of a Costas loop, a local voltage-controlled oscillator (VCO) provides quadrature outputs, one to each of two phase detectors, e.g., product detectors. The same phase of the input signal is also applied to both phase detectors, and the output of each phase detector is passed through a low-pass filter. The outputs of these low-pass filters are inputs to another phase detector, the output of which passes through a noise-reduction filter before being used to control the voltage-controlled oscillator. The overall loop response is controlled by the two individual low-pass filters that precede the third phase detector, while the third low-pass filter serves a trivial role in terms of gain and phase margin.", "section_idx": 1, "section_name": "Classical implementation", "target_page_ids": [ 599563, 24047, 359281, 345141, 275871, 359281, 56484 ], "anchor_spans": [ [ 58, 87 ], [ 103, 113 ], [ 142, 156 ], [ 165, 181 ], [ 212, 218 ], [ 283, 297 ], [ 318, 333 ] ] }, { "plaintext": "The above figure of a Costas loop is drawn under the \"locked\" state, where the VCO frequency and the incoming carrier frequency have become the same due to the Costas loop process. The figure does not represent the \"unlocked\" state.", "section_idx": 1, "section_name": "Classical implementation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the simplest case . Therefore, does not affect the input of the noise-reduction filter.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The carrier and voltage-controlled oscillator (VCO) signals are periodic oscillations with high-frequencies .", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [ 599563 ], "anchor_spans": [ [ 16, 45 ] ] }, { "plaintext": "The block is an analog multiplier.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [ 344731 ], "anchor_spans": [ [ 17, 34 ] ] }, { "plaintext": "A linear filter can be described mathematically by a system of linear differential equations:", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [ 9975 ], "anchor_spans": [ [ 2, 15 ] ] }, { "plaintext": "where is a constant matrix, is a state vector of the filter, and are constant vectors.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The model of a VCO is usually assumed to be linear:", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where is the free-running frequency of the VCO and is the VCO gain factor. Similarly, it is possible to consider various nonlinear models of VCO.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Suppose that the frequency of the master generator is constant", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Equation of VCO and equation of filter yield", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The system is non-autonomous and rather tricky for investigation.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [ 38838646 ], "anchor_spans": [ [ 14, 28 ] ] }, { "plaintext": "In the simplest case, when", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The standard engineering assumption is that the filter removes the upper sideband frequency from the input but leaves the lower sideband without change. Thus it is assumed that the VCO input is This makes a Costas loop equivalent to a phase-locked loop with phase detector characteristic corresponding to the particular waveforms and of the input and VCO signals. It can be proved that filter outputs in the time and phase-frequency domains are almost equal.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [ 41548, 34111257 ], "anchor_spans": [ [ 236, 253 ], [ 259, 288 ] ] }, { "plaintext": "Thus it is possible to study the simpler autonomous system of differential equations", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [ 312398 ], "anchor_spans": [ [ 41, 58 ] ] }, { "plaintext": ".", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The Krylov–Bogoliubov averaging method allows one to prove that solutions of non-autonomous and autonomous equations are close under some assumptions.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [ 21291593 ], "anchor_spans": [ [ 4, 38 ] ] }, { "plaintext": "Thus, the Costas loop block diagram in the time domain can be asymptotically changed to the block diagram on the level of phase-frequency relations.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The transition to the analysis of an autonomous dynamical model of the Costas loop (in place of the non-autonomous one) allows one to overcome the difficulties related to modeling the Costas loop in the time domain, where one has to simultaneously observe a very fast time scale of the input signals and slow time scale of signal's phase. This idea makes it possible to calculate core performance characteristics - hold-in, pull-in, and lock-in ranges.", "section_idx": 2, "section_name": "Mathematical models", "target_page_ids": [ 47611264 ], "anchor_spans": [ [ 415, 451 ] ] }, { "plaintext": "The classical Costas loop will work towards making the phase difference between the carrier and the VCO become a small, ideally zero, value. The small phase difference implies that frequency lock has been achieved.", "section_idx": 3, "section_name": "Frequency acquisition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The classical Costas loop can be adapted to QPSK modulation for higher data rates.", "section_idx": 4, "section_name": "QPSK Costas loop", "target_page_ids": [ 41551 ], "anchor_spans": [ [ 44, 48 ] ] }, { "plaintext": "The input QPSK signal is as follows", "section_idx": 4, "section_name": "QPSK Costas loop", "target_page_ids": [ 41551 ], "anchor_spans": [ [ 10, 14 ] ] }, { "plaintext": "Inputs of low-pass filters LPF1 and LPF2 are", "section_idx": 4, "section_name": "QPSK Costas loop", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "After synchronization,", "section_idx": 4, "section_name": "QPSK Costas loop", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "the outputs of LPF1 and LPF2 are used to get demodulated data ( and ). To adjust the frequency of the VCO to the reference frequency, signals and are limited and cross-multiplied:", "section_idx": 4, "section_name": "QPSK Costas loop", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Then the signal is filtered by the loop filter and forms the tuning signal for the VCO , similar to BPSK Costas loop. Thus, QPSK Costas can be described by a system of ordinary differential equations:", "section_idx": 4, "section_name": "QPSK Costas loop", "target_page_ids": [ 32742753 ], "anchor_spans": [ [ 169, 200 ] ] }, { "plaintext": "Here are parameters of LPF1 and LPF2 and are parameters of the loop filter.", "section_idx": 4, "section_name": "QPSK Costas loop", "target_page_ids": [], "anchor_spans": [] } ]

[ "Electronic_oscillators", "Communication_circuits" ]

[]

[ { "plaintext": "A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both. In a more general context, a coupling can also be a mechanical device that serves to connect the ends of adjacent parts or objects. Couplings do not normally allow disconnection of shafts during operation, however there are torque-limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3764368 ], "anchor_spans": [ [ 483, 498 ] ] }, { "plaintext": "Shaft couplings are used in machinery for several purposes. A primary function is to transfer power from one end to another end (ex: motor transfer power to pump through coupling).", "section_idx": 1, "section_name": "Uses", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Other common uses:", "section_idx": 1, "section_name": "Uses", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " To alter the vibration characteristics of rotating units", "section_idx": 1, "section_name": "Uses", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " To connect the driving and the driven part", "section_idx": 1, "section_name": "Uses", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " To introduce protection", "section_idx": 1, "section_name": "Uses", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " To reduce the transmission of shock loads from one shaft to another", "section_idx": 1, "section_name": "Uses", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " To slip when overload occurs", "section_idx": 1, "section_name": "Uses", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A beam coupling, also known as helical coupling, is a flexible coupling for transmitting torque between two shafts while allowing for angular misalignment, parallel offset and even axial motion, of one shaft relative to the other. This design utilizes a single piece of material and becomes flexible by removal of material along a spiral path resulting in a curved flexible beam of helical shape. Since it is made from a single piece of material, the beam style coupling does not exhibit the backlash found in some multi-piece couplings. Another advantage of being an all machined coupling is the possibility to incorporate features into the final product while still keep the single piece integrity.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 10058792 ], "anchor_spans": [ [ 494, 502 ] ] }, { "plaintext": "Changes to the lead of the helical beam provide changes to misalignment capabilities as well as other performance characteristics such as torque capacity and torsional stiffness. It is even possible to have multiple starts within the same helix.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The material used to manufacture the beam coupling also affects its performance and suitability for specific applications such as food, medical and aerospace. Materials are typically aluminum alloy and stainless steel, but they can also be made in acetal, maraging steel and titanium. The most common applications are attaching rotary encoders to shafts and motion control for robotics.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 1123769, 1359497, 30040, 741020, 20903754 ], "anchor_spans": [ [ 248, 254 ], [ 256, 270 ], [ 275, 283 ], [ 328, 342 ], [ 377, 385 ] ] }, { "plaintext": "Beam couplings can be known by various names depending upon industry. These names include flexible coupling, flexible beam coupling, flexible shaft coupling, flexure, helical coupling, and shaft coupling.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The primary benefit to using a flexible beam coupling to join two rotating shafts is to reducing vibration and reaction loads which in turn will reduce overall wear and tear on machinery and prolong equipment life.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Bush pin flange coupling is used for slightly imperfect alignment of the two shafts.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This is modified form of the protected type flange coupling. This type of coupling has pins and it works with coupling bolts. The rubber or leather bushes are used over the pins. The coupling has two halves dissimilar in construction. The pins are rigidly fastened by nuts to one of the flange and kept loose on the other flange. This coupling is used to connect shafts which have a small parallel misalignment, angular misalignment or axial misalignment. In this coupling the rubber bushing absorbs shocks and vibration during its operations. This type of coupling is mostly used to couple electric motors and machines.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "There are various types of constant-velocity (CV) couplings: Rzeppa joint, Double cardan joint, and Thompson coupling.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 934672, 934672, 934672 ], "anchor_spans": [ [ 61, 73 ], [ 75, 88 ], [ 100, 117 ] ] }, { "plaintext": "In this coupling, the muff or sleeve is made into two halves parts of the cast iron and they are joined by means of mild steel studs or bolts. The advantages of this coupling is that assembling or disassembling of the coupling is possible without changing the position of the shaft. This coupling is used for heavy power transmission at moderate speed.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Diaphragm couplings transmit torque from the outside diameter of a flexible plate to the inside diameter, across the spool or spacer piece, and then from inside to outside diameter. The deforming of a plate or series of plates from I.D. to O.D accomplishes the misalignment.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Disc couplings transmit torque from a driving to a driven bolt tangentially on a common bolt circle. Torque is transmitted between the bolts through a series of thin, stainless steel discs assembled in a pack. Misalignment is accomplished by deforming of the material between the bolts.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An elastic coupling transmits torque or other load by means of an elastic component. One example is the coupling used to join a windsurfing rig (sail, mast, and components) to the sailboard. In windsurfing terminology it is usually called a \"universal joint\", but modern designs are usually based on a strong flexible material, and better technically described as an elastic coupling. They can be tendon or hourglass-shaped, and are constructed of a strong and durable elastic material. In this application, the coupling does not transmit torque, but instead transmits sail-power to the board, creating thrust (some portion of sail-power is also transmitted through the rider's body).", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 222354, 37892 ], "anchor_spans": [ [ 128, 139 ], [ 603, 609 ] ] }, { "plaintext": "Flexible couplings are usually used to transmit torque from one shaft to another when the two shafts are slightly misaligned. They can accommodate varying degrees of misalignment up to 1.5° and some parallel misalignment. They can also be used for vibration damping or noise reduction. In rotating shaft applications a flexible coupling can protect the driving and driven shaft components (such as bearings) from the harmful effects of conditions such as misaligned shafts, vibration, shock loads, and thermal expansion of the shafts or other components.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 30400 ], "anchor_spans": [ [ 48, 54 ] ] }, { "plaintext": "At first, flexible couplings separate into two essential groups, metallic and elastomeric.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Metallic types utilize freely fitted parts that roll or slide against one another or, on the other hand, non-moving parts that bend to take up misalignment.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Elastomeric types, then again, gain flexibility from resilient, non-moving, elastic or plastic elements transmitting torque between metallic hubs.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A gear coupling is a mechanical device for transmitting torque between two shafts that are not collinear. It consists of a flexible joint fixed to each shaft. The two joints are connected by a third shaft, called the spindle.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 30400, 946975 ], "anchor_spans": [ [ 56, 62 ], [ 95, 104 ] ] }, { "plaintext": "Each joint consists of a 1:1 gear ratio internal/external gear pair. The tooth flanks and outer diameter of the external gear are crowned to allow for angular displacement between the two gears. Mechanically, the gears are equivalent to rotating splines with modified profiles. They are called gears because of the relatively large size of the teeth.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 1956881, 82916, 65926, 16465514 ], "anchor_spans": [ [ 29, 39 ], [ 58, 62 ], [ 151, 171 ], [ 238, 253 ] ] }, { "plaintext": "Gear couplings and universal joints are used in similar applications. Gear couplings have higher torque densities than universal joints designed to fit a given space while universal joints induce lower vibrations. The limit on torque density in universal joints is due to the limited cross sections of the cross and yoke. The gear teeth in a gear coupling have high backlash to allow for angular misalignment. The excess backlash can contribute to vibration.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 144948, 842236, 20646772, 1337370, 10058792 ], "anchor_spans": [ [ 19, 34 ], [ 97, 113 ], [ 202, 211 ], [ 284, 298 ], [ 366, 374 ] ] }, { "plaintext": "Gear couplings are generally limited to angular misalignments, i.e., the angle of the spindle relative to the axes of the connected shafts, of 4–5°. Universal joints are capable of higher misalignments.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Single joint gear couplings are also used to connect two nominally coaxial shafts. In this application the device is called a gear-type flexible, or flexible coupling. The single joint allows for minor misalignments such as installation errors and changes in shaft alignment due to operating conditions. These types of gear couplings are generally limited to angular misalignments of 1/4–1/2°.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 40972 ], "anchor_spans": [ [ 149, 166 ] ] }, { "plaintext": "A grid coupling is composed of two shaft hubs, a metallic grid spring, and a split cover kit. Torque is transmitted between the two coupling shaft hubs through the metallic grid spring element.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Like metallic gear and disc couplings, grid couplings have a high torque density. A benefit of grid couplings, over either gear or disc couplings, is the ability their grid coupling spring elements have to absorb and spread peak load impact energy over time. This reduces the magnitude of peak loads and offers some vibration dampening capability. A negative of the grid coupling design is that it generally is very limited in its ability to accommodate the misalignment.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 842236 ], "anchor_spans": [ [ 66, 80 ] ] }, { "plaintext": "Highly flexible couplings are installed when resonance or torsional vibration might be an issue, since they are designed to eliminate torsional vibration problems and to balance out shock impacts.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "They are used in installations where the systems requires a high level of torsional flexibility and misalignment capacity.This type of coupling provides an effective damping of torsional vibrations, and high displacement capacity, which protects the drive. The design of the highly flexible elastic couplings makes assembly easier. These couplings also compensate shaft displacements (radial, axial and angular) and the torque is transmitted in shear. Depending on the size and stiffness of the coupling, the flexible part may be single and/or multi row.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Hirth joints use tapered teeth on two shaft ends meshed together to transmit torque.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Jaw coupling is also known as spider or Lovejoy coupling.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A magnetic coupling uses magnetic forces to transmit the power from one shaft to another without any contact. This allows for full medium separation. Therefore, can provide the ability to hermetically separate two areas whilst continuing to transmit mechanical power from one to the other making these couplings ideal for applications where prevention of cross contamination is essential.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 5317262 ], "anchor_spans": [ [ 2, 19 ] ] }, { "plaintext": "An Oldham coupling has three discs, one coupled to the input, one coupled to the output, and a middle disc that is joined to the first two by tongue and groove. The tongue and groove on one side is perpendicular to the tongue and groove on the other. The middle disc rotates around its center at the same speed as the input and output shafts. Its center traces a circular orbit, twice per rotation, around the midpoint between input and output shafts. Often springs are used to reduce backlash of the mechanism. An advantage to this type of coupling, as compared to two universal joints, is its compact size. The coupler is named for John Oldham who invented it in Ireland, in 1821, to solve a problem in a paddle steamer design.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 197667, 316617, 10058792, 20407070, 147575, 334071 ], "anchor_spans": [ [ 142, 159 ], [ 460, 466 ], [ 487, 495 ], [ 636, 647 ], [ 667, 674 ], [ 709, 723 ] ] }, { "plaintext": "Rag joints are commonly used on automotive steering linkages and drive trains. When used on a drive train they are sometimes known as giubos.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 264373, 41620681, 25204631 ], "anchor_spans": [ [ 43, 51 ], [ 65, 76 ], [ 134, 139 ] ] }, { "plaintext": "Rigid couplings are used when precise shaft alignment is required; any shaft misalignment will affect the coupling's performance as well as its life span, because rigid couplings do not have the ability to compensate for misalignment. Due to this, their application is limited, and they're typically used in applications involving vertical drivers.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Clamped or compression rigid couplings come in two parts and fit together around the shafts to form a sleeve. They offer more flexibility than sleeved models, and can be used on shafts that are fixed in place. They generally are large enough so that screws can pass all the way through the coupling and into the second half to ensure a secure hold. Flanged rigid couplings are designed for heavy loads or industrial equipment. They consist of short sleeves surrounded by a perpendicular flange. One coupling is placed on each shaft so the two flanges line up face to face. A series of screws or bolts can then be installed in the flanges to hold them together. Because of their size and durability, flanged units can be used to bring shafts into alignment before they are joined.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A sleeve coupling consists of a pipe whose bore is finished to the required tolerance based on the shaft size. Based on the usage of the coupling a keyway is made in the bore in order to transmit the torque by means of the key. Two threaded holes are provided in order to lock the coupling in position.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 26719969, 3704228, 9386904, 18398883, 30400 ], "anchor_spans": [ [ 2, 17 ], [ 32, 36 ], [ 43, 47 ], [ 148, 154 ], [ 200, 206 ] ] }, { "plaintext": "Sleeve couplings are also known as box couplings. In this case shaft ends are coupled together and abutted against each other which are enveloped by muff or sleeve.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A gib head sunk keys hold the two shafts and sleeve together (this is the simplest type of the coupling) It is made from the cast iron and very simple to design and manufacture. It consists of a hollow pipe whose inner diameter is same as diameter of the shafts.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The hollow pipe is fitted over a two or more ends of the shafts with the help of the taper sunk key. A key and sleeve are useful to transmit power from one shaft to another shaft.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A tapered lock is a form of keyless shaft locking device that does not require any material to be removed from the shaft. The basic idea is similar to a clamp coupling but the moment of rotation is closer to the center of the shaft. An alternative Others to the traditional parallel key, the tapered lock removes the possibility of play due to worn keyways. It is more robust than using a key because maintenance only requires one tool and the self-centering balanced rotation means it lasts longer than a keyed joint would, but the downside is that it costs more.", "section_idx": 2, "section_name": "Types", "target_page_ids": [ 18398883, 18398883, 10058792 ], "anchor_spans": [ [ 28, 31 ], [ 274, 286 ], [ 332, 336 ] ] }, { "plaintext": "A flexible coupling made from two counter-wound springs with a ball bearing in the center, which allows torque transfer from input to output shaft. Requires no lubrication to consistently run as it has no internal components.", "section_idx": 2, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Coupling maintenance requires a regularly scheduled inspection of each coupling. It consists of:", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Performing visual inspections", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Checking for signs of wear or fatigue", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Cleaning couplings regularly", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Checking and changing lubricant regularly if the coupling is lubricated. This maintenance is required annually for most couplings and more frequently for couplings in adverse environments or in demanding operating conditions.", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Documenting the maintenance performed on each coupling, along with the date.", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Even with proper maintenance, however, couplings can fail. Underlying reasons for failure, other than maintenance, include:", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Improper installation", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Poor coupling selection", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Operation beyond design capabilities.", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "External signs that indicate potential coupling failure include:", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Abnormal noise, such as screeching, squealing or chattering", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Excessive vibration or wobble", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Failed seals indicated by lubricant leakage or contamination.", "section_idx": 3, "section_name": "Coupling maintenance and failure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Couplings are normally balanced at the factory prior to being shipped, but they occasionally go out of balance in operation. Balancing can be difficult and expensive, and is normally done only when operating tolerances are such that the effort and the expense are justified. The amount of coupling unbalance that can be tolerated by any system is dictated by the characteristics of the specific connected machines and can be determined by detailed analysis or experience.", "section_idx": 4, "section_name": "Checking the coupling balance", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Biography of Oldham at Cornell University", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Yutaka Nishiyama, From Oldham's Coupling to Air Conditioners", "section_idx": 6, "section_name": "External links", "target_page_ids": [ 36203384 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Couplings", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Rotating_shaft_couplings", "Mechanisms_(engineering)", "Hardware_(mechanical)" ]

[]

[ { "plaintext": "Cover or covers may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Another name for a lid", "section_idx": 1, "section_name": "Packaging", "target_page_ids": [ 2332073 ], "anchor_spans": [ [ 20, 23 ] ] }, { "plaintext": " Cover (philately), generic term for envelope or package", "section_idx": 1, "section_name": "Packaging", "target_page_ids": [ 487366 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Album cover, the front of the packaging", "section_idx": 1, "section_name": "Packaging", "target_page_ids": [ 1933002 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Book cover or magazine cover", "section_idx": 1, "section_name": "Packaging", "target_page_ids": [ 3723902 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Book design", "section_idx": 1, "section_name": "Packaging", "target_page_ids": [ 2803724 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Back cover copy, part of copywriting", "section_idx": 1, "section_name": "Packaging", "target_page_ids": [ 1728077, 1728077 ], "anchor_spans": [ [ 1, 16 ], [ 26, 37 ] ] }, { "plaintext": " CD and DVD cover, CD and DVD packaging", "section_idx": 1, "section_name": "Packaging", "target_page_ids": [ 632395 ], "anchor_spans": [ [ 19, 39 ] ] }, { "plaintext": " Smartphone cover, a mobile phone accessory that protects a mobile phone", "section_idx": 1, "section_name": "Packaging", "target_page_ids": [ 15758238 ], "anchor_spans": [ [ 21, 43 ] ] }, { "plaintext": " Cover (surname)", "section_idx": 2, "section_name": "People", "target_page_ids": [ 44924405 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": "Cover", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Cover (Tom Verlaine album), 1984", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 21805014 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Cover (Joan as Policewoman album), 2009", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 24524885 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": "Covered", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Covered (Cold Chisel album), 2011", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 49578114 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Covered (Macy Gray album), 2012", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 34415144 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Covered (Robert Glasper album), 2015", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 51077850 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": "Covers", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Covers (Beni album), 2012", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 34752088 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Covers (Regine Velasquez album), 2004", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 28706329 ], "anchor_spans": [ [ 1, 32 ] ] }, { "plaintext": " Covers (Placebo album), 2003", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 9978075 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Covers (Show of Hands album), 2000", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 2099797 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Covers (James Taylor album), 2008", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 18730633 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Covers (Fayray album), 2005", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 7979607 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Covers (Deftones album), 2011", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 31342667 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Covers, an album by Break of Reality", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 4735287 ], "anchor_spans": [ [ 21, 37 ] ] }, { "plaintext": " Covers (A Camp EP), 2009", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 24659921 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Covers (Franz Ferdinand EP), 2009", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 39624021 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Covers (Get Cape. Wear Cape. Fly EP), 2009", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 5918355 ], "anchor_spans": [ [ 1, 37 ] ] }, { "plaintext": " Covers (The Autumns EP), 2001", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 3894565 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Covers (Young Statues EP), 2012", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 43399978 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Cover version, a new version of a previously released song", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 159031 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Cover, an understudy in opera", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 365239 ], "anchor_spans": [ [ 11, 21 ] ] }, { "plaintext": " Cover (film), a 2007 film directed by Bill Duke", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 24402410 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Covers (film), an upcoming comedy film directed by Nisha Ganatra", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 60816462 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Cover Magazine (publication), a New York City arts monthly publication", "section_idx": 3, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 29804514 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Cover (finance), repurchasing a short order made on the stock/equity, forex or futures markets", "section_idx": 4, "section_name": "Business", "target_page_ids": [ 113519 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Cover (law), a remedy for the breach of a contract for the receipt of goods", "section_idx": 4, "section_name": "Business", "target_page_ids": [ 2065994 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Cover charge, an entry fee", "section_idx": 4, "section_name": "Business", "target_page_ids": [ 2598754 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Cover (hospitality)", "section_idx": 4, "section_name": "Business", "target_page_ids": [ 64286097 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Cover Corp., parent organization for VTuber idol company Hololive Production", "section_idx": 4, "section_name": "Business", "target_page_ids": [ 64496091 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Cover (telecommunications), a communications concealment technique", "section_idx": 5, "section_name": "Deception and concealment", "target_page_ids": [ 487354 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Cover, something fake used in a cover-up", "section_idx": 5, "section_name": "Deception and concealment", "target_page_ids": [ 158936 ], "anchor_spans": [ [ 33, 41 ] ] }, { "plaintext": " Non-official cover, the identity assumed by an operative who takes a covert role in an organization without official ties to the government", "section_idx": 5, "section_name": "Deception and concealment", "target_page_ids": [ 848358 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Official cover, the identity assumed by an operative who takes a position in an organization with diplomatic ties", "section_idx": 5, "section_name": "Deception and concealment", "target_page_ids": [ 3031347 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Cover (algebra), the concept of an algebraic structure that maps onto another structure in structure-preserving fashion", "section_idx": 6, "section_name": "Mathematics, science and technology", "target_page_ids": [ 23931341 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Cover (topology), the mathematical concept of a collection of sets whose union contains each set as a subset", "section_idx": 6, "section_name": "Mathematics, science and technology", "target_page_ids": [ 317552 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Cover, a pair in the covering relation of a partially ordered set, or the greater element in such a pair", "section_idx": 6, "section_name": "Mathematics, science and technology", "target_page_ids": [ 14835049 ], "anchor_spans": [ [ 22, 39 ] ] }, { "plaintext": " Cover, in database theory, an equivalent set of constraints", "section_idx": 6, "section_name": "Mathematics, science and technology", "target_page_ids": [ 25873 ], "anchor_spans": [ [ 49, 60 ] ] }, { "plaintext": " Land cover, physical material on the surface of the earth", "section_idx": 6, "section_name": "Mathematics, science and technology", "target_page_ids": [ 6974596 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Concrete cover, in engineering, distance between reinforcement and the outer surface of element", "section_idx": 6, "section_name": "Mathematics, science and technology", "target_page_ids": [ 6448117 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Sedimentary cover, in geology, overlies a basement or crystalline basement", "section_idx": 6, "section_name": "Mathematics, science and technology", "target_page_ids": [ 5417918 ], "anchor_spans": [ [ 43, 51 ] ] }, { "plaintext": " Protection from enemy fire - see, for example, infantry tactics", "section_idx": 7, "section_name": "Military", "target_page_ids": [ 2909541 ], "anchor_spans": [ [ 48, 64 ] ] }, { "plaintext": " Cover or covering fire, also known as suppressive fire", "section_idx": 7, "section_name": "Military", "target_page_ids": [ 652110 ], "anchor_spans": [ [ 39, 55 ] ] }, { "plaintext": " A term for any type of uniform hat:", "section_idx": 7, "section_name": "Military", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Campaign cover or campaign hat, a broad-brimmed felt or straw hat", "section_idx": 7, "section_name": "Military", "target_page_ids": [ 1778166 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Utility cover, the United States Marine Corps cap", "section_idx": 7, "section_name": "Military", "target_page_ids": [ 14621753 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Cover (cricket), a region of the field with respect to the batsman in cricket", "section_idx": 8, "section_name": "Sports", "target_page_ids": [ 54152487 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " To cover, a term in sports betting regarding a game's point spread", "section_idx": 8, "section_name": "Sports", "target_page_ids": [ 52900 ], "anchor_spans": [ [ 55, 67 ] ] }, { "plaintext": " Cover letter, a letter of introduction accompanying another document", "section_idx": 9, "section_name": "Other uses", "target_page_ids": [ 10366024 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Cover, or covers, the top layer of bedding", "section_idx": 9, "section_name": "Other uses", "target_page_ids": [ 892720 ], "anchor_spans": [ [ 36, 43 ] ] }, { "plaintext": " Slipcover, protection for a piece of upholstered furniture", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 664494 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Coverage (disambiguation)", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 527005 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Covering (disambiguation)", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 377742 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Uncover (disambiguation)", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 13830121 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Uncovered (disambiguation)", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 13452697 ], "anchor_spans": [ [ 1, 27 ] ] } ]

[]

[ "Cover", "Covers" ]

[ { "plaintext": "Critical angle may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Critical angle (optics), the angle of incidence above which total internal reflection occurs", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 30426 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Critical angle of attack, in aerodynamics; the angle of attack which produces the maximum lift coefficient", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 232102 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Critical angle of repose, in engineering; the steepest angle of descent of a slope when the material is on the verge of sliding", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 518397 ], "anchor_spans": [ [ 0, 24 ] ] } ]

[]

[]

[ { "plaintext": "In telecommunication, the term critical frequency has the following meanings:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " In radio propagation by way of the ionosphere, the limiting frequency at or below which a wave component is reflected by, and above which it penetrates through, an ionospheric layer.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 271195, 15097, 495387, 10779 ], "anchor_spans": [ [ 4, 21 ], [ 36, 46 ], [ 52, 60 ], [ 61, 70 ] ] }, { "plaintext": " At near vertical incidence, the limiting frequency at or below which incidence, the wave component is reflected by, and above which it penetrates through, an ionospheric layer.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Critical Frequency changes with time of day, atmospheric conditions and angle of fire of the radio waves by antenna.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The existence of the critical frequency is the result of electron limitation, i.e., the inadequacy of the existing number of free electrons to support reflection at higher frequencies.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42728 ], "anchor_spans": [ [ 151, 161 ] ] }, { "plaintext": "In signal processing the critical frequency it is also another name for the Nyquist frequency.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 29324, 164685 ], "anchor_spans": [ [ 3, 20 ], [ 76, 93 ] ] }, { "plaintext": "Critical frequency is the highest magnitude of frequency above which the waves penetrate the ionosphere and below which the waves are reflected back from the ionosphere.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "It is denoted by \"fc\".", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Its value is not fixed and it depends upon the electron density of the ionosphere.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Critical frequency can be computed with the electron density given by:", "section_idx": 1, "section_name": "Equations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where Nmax is maximum electron density per m3 and fc is in Hz.", "section_idx": 1, "section_name": "Equations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Critical frequency can be computed by:", "section_idx": 1, "section_name": "Equations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where MUF is maximum usable frequency and is the angle of incidence", "section_idx": 1, "section_name": "Equations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The dependence of critical frequency with respect with electron density can be related through plasma oscillation concept particularly the 'Cold' Electrons mechanism.", "section_idx": 2, "section_name": "Relationship with Plasma Frequency", "target_page_ids": [ 900733, 900733 ], "anchor_spans": [ [ 95, 113 ], [ 139, 155 ] ] }, { "plaintext": "Using the electron charge , electron mass and permittivity of free space gives,", "section_idx": 2, "section_name": "Relationship with Plasma Frequency", "target_page_ids": [ 174945, 21144218, 2582879 ], "anchor_spans": [ [ 10, 25 ], [ 28, 41 ], [ 47, 73 ] ] }, { "plaintext": "and solving for the frequency,", "section_idx": 2, "section_name": "Relationship with Plasma Frequency", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The index of refraction has the formula which shows dependence in wavelength. The result that the force due to the polarization field in an ionized gas of low concentration is canceled by the effect of collisions between ions and electrons is re‐established in a simple manner that clearly displays the physical basis for the effect. Because of this cancellation the Sellmeyer formula, determines the relation between the electron number density, N, and the index of refraction, n, in the ionosphere when collisions are neglected.", "section_idx": 3, "section_name": "Relationship with Index of Refraction", "target_page_ids": [ 25880, 33125, 161306 ], "anchor_spans": [ [ 4, 23 ], [ 66, 76 ], [ 367, 384 ] ] }, { "plaintext": ".", "section_idx": 3, "section_name": "Relationship with Index of Refraction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Using the default values for electron charge , permittivity of free space and electron mass , and changing angular velocity with respect to frequency this yields to", "section_idx": 3, "section_name": "Relationship with Index of Refraction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "and solving for the refraction index n,", "section_idx": 3, "section_name": "Relationship with Index of Refraction", "target_page_ids": [ 25880 ], "anchor_spans": [ [ 20, 36 ] ] }, { "plaintext": " All long-distance HF Radio Communications use HF Radio signals that are obliquely incident on the ionosphere, If the HF frequency is above Critical Frequency, the radio signals are passing through the ionosphere at an angle instead of head-on.", "section_idx": 4, "section_name": "Critical Frequency and F layer of the Ionosphere", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The Critical Frequency is changing continuously and the F layer of the Ionosphere is mostly responsible for the reflection of radio waves back to Earth,", "section_idx": 4, "section_name": "Critical Frequency and F layer of the Ionosphere", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The other layers(D) interact in other ways - absorption of frequency and during the day, the D Layers forms, and the F layer splits into F1 and F2 layers.", "section_idx": 4, "section_name": "Critical Frequency and F layer of the Ionosphere", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Because of changing the Ionosphere during day and night, during daytime higher frequency bands under critical Frequency work best, but during nighttime the lower frequency bands work best.", "section_idx": 4, "section_name": "Critical Frequency and F layer of the Ionosphere", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The D layer is present during the day and it is a good absorber of radio waves, increasing losses, Higher frequencies are absorbed less, so higher frequencies tends to perform better during daytime.", "section_idx": 4, "section_name": "Critical Frequency and F layer of the Ionosphere", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The actual F2-Layer Critical Frequency Map link which refreshes every five minutes can be seen in this website ", "section_idx": 4, "section_name": "Critical Frequency and F layer of the Ionosphere", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The Ionosphere and the Practical Maximum Usable Frequencies (MUFs) Map link which refreshes every five minutes can be seen in this website ", "section_idx": 4, "section_name": "Critical Frequency and F layer of the Ionosphere", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " High Frequency", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 178937 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " High Frequency Active Auroral Research Program", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 73615 ], "anchor_spans": [ [ 1, 47 ] ] }, { "plaintext": " High Frequency Internet Protocol", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 11296576 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Low frequency", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 160518 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Radio propagation", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 271195 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Space weather", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 113496 ], "anchor_spans": [ [ 1, 14 ] ] } ]

[ "Telecommunication_theory" ]

[]

[ { "plaintext": "Crosstalk refers to any signal or circuit unintentionally affecting another signal or circuit.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2995499 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Crosstalk may also refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Crosstalk (biology)", "section_idx": 1, "section_name": "Science and computing", "target_page_ids": [ 2995501 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Crosstalk Mk.4, a communications application for PCs.", "section_idx": 1, "section_name": "Science and computing", "target_page_ids": [ 20792659 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Cross talk, a style of comedy used in performance by double acts", "section_idx": 2, "section_name": "Arts and entertainment", "target_page_ids": [ 817445 ], "anchor_spans": [ [ 54, 65 ] ] }, { "plaintext": " Xiangsheng, also translated as \"crosstalk\", a traditional Chinese comedic monologue or dialogue", "section_idx": 2, "section_name": "Arts and entertainment", "target_page_ids": [ 1131404 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Crosstalk (novel), a 2016 novel by American science fiction author Connie Willis", "section_idx": 2, "section_name": "Arts and entertainment", "target_page_ids": [ 57640484 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Crosstalk (film), a 1982 science fiction thriller film", "section_idx": 2, "section_name": "Arts and entertainment", "target_page_ids": [ 26970731 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Cross Talk, a 1980 album by the Pretty Things", "section_idx": 2, "section_name": "Arts and entertainment", "target_page_ids": [ 10882335 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " American Speech Music, a compilation album by the produced by Mendi + Keith Obadike", "section_idx": 2, "section_name": "Arts and entertainment", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " CrossTalk (TV series), a television program on the Russian-based international broadcaster RT", "section_idx": 2, "section_name": "Arts and entertainment", "target_page_ids": [ 34072681 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Cross Talk, a defunct radio show hosted by Indian RJ Balaji", "section_idx": 2, "section_name": "Arts and entertainment", "target_page_ids": [ 32908796 ], "anchor_spans": [ [ 51, 60 ] ] } ]

[]

[]

[ { "plaintext": "In telecommunication, a cryptochannel is a complete system of crypto-communications between two or more holders. It includes: (a) the cryptographic aids prescribed; (b) the holders thereof; (c) the indicators or other means of identification; (d) the area or areas in which effective; (e) the special purpose, if any, for which provided; and (f) pertinent notes as to distribution, usage, etc. A cryptochannel is analogous to a radio circuit.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 8286675, 18934432, 15368428, 346001 ], "anchor_spans": [ [ 3, 20 ], [ 52, 58 ], [ 62, 83 ], [ 428, 433 ], [ 434, 441 ] ] }, { "plaintext": "Cryptosystem", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 506383 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Secure channel", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 592935 ], "anchor_spans": [ [ 0, 14 ] ] } ]

[ "Cryptography", "Military_communications" ]

[]

[ { "plaintext": "A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is a quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators. However, other piezoelectricity materials including polycrystalline ceramics are used in similar circuits.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9920, 9559, 24975, 6015, 43540545, 21304320, 182693, 8276, 15150, 61164, 491851, 25233, 365435 ], "anchor_spans": [ [ 27, 48 ], [ 49, 56 ], [ 69, 82 ], [ 83, 90 ], [ 96, 123 ], [ 194, 213 ], [ 235, 247 ], [ 252, 259 ], [ 260, 278 ], [ 314, 331 ], [ 337, 345 ], [ 406, 412 ], [ 553, 568 ] ] }, { "plaintext": "A crystal oscillator relies on the slight change in shape of a quartz crystal under an electric field, a property known as electrostriction or inverse piezoelectricity. A voltage applied to the electrodes on the crystal causes it to change shape; when the voltage is removed, the crystal generates a small voltage as it elastically returns to its original shape. The quartz oscillates at a stable resonant frequency, behaving like an RLC circuit, but with a much higher Q factor (less energy loss on each cycle of oscillation). Once a quartz crystal is adjusted to a particular frequency (which is affected by the mass of electrodes attached to the crystal, the orientation of the crystal, temperature and other factors), it maintains that frequency with high stability.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41092, 1303480, 10008, 27174683, 229160 ], "anchor_spans": [ [ 87, 101 ], [ 123, 139 ], [ 194, 203 ], [ 434, 445 ], [ 470, 478 ] ] }, { "plaintext": "Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz. As of 2003, around two billion crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. However in applications where small size and weight is needed crystals can be replaced by thin-film bulk acoustic resonators, specifically if high frequency (more than roughly 1.5GHz) resonance is needed. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 14121, 60883, 6449, 15368428, 7878457, 19644137, 4166537, 41927, 15361791 ], "anchor_spans": [ [ 68, 77 ], [ 214, 224 ], [ 228, 233 ], [ 236, 241 ], [ 244, 252 ], [ 259, 268 ], [ 361, 394 ], [ 564, 580 ], [ 587, 599 ] ] }, { "plaintext": "A crystal oscillator is an electric oscillator type circuit that uses a piezoelectric resonator, a crystal, as its frequency-determining element. Crystal is the common term used in electronics for the frequency-determining component, a wafer of quartz crystal or ceramic with electrodes connected to it. A more accurate term for it is piezoelectric resonator. Crystals are also used in other types of electronic circuits, such as crystal filters.", "section_idx": 1, "section_name": "Terminology", "target_page_ids": [ 22522, 25233, 234088 ], "anchor_spans": [ [ 27, 46 ], [ 246, 260 ], [ 432, 446 ] ] }, { "plaintext": "Piezoelectric resonators are sold as separate components for use in crystal oscillator circuits. An example is shown in the picture. They are also often incorporated in a single package with the crystal oscillator circuit, shown on the righthand side.", "section_idx": 1, "section_name": "Terminology", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Piezoelectricity was discovered by Jacques and Pierre Curie in 1880. Paul Langevin first investigated quartz resonators for use in sonar during World War I. The first crystal-controlled oscillator, using a crystal of Rochelle salt, was built in 1917 and patented in 1918 by Alexander M. Nicholson at Bell Telephone Laboratories, although his priority was disputed by Walter Guyton Cady. Cady built the first quartz crystal oscillator in 1921.", "section_idx": 2, "section_name": "History", "target_page_ids": [ 24975, 54959893, 24509, 681413, 29438, 9920, 357565, 49007100, 3712, 14176294 ], "anchor_spans": [ [ 0, 16 ], [ 35, 42 ], [ 47, 59 ], [ 69, 82 ], [ 131, 136 ], [ 186, 196 ], [ 217, 230 ], [ 274, 296 ], [ 300, 327 ], [ 367, 385 ] ] }, { "plaintext": "Other early innovators in quartz crystal oscillators include G. W. Pierce and Louis Essen.", "section_idx": 2, "section_name": "History", "target_page_ids": [ 10569035, 495065 ], "anchor_spans": [ [ 61, 73 ], [ 78, 89 ] ] }, { "plaintext": "Quartz crystal oscillators were developed for high-stability frequency references during the 1920s and 1930s. Prior to crystals, radio stations controlled their frequency with tuned circuits, which could easily drift off frequency by 3–4kHz. Since broadcast stations were assigned frequencies only 10kHz (Americas) or 9kHz (elsewhere) apart, interference between adjacent stations due to frequency drift was a common problem. In 1925, Westinghouse installed a crystal oscillator in its flagship station KDKA, and by 1926, quartz crystals were used to control the frequency of many broadcasting stations and were popular with amateur radio operators. In 1928, Warren Marrison of Bell Telephone Laboratories developed the first quartz-crystal clock. With accuracies of up to 1 second in 30 years (30ms/y, or 0.95ns/s), quartz clocks replaced precision pendulum clocks as the world's most accurate timekeepers until atomic clocks were developed in the 1950s. Using the early work at Bell Labs, AT&T eventually established their Frequency Control Products division, later spun off and known today as Vectron International.", "section_idx": 2, "section_name": "History", "target_page_ids": [ 602264, 21304320, 24989, 25453985 ], "anchor_spans": [ [ 177, 190 ], [ 728, 748 ], [ 853, 867 ], [ 916, 928 ] ] }, { "plaintext": "A number of firms started producing quartz crystals for electronic use during this time. Using what are now considered primitive methods, about 100,000 crystal units were produced in the United States during 1939. Through World War II crystals were made from natural quartz crystal, virtually all from Brazil. Shortages of crystals during the war caused by the demand for accurate frequency control of military and naval radios and radars spurred postwar research into culturing synthetic quartz, and by 1950 a hydrothermal process for growing quartz crystals on a commercial scale was developed at Bell Laboratories. By the 1970s virtually all crystals used in electronics were synthetic.", "section_idx": 2, "section_name": "History", "target_page_ids": [ 32927, 3383, 15368428, 25676, 7987481, 3712 ], "anchor_spans": [ [ 226, 238 ], [ 306, 312 ], [ 426, 431 ], [ 437, 442 ], [ 516, 528 ], [ 604, 621 ] ] }, { "plaintext": "In 1968, Juergen Staudte invented a photolithographic process for manufacturing quartz crystal oscillators while working at North American Aviation (now Rockwell) that allowed them to be made small enough for portable products like watches.", "section_idx": 2, "section_name": "History", "target_page_ids": [ 23748, 221761, 26367 ], "anchor_spans": [ [ 36, 53 ], [ 124, 147 ], [ 153, 161 ] ] }, { "plaintext": "Although crystal oscillators still most commonly use quartz crystals, devices using other materials are becoming more common, such as ceramic resonators.", "section_idx": 2, "section_name": "History", "target_page_ids": [ 6102991 ], "anchor_spans": [ [ 134, 151 ] ] }, { "plaintext": "A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions.", "section_idx": 3, "section_name": "Operation", "target_page_ids": [ 6015, 18993816, 902, 19555, 18963787 ], "anchor_spans": [ [ 2, 9 ], [ 15, 20 ], [ 46, 50 ], [ 53, 61 ], [ 67, 70 ] ] }, { "plaintext": "Almost any object made of an elastic material could be used like a crystal, with appropriate transducers, since all objects have natural resonant frequencies of vibration. For example, steel is very elastic and has a high speed of sound. It was often used in mechanical filters before quartz. The resonant frequency depends on size, shape, elasticity, and the speed of sound in the material. High-frequency crystals are typically cut in the shape of a simple rectangle or circular disk. Low-frequency crystals, such as those used in digital watches, are typically cut in the shape of a tuning fork. For applications not needing very precise timing, a low-cost ceramic resonator is often used in place of a quartz crystal.", "section_idx": 3, "section_name": "Operation", "target_page_ids": [ 268923, 242666, 41660, 20646772, 27058, 25154546, 268923, 147853, 31198, 6102991 ], "anchor_spans": [ [ 29, 36 ], [ 93, 103 ], [ 137, 145 ], [ 161, 170 ], [ 185, 190 ], [ 259, 276 ], [ 340, 350 ], [ 360, 374 ], [ 586, 597 ], [ 660, 677 ] ] }, { "plaintext": "When a crystal of quartz is properly cut and mounted, it can be made to distort in an electric field by applying a voltage to an electrode near or on the crystal. This property is known as electrostriction or inverse piezoelectricity. When the field is removed, the quartz generates an electric field as it returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal behaves like an RLC circuit, composed of an inductor, capacitor and resistor, with a precise resonant frequency.", "section_idx": 3, "section_name": "Operation", "target_page_ids": [ 25233, 41092, 32549, 10008, 1303480, 27174683, 14896, 4932111, 25754 ], "anchor_spans": [ [ 18, 24 ], [ 86, 100 ], [ 115, 122 ], [ 129, 138 ], [ 189, 205 ], [ 423, 434 ], [ 451, 459 ], [ 461, 470 ], [ 475, 483 ] ] }, { "plaintext": "Quartz has the further advantage that its elastic constants and its size change in such a way that the frequency dependence on temperature can be very low. The specific characteristics depend on the mode of vibration and the angle at which the quartz is cut (relative to its crystallographic axes). Therefore, the resonant frequency of the plate, which depends on its size, does not change much. This means that a quartz clock, filter or oscillator remains accurate. For critical applications the quartz oscillator is mounted in a temperature-controlled container, called a crystal oven, and can also be mounted on shock absorbers to prevent perturbation by external mechanical vibrations.", "section_idx": 3, "section_name": "Operation", "target_page_ids": [ 2602534 ], "anchor_spans": [ [ 574, 586 ] ] }, { "plaintext": "A quartz crystal can be modeled as an electrical network with low-impedance (series) and high-impedance (parallel) resonance points spaced closely together. Mathematically (using the Laplace transform), the impedance of this network can be written as:", "section_idx": 4, "section_name": "Modeling", "target_page_ids": [ 41957, 41957, 18610 ], "anchor_spans": [ [ 66, 75 ], [ 94, 103 ], [ 183, 200 ] ] }, { "plaintext": "or", "section_idx": 4, "section_name": "Modeling", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where is the complex frequency (), is the series resonant angular frequency, and is the parallel resonant angular frequency.", "section_idx": 4, "section_name": "Modeling", "target_page_ids": [ 199829 ], "anchor_spans": [ [ 60, 77 ] ] }, { "plaintext": "Adding capacitance across a crystal causes the (parallel) resonant frequency to decrease. Adding inductance across a crystal causes the (parallel) resonant frequency to increase. These effects can be used to adjust the frequency at which a crystal oscillates. Crystal manufacturers normally cut and trim their crystals to have a specified resonant frequency with a known \"load\" capacitance added to the crystal. For example, a crystal intended for a 6pF load has its specified parallel resonant frequency when a 6.0pF capacitor is placed across it. Without the load capacitance, the resonant frequency is higher.", "section_idx": 4, "section_name": "Modeling", "target_page_ids": [ 140711, 165146 ], "anchor_spans": [ [ 7, 18 ], [ 97, 107 ] ] }, { "plaintext": "A quartz crystal provides both series and parallel resonance. The series resonance is a few kilohertz lower than the parallel one. Crystals below 30MHz are generally operated between series and parallel resonance, which means that the crystal appears as an inductive reactance in operation, this inductance forming a parallel resonant circuit with externally connected parallel capacitance. Any small additional capacitance in parallel with the crystal pulls the frequency lower. Moreover, the effective inductive reactance of the crystal can be reduced by adding a capacitor in series with the crystal. This latter technique can provide a useful method of trimming the oscillatory frequency within a narrow range; in this case inserting a capacitor in series with the crystal raises the frequency of oscillation. For a crystal to operate at its specified frequency, the electronic circuit has to be exactly that specified by the crystal manufacturer. Note that these points imply a subtlety concerning crystal oscillators in this frequency range: the crystal does not usually oscillate at precisely either of its resonant frequencies.", "section_idx": 4, "section_name": "Modeling", "target_page_ids": [ 140710 ], "anchor_spans": [ [ 257, 276 ] ] }, { "plaintext": "Crystals above 30MHz (up to >200MHz) are generally operated at series resonance where the impedance appears at its minimum and equal to the series resistance. For these crystals the series resistance is specified (<100Ω) instead of the parallel capacitance. To reach higher frequencies, a crystal can be made to vibrate at one of its overtone modes, which occur near multiples of the fundamental resonant frequency. Only odd numbered overtones are used. Such a crystal is referred to as a 3rd, 5th, or even 7th overtone crystal. To accomplish this, the oscillator circuit usually includes additional LC circuits to select the desired overtone.", "section_idx": 4, "section_name": "Modeling", "target_page_ids": [ 41480, 602264 ], "anchor_spans": [ [ 334, 342 ], [ 600, 610 ] ] }, { "plaintext": "A crystal's frequency characteristic depends on the shape or \"cut\" of the crystal. A tuning-fork crystal is usually cut such that its frequency dependence on temperature is quadratic with the maximum around 25°C. This means that a tuning-fork crystal oscillator resonates close to its target frequency at room temperature, but slows when the temperature either increases or decreases from room temperature. A common parabolic coefficient for a 32kHz tuning-fork crystal is −0.04 ppm/°C2:", "section_idx": 4, "section_name": "Modeling", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In a real application, this means that a clock built using a regular 32kHz tuning-fork crystal keeps good time at room temperature, but loses 2 minutes per year at 10°C above or below room temperature and loses 8 minutes per year at 20°C above or below room temperature due to the quartz crystal.", "section_idx": 4, "section_name": "Modeling", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The crystal oscillator circuit sustains oscillation by taking a voltage signal from the quartz resonator, amplifying it, and feeding it back to the resonator. The rate of expansion and contraction of the quartz is the resonant frequency, and is determined by the cut and size of the crystal. When the energy of the generated output frequencies matches the losses in the circuit, an oscillation can be sustained.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [ 521510, 41660 ], "anchor_spans": [ [ 95, 104 ], [ 218, 226 ] ] }, { "plaintext": "An oscillator crystal has two electrically conductive plates, with a slice or tuning fork of quartz crystal sandwiched between them. During startup, the controlling circuit places the crystal into an unstable equilibrium, and due to the positive feedback in the system, any tiny fraction of noise is amplified, ramping up the oscillation. The crystal resonator can also be seen as a highly frequency-selective filter in this system: it only passes a very narrow subband of frequencies around the resonant one, attenuating everything else. Eventually, only the resonant frequency is active. As the oscillator amplifies the signals coming out of the crystal, the signals in the crystal's frequency band becomes stronger, eventually dominating the output of the oscillator. The narrow resonance band of the quartz crystal filters out all the unwanted frequencies.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [ 3652079, 213354, 3966982, 1866533 ], "anchor_spans": [ [ 200, 220 ], [ 237, 254 ], [ 291, 296 ], [ 819, 825 ] ] }, { "plaintext": "The output frequency of a quartz oscillator can be either that of the fundamental resonance or of a multiple of that resonance, called a harmonic frequency. Harmonics are an exact integer multiple of the fundamental frequency. But, like many other mechanical resonators, crystals exhibit several modes of oscillation, usually at approximately odd integer multiples of the fundamental frequency. These are termed \"overtone modes\", and oscillator circuits can be designed to excite them. The overtone modes are at frequencies which are approximate, but not exact odd integer multiples of that of the fundamental mode, and overtone frequencies are therefore not exact harmonics of the fundamental.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [ 41232 ], "anchor_spans": [ [ 137, 145 ] ] }, { "plaintext": "High frequency crystals are often designed to operate at third, fifth, or seventh overtones. Manufacturers have difficulty producing crystals thin enough to produce fundamental frequencies over 30MHz. To produce higher frequencies, manufacturers make overtone crystals tuned to put the 3rd, 5th, or 7th overtone at the desired frequency, because they are thicker and therefore easier to manufacture than a fundamental crystal that would produce the same frequency—although exciting the desired overtone frequency requires a slightly more complicated oscillator circuit.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A fundamental crystal oscillator circuit is simpler and more efficient and has more pullability than a third overtone circuit.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Depending on the manufacturer, the highest available fundamental frequency may be 25MHz to 66MHz.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A major reason for the wide use of crystal oscillators is their high Q factor. A typical Q value for a quartz oscillator ranges from 104 to 106, compared to perhaps 102 for an LC oscillator. The maximum Q for a high stability quartz oscillator can be estimated as Q = 1.6 107/f, where f is the resonant frequency in megahertz.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [ 229160, 9920 ], "anchor_spans": [ [ 69, 77 ], [ 176, 189 ] ] }, { "plaintext": "One of the most important traits of quartz crystal oscillators is that they can exhibit very low phase noise.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [ 41549 ], "anchor_spans": [ [ 97, 108 ] ] }, { "plaintext": "In many oscillators, any spectral energy at the resonant frequency is amplified by the oscillator, resulting in a collection of tones at different phases.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In a crystal oscillator, the crystal mostly vibrates in one axis, therefore only one phase is dominant.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This property of low phase noise makes them particularly useful in telecommunications where stable signals are needed, and in scientific equipment where very precise time references are needed.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [ 41549 ], "anchor_spans": [ [ 21, 32 ] ] }, { "plaintext": "Environmental changes of temperature, humidity, pressure, and vibration can change the resonant frequency of a quartz crystal, but there are several designs that reduce these environmental effects. These include the TCXO, MCXO, and OCXO which are defined Circuit_notations_and_abbreviations. These designs, particularly the OCXO, often produce devices with excellent short-term stability. The limitations in short-term stability are due mainly to noise from electronic components in the oscillator circuits. Long-term stability is limited by aging of the crystal.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [ 2602534 ], "anchor_spans": [ [ 232, 236 ] ] }, { "plaintext": "Due to aging and environmental factors (such as temperature and vibration), it is difficult to keep even the best quartz oscillators within one part in 1010 of their nominal frequency without constant adjustment. For this reason, atomic oscillators are used for applications requiring better long-term stability and accuracy.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [ 25453985 ], "anchor_spans": [ [ 230, 247 ] ] }, { "plaintext": "For crystals operated at series resonance or pulled away from the main mode by the inclusion of a series inductor or capacitor, significant (and temperature-dependent) spurious responses may be experienced. Though most spurious modes are typically some tens of kilohertz above the wanted series resonance their temperature coefficient is different from the main mode and the spurious response may move through the main mode at certain temperatures. Even if the series resistances at the spurious resonances appear higher than the one at wanted frequency a rapid change in the main mode series resistance can occur at specific temperatures when the two frequencies are coincidental.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A consequence of these activity dips is that the oscillator may lock at a spurious frequency at specific temperatures. This is generally minimized by ensuring that the maintaining circuit has insufficient gain to activate unwanted modes.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Spurious frequencies are also generated by subjecting the crystal to vibration. This modulates the resonant frequency to a small degree by the frequency of the vibrations. SC-cut crystals are designed to minimize the frequency effect of mounting stress and they are therefore less sensitive to vibration. Acceleration effects including gravity are also reduced with SC-cut crystals as is frequency change with time due to long term mounting stress variation.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "There are disadvantages with SC-cut shear mode crystals, such as the need for the maintaining oscillator to discriminate against other closely related unwanted modes and increased frequency change due to temperature when subject to a full ambient range. SC-cut crystals are most advantageous where temperature control at their temperature of zero temperature coefficient (turnover) is possible, under these circumstances an overall stability performance from premium units can approach the stability of Rubidium frequency standards.", "section_idx": 5, "section_name": "Crystal oscillator circuits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Crystals can be manufactured for oscillation over a wide range of frequencies, from a few kilohertz up to several hundred megahertz. Many applications call for a crystal oscillator frequency conveniently related to some other desired frequency, so hundreds of standard crystal frequencies are made in large quantities and stocked by electronics distributors. For example 3.579545MHz crystals, which are made in large quantities for NTSC color television receivers, are popular for many non-television applications uses too. Using frequency dividers, frequency multipliers and phase-locked loop circuits, it is practical to derive a wide range of frequencies from one reference frequency.", "section_idx": 6, "section_name": "Commonly used crystal frequencies", "target_page_ids": [ 21689, 29831, 5767604, 1199421, 41548 ], "anchor_spans": [ [ 432, 436 ], [ 443, 453 ], [ 530, 547 ], [ 550, 570 ], [ 576, 593 ] ] }, { "plaintext": "The most common material for oscillator crystals is quartz. At the beginning of the technology, natural quartz crystals were used but now synthetic crystalline quartz grown by hydrothermal synthesis is predominant due to higher purity, lower cost and more convenient handling. One of the few remaining uses of natural crystals is for pressure transducers in deep wells. During World War II and for some time afterwards, natural quartz was considered a strategic material by the USA. Large crystals were imported from Brazil. Raw \"lascas\", the source material quartz for hydrothermal synthesis, are imported to USA or mined locally by Coleman Quartz. The average value of as-grown synthetic quartz in 1994 was ", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 25233, 7987481, 32927, 41641569 ], "anchor_spans": [ [ 52, 58 ], [ 176, 198 ], [ 377, 389 ], [ 452, 470 ] ] }, { "plaintext": "Two types of quartz crystals exist: left-handed and right-handed. The two differ in their optical rotation but they are identical in other physical properties. Both left and right-handed crystals can be used for oscillators, if the cut angle is correct. In manufacture, right-handed quartz is generally used. The SiO4 tetrahedrons form parallel helices; the direction of twist of the helix determines the left- or right-hand orientation. The helixes are aligned along the z-axis and merged, sharing atoms. The mass of the helixes forms a mesh of small and large channels parallel to the z-axis. The large ones are large enough to allow some mobility of smaller ions and molecules through the crystal.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 39774 ], "anchor_spans": [ [ 90, 106 ] ] }, { "plaintext": "Quartz exists in several phases. At 573°C at 1 atmosphere (and at higher temperatures and higher pressures) the α-quartz undergoes quartz inversion, transforms reversibly to β-quartz. The reverse process however is not entirely homogeneous and crystal twinning occurs. Care must be taken during manufacturing and processing to avoid phase transformation. Other phases, e.g. the higher-temperature phases tridymite and cristobalite, are not significant for oscillators. All quartz oscillator crystals are the α-quartz type.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 15369863, 1997989, 1089354, 550450 ], "anchor_spans": [ [ 131, 147 ], [ 244, 260 ], [ 404, 413 ], [ 418, 430 ] ] }, { "plaintext": "Infrared spectrophotometry is used as one of the methods for measuring the quality of the grown crystals. The wavenumbers 3585, 3500, and 3410cm−1 are commonly used. The measured value is based on the absorption bands of the OH radical and the infrared Q value is calculated. The electronic grade crystals, grade C, have Q of 1.8 million or above; the premium grade B crystals have Q of 2.2 million, and special premium grade A crystals have Q of 3.0 million. The Q value is calculated only for the z region; crystals containing other regions can be adversely affected. Another quality indicator is the etch channel density; when the crystal is etched, tubular channels are created along linear defects. For processing involving etching, e.g. the wristwatch tuning fork crystals, low etch channel density is desirable. The etch channel density for swept quartz is about 10–100 and significantly more for unswept quartz. Presence of etch channels and etch pits degrades the resonator's Q and introduces nonlinearities.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 15412, 164570, 1551135, 737798, 42526 ], "anchor_spans": [ [ 0, 26 ], [ 110, 120 ], [ 201, 216 ], [ 225, 235 ], [ 645, 651 ] ] }, { "plaintext": "Quartz crystals can be grown for specific purposes.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Crystals for AT-cut are the most common in mass production of oscillator materials; the shape and dimensions are optimized for high yield of the required wafers. High-purity quartz crystals are grown with especially low content of aluminium, alkali metal and other impurities and minimal defects; the low amount of alkali metals provides increased resistance to ionizing radiation. Crystals for wrist watches, for cutting the tuning fork 32768Hz crystals, are grown with very low etch channel density.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 40979, 41860 ], "anchor_spans": [ [ 13, 19 ], [ 154, 160 ] ] }, { "plaintext": "Crystals for SAW devices are grown as flat, with large X-size seed with low etch channel density.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 459844 ], "anchor_spans": [ [ 13, 16 ] ] }, { "plaintext": "Special high-Q crystals, for use in highly stable oscillators, are grown at constant slow speed and have constant low infrared absorption along the entire Z axis. Crystals can be grown as Y-bar, with a seed crystal in bar shape and elongated along the Y axis, or as Z-plate, grown from a plate seed with Y-axis direction length and X-axis width. The region around the seed crystal contains a large number of crystal defects and should not be used for the wafers", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 1159186 ], "anchor_spans": [ [ 202, 214 ] ] }, { "plaintext": "Crystals grow anisotropically; the growth along the Z axis is up to 3 times faster than along the X axis. The growth direction and rate also influences the rate of uptake of impurities. Y-bar crystals, or Z-plate crystals with long Y axis, have four growth regions usually called +X, −X, Z, and S. The distribution of impurities during growth is uneven; different growth areas contain different levels of contaminants. The Z regions are the purest, the small occasionally present S regions are less pure, the +X region is yet less pure, and the -X region has the highest level of impurities. The impurities have a negative impact on radiation hardness, susceptibility to twinning, filter loss, and long and short term stability of the crystals. Different-cut seeds in different orientations may provide other kinds of growth regions. The growth speed of the −X direction is slowest due to the effect of adsorption of water molecules on the crystal surface; aluminium impurities suppress growth in two other directions. The content of aluminium is lowest in Z region, higher in +X, yet higher in −X, and highest in S; the size of S regions also grows with increased amount of aluminium present. The content of hydrogen is lowest in Z region, higher in +X region, yet higher in S region, and highest in −X. Aluminium inclusions transform into color centers with gamma-ray irradiation, causing a darkening of the crystal proportional to the dose and level of impurities; the presence of regions with different darkness reveals the different growth regions.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 1264, 1041641, 1997989 ], "anchor_spans": [ [ 14, 29 ], [ 633, 651 ], [ 671, 679 ] ] }, { "plaintext": "The dominant type of defect of concern in quartz crystals is the substitution of an Al(III) for a Si(IV) atom in the crystal lattice. The aluminium ion has an associated interstitial charge compensator present nearby, which can be a H+ ion (attached to the nearby oxygen and forming a hydroxyl group, called Al−OH defect), Li+ ion, Na+ ion, K+ ion (less common), or an electron hole trapped in a nearby oxygen atom orbital. The composition of the growth solution, whether it is based on lithium or sodium alkali compounds, determines the charge compensating ions for the aluminium defects. The ion impurities are of concern as they are not firmly bound and can migrate through the crystal, altering the local lattice elasticity and the resonant frequency of the crystal. Other common impurities of concern are e.g. iron(III) (interstitial), fluorine, boron(III), phosphorus(V) (substitution), titanium(IV) (substitution, universally present in magmatic quartz, less common in hydrothermal quartz), and germanium(IV) (substitution). Sodium and iron ions can cause inclusions of acnite and elemeusite crystals. Inclusions of water may be present in fast-grown crystals; interstitial water molecules are abundant near the crystal seed. Another defect of importance is the hydrogen containing growth defect, when instead of a Si−O−Si structure, a pair of Si−OH HO−Si groups is formed; essentially a hydrolyzed bond. Fast-grown crystals contain more hydrogen defects than slow-grown ones. These growth defects source as supply of hydrogen ions for radiation-induced processes and forming Al-OH defects. Germanium impurities tend to trap electrons created during irradiation; the alkali metal cations then migrate towards the negatively charged center and form a stabilizing complex. Matrix defects can also be present; oxygen vacancies, silicon vacancies (usually compensated by 4 hydrogens or 3 hydrogens and a hole), peroxy groups, etc. Some of the defects produce localized levels in the forbidden band, serving as charge traps; Al(III) and B(III) typically serve as hole traps while electron vacancies, titanium, germanium, and phosphorus atoms serve as electron traps. The trapped charge carriers can be released by heating; their recombination is the cause of thermoluminescence.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 7849, 904, 27114, 661808, 13255, 14386, 17561, 26826, 23055, 142534, 747200, 2054659, 537975 ], "anchor_spans": [ [ 21, 27 ], [ 84, 91 ], [ 98, 104 ], [ 117, 132 ], [ 233, 235 ], [ 285, 299 ], [ 323, 326 ], [ 332, 335 ], [ 341, 343 ], [ 369, 382 ], [ 1063, 1073 ], [ 1077, 1083 ], [ 2261, 2279 ] ] }, { "plaintext": "The mobility of interstitial ions depends strongly on temperature. Hydrogen ions are mobile down to 10 K, but alkali metal ions become mobile only at temperatures around and above 200 K.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The hydroxyl defects can be measured by near-infrared spectroscopy. The trapped holes can be measured by electron spin resonance. The Al−Na+ defects show as an acoustic loss peak due to their stress-induced motion; the Al−Li+ defects do not form a potential well so are not detectable this way. Some of the radiation-induced defects during their thermal annealing produce thermoluminescence; defects related to aluminium, titanium, and germanium can be distinguished.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 1926015, 537975 ], "anchor_spans": [ [ 105, 128 ], [ 372, 390 ] ] }, { "plaintext": "Swept crystals are crystals that have undergone a solid-state electrodiffusion purification process. Sweeping involves heating the crystal above 500°C in a hydrogen-free atmosphere, with a voltage gradient of at least 1 kV/cm, for several hours (usually over 12). The migration of impurities and the gradual replacement of alkali metal ions with hydrogen (when swept in air) or electron holes (when swept in vacuum) causes a weak electric current through the crystal; decay of this current to a constant value signals the end of the process. The crystal is then left to cool, while the electric field is maintained. The impurities are concentrated at the cathode region of the crystal, which is cut off afterwards and discarded. Swept crystals have increased resistance to radiation, as the dose effects are dependent on the level of alkali metal impurities; they are suitable for use in devices exposed to ionizing radiation, e.g. for nuclear and space technology. Sweeping under vacuum at higher temperatures and higher field strengths yields yet more radiation-hard crystals. The level and character of impurities can be measured by infrared spectroscopy. Quartz can be swept in both α and β phase; sweeping in β phase is faster, but the phase transition may induce twinning. Twinning can be mitigated by subjecting the crystal to compression stress in the X direction, or an AC or DC electric field along the X axis while the crystal cools through the phase transformation temperature region.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 8643 ], "anchor_spans": [ [ 62, 78 ] ] }, { "plaintext": "Sweeping can also be used to introduce one kind of an impurity into the crystal. Lithium, sodium, and hydrogen swept crystals are used for, e.g., studying quartz behavior.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Very small crystals for high fundamental-mode frequencies can be manufactured by photolithography.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Crystals can be adjusted to exact frequencies by laser trimming. A technique used in the world of amateur radio for slight decrease of the crystal frequency may be achieved by exposing crystals with silver electrodes to vapors of iodine, which causes a slight mass increase on the surface by forming a thin layer of silver iodide; such crystals however had problematic long-term stability. Another method commonly used is electrochemical increase or decrease of silver electrode thickness by submerging a resonator in lapis lazuli dissolved in water, citric acid in water, or water with salt, and using the resonator as one electrode, and a small silver electrode as the other.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 1758144, 23275402, 14750, 449669, 44653 ], "anchor_spans": [ [ 49, 63 ], [ 98, 111 ], [ 230, 236 ], [ 316, 329 ], [ 518, 530 ] ] }, { "plaintext": "By choosing the direction of current one can either increase or decrease the mass of the electrodes.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Details were published in \"Radio\" magazine (3/1978) by UB5LEV.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Raising frequency by scratching off parts of the electrodes is not advised as this may damage the crystal and lower its Q factor. Capacitor trimmers can be also used for frequency adjustment of the oscillator circuit.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 229160, 8983270 ], "anchor_spans": [ [ 120, 128 ], [ 140, 147 ] ] }, { "plaintext": "Some other piezoelectric materials than quartz can be employed. These include single crystals of lithium tantalate, lithium niobate, lithium borate, berlinite, gallium arsenide, lithium tetraborate, aluminium phosphate, bismuth germanium oxide, polycrystalline zirconium titanate ceramics, high-alumina ceramics, silicon-zinc oxide composite, or dipotassium tartrate. Some materials may be more suitable for specific applications. An oscillator crystal can be also manufactured by depositing the resonator material on the silicon chip surface. Crystals of gallium phosphate, langasite, langanite and langatate are about 10 times more pullable than the corresponding quartz crystals, and are used in some VCXO oscillators.", "section_idx": 7, "section_name": "Crystal structures and materials", "target_page_ids": [ 24975, 2067016, 3243489, 2009397, 20034744, 144143, 2009397, 5022681, 4602758, 27114, 515339, 198182, 6681252, 2624309 ], "anchor_spans": [ [ 11, 33 ], [ 97, 114 ], [ 116, 131 ], [ 133, 147 ], [ 149, 158 ], [ 160, 176 ], [ 178, 197 ], [ 199, 218 ], [ 220, 243 ], [ 313, 320 ], [ 321, 331 ], [ 346, 366 ], [ 556, 573 ], [ 575, 584 ] ] }, { "plaintext": "The frequency stability is determined by the crystal's Q. It is inversely dependent on the frequency, and on the constant that is dependent on the particular cut. Other factors influencing Q are the overtone used, the temperature, the level of driving of the crystal, the quality of the surface finish, the mechanical stresses imposed on the crystal by bonding and mounting, the geometry of the crystal and the attached electrodes, the material purity and defects in the crystal, type and pressure of the gas in the enclosure, interfering modes, and presence and absorbed dose of ionizing and neutron radiation.", "section_idx": 8, "section_name": "Stability", "target_page_ids": [ 229160 ], "anchor_spans": [ [ 55, 56 ] ] }, { "plaintext": "Temperature influences the operating frequency; various forms of compensation are used, from analog compensation (TCXO) and microcontroller compensation (MCXO) to stabilization of the temperature with a crystal oven (OCXO). The crystals possess temperature hysteresis; the frequency at a given temperature achieved by increasing the temperature is not equal to the frequency on the same temperature achieved by decreasing the temperature. The temperature sensitivity depends primarily on the cut; the temperature compensated cuts are chosen as to minimize frequency/temperature dependence. Special cuts can be made with linear temperature characteristics; the LC cut is used in quartz thermometers. Other influencing factors are the overtone used, the mounting and electrodes, impurities in the crystal, mechanical strain, crystal geometry, rate of temperature change, thermal history (due to hysteresis), ionizing radiation, and drive level.", "section_idx": 8, "section_name": "Stability", "target_page_ids": [ 2602534, 147003 ], "anchor_spans": [ [ 203, 215 ], [ 257, 267 ] ] }, { "plaintext": "Crystals tend to suffer anomalies in their frequency/temperature and resistance/temperature characteristics, known as activity dips. These are small downward frequency or upward resistance excursions localized at certain temperatures, with their temperature position dependent on the value of the load capacitors.", "section_idx": 8, "section_name": "Stability", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Mechanical stresses also influence the frequency. The stresses can be induced by mounting, bonding, and application of the electrodes, by differential thermal expansion of the mounting, electrodes, and the crystal itself, by differential thermal stresses when there is a temperature gradient present, by expansion or shrinkage of the bonding materials during curing, by the air pressure that is transferred to the ambient pressure within the crystal enclosure, by the stresses of the crystal lattice itself (nonuniform growth, impurities, dislocations), by the surface imperfections and damage caused during manufacture, and by the action of gravity on the mass of the crystal; the frequency can therefore be influenced by position of the crystal. Other dynamic stress inducing factors are shocks, vibrations, and acoustic noise. Some cuts are less sensitive to stresses; the SC (Stress Compensated) cut is an example. Atmospheric pressure changes can also introduce deformations to the housing, influencing the frequency by changing stray capacitances.", "section_idx": 8, "section_name": "Stability", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Atmospheric humidity influences the thermal transfer properties of air, and can change electrical properties of plastics by diffusion of water molecules into their structure, altering the dielectric constants and electrical conductivity.", "section_idx": 8, "section_name": "Stability", "target_page_ids": [ 53781, 61580 ], "anchor_spans": [ [ 188, 207 ], [ 213, 236 ] ] }, { "plaintext": "Other factors influencing the frequency are the power supply voltage, load impedance, magnetic fields, electric fields (in case of cuts that are sensitive to them, e.g., SC cuts), the presence and absorbed dose of γ-particles and ionizing radiation, and the age of the crystal.", "section_idx": 8, "section_name": "Stability", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Crystals undergo slow gradual change of frequency with time, known as aging. There are many mechanisms involved. The mounting and contacts may undergo relief of the built-in stresses. Molecules of contamination either from the residual atmosphere, outgassed from the crystal, electrodes or packaging materials, or introduced during sealing the housing can be adsorbed on the crystal surface, changing its mass; this effect is exploited in quartz crystal microbalances. The composition of the crystal can be gradually altered by outgassing, diffusion of atoms of impurities or migrating from the electrodes, or the lattice can be damaged by radiation. Slow chemical reactions may occur on or in the crystal, or on the inner surfaces of the enclosure. Electrode material, e.g. chromium or aluminium, can react with the crystal, creating layers of metal oxide and silicon; these interface layers can undergo changes in time. The pressure in the enclosure can change due to varying atmospheric pressure, temperature, leaks, or outgassing of the materials inside. Factors outside of the crystal itself are e.g. aging of the oscillator circuitry (and e.g. change of capacitances), and drift of parameters of the crystal oven. External atmosphere composition can also influence the aging; hydrogen can diffuse through nickel housing. Helium can cause similar issues when it diffuses through glass enclosures of rubidium standards.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 774575, 1236075, 13255, 41674 ], "anchor_spans": [ [ 248, 257 ], [ 439, 466 ], [ 1282, 1290 ], [ 1404, 1421 ] ] }, { "plaintext": "Gold is a favored electrode material for low-aging resonators; its adhesion to quartz is strong enough to maintain contact even at strong mechanical shocks, but weak enough to not support significant strain gradients (unlike chromium, aluminium, and nickel). Gold also does not form oxides; it adsorbs organic contaminants from the air, but these are easy to remove. However, gold alone can undergo delamination; a layer of chromium is therefore sometimes used for improved binding strength. Silver and aluminium are often used as electrodes; however both form oxide layers with time that increases the crystal mass and lowers frequency. Silver can be passivated by exposition to iodine vapors, forming a layer of silver iodide. Aluminium oxidizes readily but slowly, until about 5nm thickness is reached; increased temperature during artificial aging does not significantly increase the oxide forming speed; a thick oxide layer can be formed during manufacture by anodizing. Exposition of silver-plated crystal to iodine vapors can also be used in amateur conditions for lowering the crystal frequency slightly; the frequency can also be increased by scratching off parts of the electrodes, but that carries risk of damage to the crystal and loss of Q.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 14750, 449669, 831650 ], "anchor_spans": [ [ 680, 686 ], [ 714, 727 ], [ 965, 974 ] ] }, { "plaintext": "A DC voltage bias between the electrodes can accelerate the initial aging, probably by induced diffusion of impurities through the crystal. Placing a capacitor in series with the crystal and a several-megaohm resistor in parallel can minimize such voltages.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Crystals are sensitive to shock. The mechanical stress causes a short-term change in the oscillator frequency due to the stress-sensitivity of the crystal, and can introduce a permanent change of frequency due to shock-induced changes of mounting and internal stresses (if the elastic limits of the mechanical parts are exceeded), desorption of contamination from the crystal surfaces, or change in parameters of the oscillator circuit. High magnitudes of shocks may tear the crystals off their mountings (especially in the case of large low-frequency crystals suspended on thin wires), or cause cracking of the crystal. Crystals free of surface imperfections are highly shock-resistant; chemical polishing can produce crystals able to survive tens of thousands of g.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 159081, 8726682, 389836 ], "anchor_spans": [ [ 26, 31 ], [ 688, 706 ], [ 765, 766 ] ] }, { "plaintext": "Crystals suffer from minor short-term frequency fluctuations as well. The main causes of such noise are e.g. thermal noise (which limits the noise floor), phonon scattering (influenced by lattice defects), adsorption/desorption of molecules on the surface of the crystal, noise of the oscillator circuits, mechanical shocks and vibrations, acceleration and orientation changes, temperature fluctuations, and relief of mechanical stresses. The short-term stability is measured by four main parameters: Allan variance (the most common one specified in oscillator data sheets), phase noise, spectral density of phase deviations, and spectral density of fractional frequency deviations. The effects of acceleration and vibration tend to dominate the other noise sources; surface acoustic wave devices tend to be more sensitive than bulk acoustic wave (BAW) ones, and the stress-compensated cuts are even less sensitive. The relative orientation of the acceleration vector to the crystal dramatically influences the crystal's vibration sensitivity. Mechanical vibration isolation mountings can be used for high-stability crystals.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 182745, 24540472, 40708 ], "anchor_spans": [ [ 109, 122 ], [ 155, 172 ], [ 501, 515 ] ] }, { "plaintext": "Phase noise plays a significant role in frequency synthesis systems using frequency multiplication; a multiplication of a frequency by N increases the phase noise power by N2. A frequency multiplication by 10 times multiplies the magnitude of the phase error by 10 times. This can be disastrous for systems employing PLL or FSK technologies.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 41549, 10792995, 41548, 41193 ], "anchor_spans": [ [ 0, 11 ], [ 40, 59 ], [ 317, 320 ], [ 324, 327 ] ] }, { "plaintext": "Crystals are somewhat sensitive to radiation damage. Natural quartz is much more sensitive than artificially grown crystals, and sensitivity can be further reduced by sweeping the crystal – heating the crystal to at least 400°C in a hydrogen-free atmosphere in an electric field of at least 500V/cm for at least 12 hours. Such swept crystals have a very low response to steady ionizing radiation. Some Si(IV) atoms are replaced with Al(III) impurities, each having a compensating Li+ or Na+ cation nearby. Ionization produces electron-hole pairs; the holes are trapped in the lattice near the Al atom, the resulting Li and Na atoms are loosely trapped along the Z axis; the change of the lattice near the Al atom and the corresponding elastic constant then causes a corresponding change in frequency. Sweeping removes the Li+ and Na+ ions from the lattice, reducing this effect. The Al3+ site can also trap hydrogen atoms. All crystals have a transient negative frequency shift after exposure to an X-ray pulse; the frequency then shifts gradually back; natural quartz reaches stable frequency after 10–1000 seconds, with a negative offset to pre-irradiation frequency, artificial crystals return to a frequency slightly lower or higher than pre-irradiation, swept crystals anneal virtually back to original frequency. The annealing is faster at higher temperatures. Sweeping under vacuum at higher temperatures and field strength can further reduce the crystal's response to X-ray pulses. Series resistance of unswept crystals increases after an X-ray dose, and anneals back to a somewhat higher value for a natural quartz (requiring a corresponding gain reserve in the circuit) and back to pre-irradiation value for synthetic crystals. Series resistance of swept crystals is unaffected. Increase of series resistance degrades Q; too high increase can stop the oscillations. Neutron radiation induces frequency changes by introducing dislocations into the lattice by knocking out atoms, a single fast neutron can produce many defects; the SC and AT cut frequency increases roughly linearly with absorbed neutron dose, while the frequency of the BT cuts decreases. Neutrons also alter the temperature-frequency characteristics. Frequency change at low ionizing radiation doses is proportionally higher than for higher doses. High-intensity radiation can stop the oscillator by inducing photoconductivity in the crystal and transistors; with a swept crystal and properly designed circuit the oscillations can restart within 15 microseconds after the radiation burst. Quartz crystals with high levels of alkali metal impurities lose Q with irradiation; Q of swept artificial crystals is unaffected. Irradiation with higher doses (over 105 rad) lowers sensitivity to subsequent doses. Very low radiation doses (below 300 rad) have disproportionately higher effect, but this nonlinearity saturates at higher doses. At very high doses, the radiation response of the crystal saturates as well, due to the finite number of impurity sites that can be affected.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 9934503, 27114, 904, 17561, 26826, 34197, 410923, 3770784, 60885 ], "anchor_spans": [ [ 35, 51 ], [ 402, 408 ], [ 433, 440 ], [ 480, 483 ], [ 487, 490 ], [ 999, 1004 ], [ 1876, 1893 ], [ 1997, 2009 ], [ 2386, 2403 ] ] }, { "plaintext": "Magnetic fields have little effect on the crystal itself, as quartz is diamagnetic; eddy currents or AC voltages can however be induced into the circuits, and magnetic parts of the mounting and housing may be influenced.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 36563, 8315, 465008 ], "anchor_spans": [ [ 0, 14 ], [ 71, 82 ], [ 84, 96 ] ] }, { "plaintext": "After the power-up, the crystals take several seconds to minutes to \"warm up\" and stabilize their frequency. The oven-controlled OCXOs require usually 3–10 minutes for heating up to reach thermal equilibrium; the oven-less oscillators stabilize in several seconds as the few milliwatts dissipated in the crystal cause a small but noticeable level of internal heating.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Crystals have no inherent failure mechanisms; some have operated in devices for decades. Failures may be, however, introduced by faults in bonding, leaky enclosures, corrosion, frequency shift by aging, breaking the crystal by too high mechanical shock, or radiation-induced damage when nonswept quartz is used. Crystals can be also damaged by overdriving.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The crystals have to be driven at the appropriate drive level. While AT cuts tend to be fairly forgiving, with only their electrical parameters, stability and aging characteristics being degraded when overdriven, low-frequency crystals, especially flexural-mode ones, may fracture at too high drive levels. The drive level is specified as the amount of power dissipated in the crystal. The appropriate drive levels are about 5 μW for flexural modes up to 100kHz, 1 μW for fundamental modes at 1–4MHz, 0.5 μW for fundamental modes 4–20MHz and 0.5 μW for overtone modes at 20–200MHz. Too low drive level may cause problems with starting the oscillator. Low drive levels are better for higher stability and lower power consumption of the oscillator. Higher drive levels, in turn, reduce the impact of noise by increasing the signal-to-noise ratio.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 41706 ], "anchor_spans": [ [ 822, 843 ] ] }, { "plaintext": "The stability of AT cut crystals decreases with increasing frequency. For more accurate higher frequencies it is better to use a crystal with lower fundamental frequency, operating at an overtone.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Aging decreases logarithmically with time, the largest changes occurring shortly after manufacture. Artificially aging a crystal by prolonged storage at 85 to 125°C can increase its long-term stability.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A badly designed oscillator circuit may suddenly begin oscillating on an overtone. In 1972, a train in Fremont, California crashed due to a faulty oscillator. An inappropriate value of the tank capacitor caused the crystal in a control board to be overdriven, jumping to an overtone, and causing the train to speed up instead of slowing down.", "section_idx": 9, "section_name": "Aging", "target_page_ids": [ 41480, 52826 ], "anchor_spans": [ [ 73, 81 ], [ 103, 122 ] ] }, { "plaintext": "The resonator plate can be cut from the source crystal in many different ways. The orientation of the cut influences the crystal's aging characteristics, frequency stability, thermal characteristics, and other parameters. These cuts operate at bulk acoustic wave (BAW); for higher frequencies, surface acoustic wave (SAW) devices are employed.", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [ 459844 ], "anchor_spans": [ [ 294, 315 ] ] }, { "plaintext": "Image of several crystal cuts", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The T in the cut name marks a temperature-compensated cut, a cut oriented in a way that the temperature coefficients of the lattice are minimal; the FC and SC cuts are also temperature-compensated.", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The high frequency cuts are mounted by their edges, usually on springs; the stiffness of the spring has to be optimal, as if it is too stiff, mechanical shocks could be transferred to the crystal and cause it to break, and too little stiffness may allow the crystal to collide with the inside of the package when subjected to a mechanical shock, and break. Strip resonators, usually AT cuts, are smaller and therefore less sensitive to mechanical shocks. At the same frequency and overtone, the strip has less pullability, higher resistance, and higher temperature coefficient.", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The low frequency cuts are mounted at the nodes where they are virtually motionless; thin wires are attached at such points on each side between the crystal and the leads. The large mass of the crystal suspended on the thin wires makes the assembly sensitive to mechanical shocks and vibrations.", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The crystals are usually mounted in hermetically sealed glass or metal cases, filled with a dry and inert atmosphere, usually vacuum, nitrogen, or helium. Plastic housings can be used as well, but those are not hermetic and another secondary sealing has to be built around the crystal.", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Several resonator configurations are possible, in addition to the classical way of directly attaching leads to the crystal. E.g. the BVA resonator (Boîtier à Vieillissement Amélioré, Enclosure with Improved Aging), developed in 1976; the parts that influence the vibrations are machined from a single crystal (which reduces the mounting stress), and the electrodes are deposited not on the resonator itself but on the inner sides of two condenser discs made of adjacent slices of the quartz from the same bar, forming a three-layer sandwich with no stress between the electrodes and the vibrating element. The gap between the electrodes and the resonator act as two small series capacitors, making the crystal less sensitive to circuit influences. The architecture eliminates the effects of the surface contacts between the electrodes, the constraints in the mounting connections, and the issues related to ion migration from the electrodes into the lattice of the vibrating element. The resulting configuration is rugged, resistant to shock and vibration, resistant to acceleration and ionizing radiation, and has improved aging characteristics. AT cut is usually used, though SC cut variants exist as well. BVA resonators are often used in spacecraft applications.", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the 1930s to 1950s, it was fairly common for people to adjust the frequency of the crystals by manual grinding. The crystals were ground using a fine abrasive slurry, or even a toothpaste, to increase their frequency. A slight decrease by 1–2kHz when the crystal was overground was possible by marking the crystal face with a pencil lead, at the cost of a lowered Q.", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The frequency of the crystal is slightly adjustable (\"pullable\") by modifying the attached capacitances. A varactor, a diode with capacitance depending on applied voltage, is often used in voltage-controlled crystal oscillators, VCXO. The crystal cuts are usually AT or rarely SC, and operate in fundamental mode; the amount of available frequency deviation is inversely proportional to the square of the overtone number, so a third overtone has only one-ninth of the pullability of the fundamental mode. SC cuts, while more stable, are significantly less pullable.", "section_idx": 10, "section_name": "Crystal cuts", "target_page_ids": [ 231506 ], "anchor_spans": [ [ 107, 115 ] ] }, { "plaintext": "On electrical schematic diagrams, crystals are designated with the class letter Y (Y1, Y2, etc.). Oscillators, whether they are crystal oscillators or others, are designated with the class letter G (G1, G2, etc.). Crystals may also be designated on a schematic with X or XTAL, or a crystal oscillator with XO.", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Crystal oscillator types and their abbreviations:", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "ATCXO — Analog temperature controlled crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [ 5721990 ], "anchor_spans": [ [ 8, 56 ] ] }, { "plaintext": "CDXO — Calibrated dual crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "DTCXO — Digital temperature compensated crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "EMXO — Evacuated miniature crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "GPSDO — Global positioning system disciplined oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [ 33488024 ], "anchor_spans": [ [ 8, 56 ] ] }, { "plaintext": "MCXO — Microcomputer-compensated crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [ 48144 ], "anchor_spans": [ [ 7, 20 ] ] }, { "plaintext": "OCVCXO — oven-controlled voltage-controlled crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [ 2602534 ], "anchor_spans": [ [ 9, 24 ] ] }, { "plaintext": "OCXO — Oven-controlled crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [ 2602534 ], "anchor_spans": [ [ 7, 41 ] ] }, { "plaintext": "RbXO — Rubidium crystal oscillators (RbXO), a crystal oscillator (can be an MCXO) synchronized with a built-in rubidium standard which is run only occasionally to save power", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [ 25599, 41674 ], "anchor_spans": [ [ 7, 15 ], [ 111, 128 ] ] }, { "plaintext": "TCVCXO — Temperature-compensated voltage-controlled crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [ 599563 ], "anchor_spans": [ [ 33, 70 ] ] }, { "plaintext": "TCXO — Temperature-compensated crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "TMXO – Tactical miniature crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "TSXO — Temperature-sensing crystal oscillator, an adaptation of the TCXO", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "VCTCXO — Voltage-controlled temperature-compensated crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "VCXO — Voltage-controlled crystal oscillator", "section_idx": 11, "section_name": "Circuit notations and abbreviations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Clock generator", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 379803 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Clock drift – Clock drift measurements of crystal oscillators can be used to build random number generators.", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 6083924, 2736939 ], "anchor_spans": [ [ 0, 11 ], [ 83, 106 ] ] }, { "plaintext": "Crystal filter", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 234088 ], "anchor_spans": [ [ 0, 14 ] ] }, { "plaintext": "Erhard Kietz work on electronic tuning forks and with quartz crystals for precise signal frequencies", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 25820999 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": " Issac Koga – inventor of the temperature-stable R1 Koga cut", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 45042916 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": "Pierce oscillator", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 5172172 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Quartz crystal microbalance using crystal oscillators for weighing extremely small amounts.", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 1236075 ], "anchor_spans": [ [ 0, 27 ] ] }, { "plaintext": "Thin-film thickness monitor", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 31950254 ], "anchor_spans": [ [ 0, 27 ] ] }, { "plaintext": "VFO — variable-frequency oscillator", "section_idx": 12, "section_name": "See also", "target_page_ids": [ 436166 ], "anchor_spans": [ [ 0, 3 ] ] }, { "plaintext": " (Alternative downloads: QSL: - 0 1 2 3 4 5 6 7 8 9 10. AXTAL ZIP: - 0 1 2 3 4 5 6 7 8 9 10.)", "section_idx": 14, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Introduction to quartz frequency standards", "section_idx": 15, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Distortions in Crystal Oscillators", "section_idx": 15, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Quartz crystal resonators and oscillators", "section_idx": 15, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Multipage summary of quartz crystals & their oscillators, filters, etc", "section_idx": 15, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Resonators", "Electronic_oscillators" ]

[]

[ { "plaintext": "Curve-fitting compaction is data compaction accomplished by replacing data to be stored or transmitted with an analytical expression.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40991, 585143 ], "anchor_spans": [ [ 29, 44 ], [ 112, 133 ] ] }, { "plaintext": "Examples of curve-fitting compaction consisting of discretization and then interpolation are:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 330017, 14569 ], "anchor_spans": [ [ 51, 65 ], [ 75, 88 ] ] }, { "plaintext": " Breaking of a continuous curve into a series of straight line segments and specifying the slope, intercept, and range for each segment ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 29368, 464331 ], "anchor_spans": [ [ 91, 96 ], [ 98, 107 ] ] }, { "plaintext": " Using a mathematical expression, such as a polynomial or a trigonometric function, and a single point on the corresponding curve instead of storing or transmitting the entire graphic curve or a series of points on it.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609125, 23000, 30367 ], "anchor_spans": [ [ 22, 32 ], [ 44, 54 ], [ 60, 82 ] ] } ]

[ "Curves", "Interpolation", "Data_compression" ]

[]

[ { "plaintext": "In telecommunications, the term customer office terminal has the following meanings:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "1. Termination equipment that (a) is located on the customer premises and (b) performs a function that may be integrated into the common carrier equipment.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40910 ], "anchor_spans": [ [ 130, 144 ] ] }, { "plaintext": "Note: An example of a customer office terminal is a stand-alone multiplexer located on the customer premises. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 38542 ], "anchor_spans": [ [ 65, 76 ] ] }, { "plaintext": "2. The digital loop carrier (DLC) multiplexing function that is near the exchange termination (ET) when provided by a stand-alone multiplexer.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1878839, 41389 ], "anchor_spans": [ [ 7, 27 ], [ 34, 46 ] ] }, { "plaintext": "Note: This function may be integrated into the ET.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telecommunications_equipment" ]

[]

[ { "plaintext": "In telecommunications, a customer-premises equipment or customer-provided equipment (CPE) is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication circuit at the demarcation point (\"demarc\"). The demarc is a point established in a building or complex to separate customer equipment from the equipment located in either the distribution infrastructure or central office of the communications service provider.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 460792, 259338, 40910, 346001, 250347, 26668156, 47005 ], "anchor_spans": [ [ 3, 21 ], [ 97, 105 ], [ 144, 156 ], [ 187, 196 ], [ 197, 222 ], [ 230, 247 ], [ 422, 436 ], [ 444, 475 ] ] }, { "plaintext": "CPE generally refers to devices such as telephones, routers, network switches, residential gateways (RG), set-top boxes, fixed mobile convergence products, home networking adapters and Internet access gateways that enable consumers to access providers' communication services and distribute them in a residence or enterprise with a local area network (LAN).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 25748, 40614, 6959783, 29580, 16443289, 3509706, 1338556, 17739 ], "anchor_spans": [ [ 52, 58 ], [ 61, 75 ], [ 79, 98 ], [ 106, 117 ], [ 121, 145 ], [ 156, 168 ], [ 201, 209 ], [ 332, 350 ] ] }, { "plaintext": "A CPE can be an active equipment, as the ones mentioned above, or passive equipment such as analogue telephone adapters (ATA) or xDSL-splitters. This includes key telephone systems and most private branch exchanges. Excluded from the CPE category are overvoltage protection equipment and pay telephones. Other types of materials that are necessary for the delivery of the telecommunication service, but are not defined as equipment, such as manuals and cable packages, and cable adapters are instead referred to as CPE-peripherals.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1017561, 1017561, 2074176, 163387 ], "anchor_spans": [ [ 160, 180 ], [ 191, 214 ], [ 253, 264 ], [ 290, 303 ] ] }, { "plaintext": "CPE can refer to devices purchased by the subscriber, or to those provided by the operator or service provider.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The two phrases, \"customer-premises equipment\" and \"customer-provided equipment\", reflect the history of this equipment.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Under the Bell System monopoly in the United States (post Communications Act of 1934), the Bell System owned the telephones, and one could not attach privately owned or supplied devices to the network, or to the station apparatus. Telephones were located on customers' premises, hence, customer-premises equipment. In the U.S. Federal Communications Commission (FCC) proceeding the Second Computer Inquiry, the FCC ruled that telecommunications carriers could no longer bundle CPE with telecommunications service, uncoupling the market power of the telecommunications service monopoly from the CPE market, and creating a competitive CPE market.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 21347591, 66040, 55974, 17208389 ], "anchor_spans": [ [ 10, 21 ], [ 58, 84 ], [ 328, 361 ], [ 383, 406 ] ] }, { "plaintext": "With the gradual breakup of the Bell monopoly, starting with Hush-A-Phone v. United States [1956], which allowed some non-Bell owned equipment to be connected to the network (a process called interconnection), equipment on customers' premises became increasingly owned by customers. Indeed, subscribers were eventually permitted to purchase telephones – hence, customer-provided equipment.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 2175790, 1702294 ], "anchor_spans": [ [ 61, 90 ], [ 192, 207 ] ] }, { "plaintext": "In the pay-TV industry many operators and service providers offer subscribers a set-top box with which to receive video services, in return for a monthly fee. As offerings have evolved to include multiple services [voice and data] operators have increasingly given consumers the opportunity to rent or buy additional devices like access modems, internet gateways and video extenders that enable them to access multiple services, and distribute them to a range of consumer electronics devices in the home.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 29580, 20647197, 189768 ], "anchor_spans": [ [ 80, 91 ], [ 338, 343 ], [ 464, 484 ] ] }, { "plaintext": "The growth of multiple system operators, offering triple or quad-play services, required the development of hybrid CPE to make it easy for subscribers to access voice, video and data services. The development of this technology was led by Pay TV operators looking for a way to deliver video services via both traditional broadcast and broadband IP networks. Spain's Telefonica was the first operator to launch a hybrid broadcast and broadband TV service in 2003 with its Movistar TV DTT/IPTV offering, while Polish satellite operator 'n' was the first to offer its subscribers a Three-way hybrid (or Tri-brid) broadcast and broadband TV service, which launched in 2009", "section_idx": 2, "section_name": "Technology evolution", "target_page_ids": [ 2181454, 661989, 30005, 497303, 1077225, 7748366, 29153686 ], "anchor_spans": [ [ 14, 39 ], [ 239, 245 ], [ 367, 377 ], [ 484, 487 ], [ 488, 492 ], [ 536, 537 ], [ 580, 596 ] ] }, { "plaintext": "The term set-back box is used in the digital TV industry to describe a piece of consumer hardware that enables them to access both linear broadcast and internet-based video content, plus a range of interactive services like Electronic Programme Guides (EPG), Pay Per View (PPV) and video on demand (VOD) as well as internet browsing, and view them on a large screen television set. Unlike standard set-top boxes, which sit on top of or below the TV, a set-back box has a smaller form factor to enable it to be mounted to the rear of the display panel flat panel TV, hiding it from view.", "section_idx": 2, "section_name": "Technology evolution", "target_page_ids": [ 26848475, 1331154, 101733, 147143, 628485 ], "anchor_spans": [ [ 9, 21 ], [ 224, 250 ], [ 259, 271 ], [ 282, 297 ], [ 446, 448 ] ] }, { "plaintext": "A residential gateway is a networking device used to connect devices in the home to the Internet or other wide area network (WAN).", "section_idx": 2, "section_name": "Technology evolution", "target_page_ids": [ 6959783, 38140 ], "anchor_spans": [ [ 2, 21 ], [ 106, 123 ] ] }, { "plaintext": "It is an umbrella term, used to cover multi-function networking appliances used in homes, which may combine a DSL modem or cable modem, a network switch, a consumer-grade router, and a wireless access point. In the past, such functions were provided by separate devices, but in recent years technological convergence has enabled multiple functions to be merged into a single device.", "section_idx": 2, "section_name": "Technology evolution", "target_page_ids": [ 10429990, 2895884, 53259, 40614, 25748, 192397, 206586 ], "anchor_spans": [ [ 64, 74 ], [ 110, 119 ], [ 123, 134 ], [ 138, 152 ], [ 171, 177 ], [ 185, 206 ], [ 291, 316 ] ] }, { "plaintext": "One of the first home gateway devices to be launched was selected by Telecom Italia to enable the operator to offer triple play services in 2002 . Along with a SIP VoIP handset for making voice calls, it enabled subscribers to access voice, video and data services over a 10MB symmetrical ADSL fiber connection.", "section_idx": 2, "section_name": "Technology evolution", "target_page_ids": [ 18934536, 3372377 ], "anchor_spans": [ [ 290, 294 ], [ 295, 300 ] ] }, { "plaintext": "The virtual gateway concept enables consumers to access video and data services and distribute them around their homes using software rather than hardware. The first virtual gateway was introduced in 2010 by Advanced Digital Broadcast at the IBC exhibition in Amsterdam. The ADB Virtual Gateway uses software that resides within the middleware and is based on open standards, including DLNA home networking and the DTCP-IP standard, to ensure that all content, including paid-for encrypted content like Pay TV services, can only be accessed by secure CE devices.", "section_idx": 2, "section_name": "Technology evolution", "target_page_ids": [ 25469171, 1164253, 1134573, 661989 ], "anchor_spans": [ [ 209, 235 ], [ 387, 391 ], [ 416, 423 ], [ 504, 510 ] ] }, { "plaintext": "A subscriber unit, or SU is a broadband radio that is installed at a business or residential location to connect to an access point to send/receive high speed data wired or wirelessly. Devices commonly referred to as a subscriber unit include cable modems, access gateways, home networking adapters and mobile phones.", "section_idx": 3, "section_name": "Broadband", "target_page_ids": [ 192397, 53259 ], "anchor_spans": [ [ 119, 131 ], [ 244, 255 ] ] }, { "plaintext": "CPE may also refer to any devices that terminate a WAN circuit, such as an ISDN, E-carrier/T-carrier, DSL, or metro Ethernet. This includes any customer-owned hardware at the customer's site: routers, firewalls, network switches, PBXs, VoIP gateways, sometimes CSU/DSU and modems.", "section_idx": 4, "section_name": "WAN", "target_page_ids": [ 38140, 15231, 46728, 41779, 41038, 2120578, 25748, 26173989, 40614, 1017561, 75028, 923209, 20647197 ], "anchor_spans": [ [ 51, 54 ], [ 75, 79 ], [ 81, 90 ], [ 91, 100 ], [ 102, 105 ], [ 110, 124 ], [ 192, 198 ], [ 201, 209 ], [ 212, 226 ], [ 230, 233 ], [ 236, 240 ], [ 261, 268 ], [ 273, 278 ] ] }, { "plaintext": "Application areas", "section_idx": 4, "section_name": "WAN", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Connected home", "section_idx": 4, "section_name": "WAN", "target_page_ids": [ 3509706 ], "anchor_spans": [ [ 0, 14 ] ] }, { "plaintext": "Pay TV", "section_idx": 4, "section_name": "WAN", "target_page_ids": [ 661989 ], "anchor_spans": [ [ 0, 6 ] ] }, { "plaintext": "Over-the-top video services", "section_idx": 4, "section_name": "WAN", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Broadband", "section_idx": 4, "section_name": "WAN", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Voice over IP", "section_idx": 4, "section_name": "WAN", "target_page_ids": [ 75028 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Fixed–mobile convergence [FMC]", "section_idx": 4, "section_name": "WAN", "target_page_ids": [ 16443289 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Cellular carriers may sometimes internally refer to cellular phones a customer has purchased without a subsidy or from a third party as \"customer provided equipment.\"", "section_idx": 5, "section_name": "Other uses", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "It is also notable that the fully qualified domain name and the PTR record of DSL and cable lines connected to a residence will often contain 'cpe'.", "section_idx": 5, "section_name": "Other uses", "target_page_ids": [ 706155, 12886486 ], "anchor_spans": [ [ 28, 55 ], [ 64, 74 ] ] }, { "plaintext": "Demarcation point", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 250347 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Interconnection", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 1702294 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "On-premises wiring", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 41445 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "Terminal equipment", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 41786 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "TR-069", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 4646652 ], "anchor_spans": [ [ 0, 6 ] ] } ]

[ "Telephony_equipment" ]

[ "CPE" ]

[ { "plaintext": "In telecommunication, a customer service unit (CSU) is a device that provides an accessing arrangement at a user location to either switched or point-to-point, data-conditioned circuits at a specifically established data signaling rate. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 2052479, 365920, 24540689, 40998 ], "anchor_spans": [ [ 3, 20 ], [ 108, 112 ], [ 144, 158 ], [ 160, 176 ], [ 216, 235 ] ] }, { "plaintext": "A CSU provides local loop equalization, transient protection, isolation, and central office loop-back testing capability.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 160478, 26332696, 26668156, 160478 ], "anchor_spans": [ [ 21, 25 ], [ 26, 38 ], [ 77, 91 ], [ 92, 101 ] ] } ]

[ "Local_loop" ]

[]

[ { "plaintext": "In telecommunications, a cutback technique is a destructive technique for determining certain optical fiber transmission characteristics, such as attenuation and bandwidth.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 3372377, 33301481, 40735, 15612827 ], "anchor_spans": [ [ 3, 21 ], [ 94, 107 ], [ 108, 135 ], [ 146, 157 ], [ 162, 171 ] ] }, { "plaintext": "The measurement technique consists of:", "section_idx": 1, "section_name": "Procedure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "performing the desired measurements on a long length of the fiber under test,", "section_idx": 1, "section_name": "Procedure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "cutting the fiber under test at a point near the launching end,", "section_idx": 1, "section_name": "Procedure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "repeating the measurements on the short length of fiber, and", "section_idx": 1, "section_name": "Procedure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "subtracting the results obtained on the short length to determine the results for the residual long length.", "section_idx": 1, "section_name": "Procedure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The cut should be made to retain 1meter or more of the fiber, in order to establish equilibrium mode distribution conditions for the second measurement. In a multimode fiber, the lack of an equilibrium mode distribution could introduce errors in the measurement due to output coupling effects. In a single-mode fiber, measuring a shorter cutback fiber could result in significant transmission of cladding modes (light carried in the cladding rather than the core of the optical fiber), distorting the measurement. The errors introduced will result in conservative results (i.e., higher transmission losses and lower bandwidths) than would be realized under equilibrium conditions.", "section_idx": 1, "section_name": "Procedure", "target_page_ids": [ 3055674, 2940457, 41716 ], "anchor_spans": [ [ 84, 113 ], [ 158, 173 ], [ 299, 316 ] ] }, { "plaintext": "The benefit of this technique is that it allows measurement of the fiber characteristics without introducing errors due to variation in the launch conditions. For example, the coupling efficiency of the light source is kept consistent between the initial and the cutback measurements.", "section_idx": 2, "section_name": "Benefits", "target_page_ids": [ 2888093 ], "anchor_spans": [ [ 176, 195 ] ] }, { "plaintext": "Several characteristics may be determined using the same test fiber.", "section_idx": 2, "section_name": "Benefits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Since the attenuation is defined as proportional to the logarithm of the ratio between and , where is the power at point and respectively. Using the cutback technique, the power transmitted through a fiber of known length is measured and compared with the same measurement for the same fiber cut to a length of approximately.", "section_idx": 3, "section_name": "Attenuation measurement", "target_page_ids": [ 2970774 ], "anchor_spans": [ [ 108, 113 ] ] }, { "plaintext": "A variation of the cutback technique is the substitution method, in which measurements are made on a full-length of fiber, and then on a short length of fiber having the same characteristics (core size, numerical aperture), with the results from the short length being subtracted to give the results for the full length.", "section_idx": 4, "section_name": "Related techniques", "target_page_ids": [ 41757, 3372377, 41432 ], "anchor_spans": [ [ 44, 63 ], [ 192, 196 ], [ 203, 221 ] ] }, { "plaintext": "Optical Fiber Measurements", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Fiber_optics" ]

[]

[ { "plaintext": "In physics and electrical engineering, a cutoff frequency, corner frequency, or break frequency is a boundary in a system's frequency response at which energy flowing through the system begins to be reduced (attenuated or reflected) rather than passing through.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22939, 9531, 302033, 40735 ], "anchor_spans": [ [ 3, 10 ], [ 15, 37 ], [ 124, 142 ], [ 208, 218 ] ] }, { "plaintext": "Typically in electronic systems such as filters and communication channels, cutoff frequency applies to an edge in a lowpass, highpass, bandpass, or band-stop characteristic – a frequency characterizing a boundary between a passband and a stopband. It is sometimes taken to be the point in the filter response where a transition band and passband meet, for example, as defined by a half-power point (a frequency for which the output of the circuit is −3dB of the nominal passband value). Alternatively, a stopband corner frequency may be specified as a point where a transition band and a stopband meet: a frequency for which the attenuation is larger than the required stopband attenuation, which for example may be 30dB or 100dB.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 23434533, 156700, 56484, 56486, 254930, 380487, 41488, 41749, 4099733, 4020102, 8410 ], "anchor_spans": [ [ 40, 47 ], [ 52, 73 ], [ 117, 124 ], [ 126, 134 ], [ 136, 144 ], [ 149, 158 ], [ 224, 232 ], [ 239, 247 ], [ 318, 333 ], [ 382, 398 ], [ 453, 455 ] ] }, { "plaintext": "In the case of a waveguide or an antenna, the cutoff frequencies correspond to the lower and upper cutoff wavelengths.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41863, 187317 ], "anchor_spans": [ [ 17, 26 ], [ 33, 40 ] ] }, { "plaintext": "In electronics, cutoff frequency or corner frequency is the frequency either above or below which the power output of a circuit, such as a line, amplifier, or electronic filter has fallen to a given proportion of the power in the passband. Most frequently this proportion is one half the passband power, also referred to as the 3dB point since a fall of 3dB corresponds approximately to half power. As a voltage ratio this is a fall to of the passband voltage. Other ratios besides the 3dB point may also be relevant, for example see Chebyshev Filters below.", "section_idx": 1, "section_name": "Electronics", "target_page_ids": [ 9663, 10779, 8707643, 946963, 1866533, 41488, 8410 ], "anchor_spans": [ [ 3, 14 ], [ 60, 69 ], [ 120, 127 ], [ 139, 143 ], [ 159, 176 ], [ 230, 238 ], [ 330, 332 ] ] }, { "plaintext": "The transfer function for the simplest low-pass filter,", "section_idx": 1, "section_name": "Electronics", "target_page_ids": [ 31146, 56484 ], "anchor_spans": [ [ 4, 21 ], [ 39, 54 ] ] }, { "plaintext": "has a single pole at . The magnitude of this function in the plane is", "section_idx": 1, "section_name": "Electronics", "target_page_ids": [ 81560 ], "anchor_spans": [ [ 13, 17 ] ] }, { "plaintext": "At cutoff", "section_idx": 1, "section_name": "Electronics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Hence, the cutoff frequency is given by", "section_idx": 1, "section_name": "Electronics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Where is the s-plane variable, is angular frequency and is the imaginary unit.", "section_idx": 1, "section_name": "Electronics", "target_page_ids": [ 18610, 199829, 52358 ], "anchor_spans": [ [ 14, 21 ], [ 36, 53 ], [ 66, 80 ] ] }, { "plaintext": "Sometimes other ratios are more convenient than the 3dB point. For instance, in the case of the Chebyshev filter it is usual to define the cutoff frequency as the point after the last peak in the frequency response at which the level has fallen to the design value of the passband ripple. The amount of ripple in this class of filter can be set by the designer to any desired value, hence the ratio used could be any value.", "section_idx": 1, "section_name": "Electronics", "target_page_ids": [ 327003 ], "anchor_spans": [ [ 97, 113 ] ] }, { "plaintext": "In radio communication, skywave communication is a technique in which radio waves are transmitted at an angle into the sky and reflected back to Earth by layers of charged particles in the ionosphere. In this context, the term cutoff frequency refers to the maximum usable frequency, the frequency above which a radio wave fails to reflect off the ionosphere at the incidence angle required for transmission between two specified points by reflection from the layer.", "section_idx": 2, "section_name": "Radio communications", "target_page_ids": [ 15368428, 276281, 98132, 15097, 41359 ], "anchor_spans": [ [ 3, 22 ], [ 24, 31 ], [ 70, 80 ], [ 189, 199 ], [ 259, 283 ] ] }, { "plaintext": "The cutoff frequency of an electromagnetic waveguide is the lowest frequency for which a mode will propagate in it. In fiber optics, it is more common to consider the cutoff wavelength, the maximum wavelength that will propagate in an optical fiber or waveguide. The cutoff frequency is found with the characteristic equation of the Helmholtz equation for electromagnetic waves, which is derived from the electromagnetic wave equation by setting the longitudinal wave number equal to zero and solving for the frequency. Thus, any exciting frequency lower than the cutoff frequency will attenuate, rather than propagate. The following derivation assumes lossless walls. The value of c, the speed of light, should be taken to be the group velocity of light in whatever material fills the waveguide.", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 3854225, 3372377, 33125, 3372377, 3854313, 31050469, 1156215, 2924436, 164570, 28736, 12778 ], "anchor_spans": [ [ 27, 52 ], [ 119, 131 ], [ 198, 208 ], [ 235, 248 ], [ 252, 261 ], [ 302, 325 ], [ 333, 351 ], [ 405, 434 ], [ 463, 474 ], [ 692, 706 ], [ 734, 748 ] ] }, { "plaintext": "For a rectangular waveguide, the cutoff frequency is", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where are the mode numbers for the rectangle's sides of length and respectively. For TE modes, (but is not allowed), while for TM modes .", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The cutoff frequency of the TM01 mode (next higher from dominant mode TE11) in a waveguide of circular cross-section (the transverse-magnetic mode with no angular dependence and lowest radial dependence) is given by ", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where is the radius of the waveguide, and is the first root of , the Bessel function of the first kind of order 1.", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 4700 ], "anchor_spans": [ [ 72, 87 ] ] }, { "plaintext": "The dominant mode TE11 cutoff frequency is given by", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "However, the dominant mode cutoff frequency can be reduced by the introduction of baffle inside the circular cross-section waveguide. For a single-mode optical fiber, the cutoff wavelength is the wavelength at which the normalized frequency is approximately equal to 2.405.", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 41716, 21354062 ], "anchor_spans": [ [ 140, 165 ], [ 220, 240 ] ] }, { "plaintext": "The starting point is the wave equation (which is derived from the Maxwell equations),", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 19737 ], "anchor_spans": [ [ 67, 84 ] ] }, { "plaintext": "which becomes a Helmholtz equation by considering only functions of the form ", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 1156215 ], "anchor_spans": [ [ 16, 34 ] ] }, { "plaintext": "Substituting and evaluating the time derivative gives", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The function here refers to whichever field (the electric field or the magnetic field) has no vector component in the longitudinal direction - the \"transverse\" field. It is a property of all the eigenmodes of the electromagnetic waveguide that at least one of the two fields is transverse. The z axis is defined to be along the axis of the waveguide.", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The \"longitudinal\" derivative in the Laplacian can further be reduced by considering only functions of the form ", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 174706 ], "anchor_spans": [ [ 37, 46 ] ] }, { "plaintext": "where is the longitudinal wavenumber, resulting in", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 164570 ], "anchor_spans": [ [ 27, 37 ] ] }, { "plaintext": "where subscript T indicates a 2-dimensional transverse Laplacian. The final step depends on the geometry of the waveguide. The easiest geometry to solve is the rectangular waveguide. In that case, the remainder of the Laplacian can be evaluated to its characteristic equation by considering solutions of the form ", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Thus for the rectangular guide the Laplacian is evaluated, and we arrive at", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The transverse wavenumbers can be specified from the standing wave boundary conditions for a rectangular geometry cross-section with dimensions and :", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where and are the two integers representing a specific eigenmode. Performing the final substitution, we obtain", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "which is the dispersion relation in the rectangular waveguide. The cutoff frequency is the critical frequency between propagation and attenuation, which corresponds to the frequency at which the longitudinal wavenumber is zero. It is given by", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 853778 ], "anchor_spans": [ [ 13, 32 ] ] }, { "plaintext": "The wave equations are also valid below the cutoff frequency, where the longitudinal wave number is imaginary. In this case, the field decays exponentially along the waveguide axis and the wave is thus evanescent.", "section_idx": 3, "section_name": "Waveguides", "target_page_ids": [ 263902 ], "anchor_spans": [ [ 202, 212 ] ] }, { "plaintext": "Full width at half maximum", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 41200 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "High-pass filter", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 56486 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Miller effect", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 3427765 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Spatial cutoff frequency (in optical systems)", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 4573752 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Time constant", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 19770252 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Calculation of the center frequency with geometric mean and comparison to the arithmetic mean solution", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Conversion of cutoff frequency fc and time constant τ", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Mathematical definition of and information about the Bessel functions", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Filter_theory" ]

[]

[ { "plaintext": "The term data access arrangement (DAA) has the following meanings: ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In public switched telephone networks, a single item or group of items at the customer side of the network interface device for data transmission purposes, including all equipment that may affect the characteristics of the interface. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 468436, 41409, 42168 ], "anchor_spans": [ [ 3, 36 ], [ 99, 123 ], [ 128, 145 ] ] }, { "plaintext": "A data circuit-terminating equipment (DCE) supplied or approved by a common carrier that permits a DCE or data terminal equipment (DTE) to be attached to the common carrier network.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 346001, 41005, 40910, 41786, 74041 ], "anchor_spans": [ [ 7, 14 ], [ 38, 41 ], [ 69, 83 ], [ 111, 129 ], [ 131, 134 ] ] }, { "plaintext": "Data access arrangements are an integral part of all modems built for the public telephone network. In view of mixed voice and data access, DAAs are more generally referred to as direct access arrangements.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1582494, 20647197 ], "anchor_spans": [ [ 0, 11 ], [ 53, 58 ] ] }, { "plaintext": "While DAA now describes an integral component of a device that connects to the telephone network, during the 60s and 70s it described a separate device mandated by the Bell System, connected between the telephone line and non-Bell equipment, typically a modem.", "section_idx": 1, "section_name": "Requirement for DAAs", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Following the Carterfone decision, which required Bell to allow customers to attach any non-harmful equipment to their network, Bell mandated that subscribers use PCAs/DAAs - purchased exclusively from Western Electric - to ensure the network was protected. These devices were not required for Bell-provided equipment, only equipment made by independent manufacturers.", "section_idx": 1, "section_name": "Requirement for DAAs", "target_page_ids": [ 882455, 229970 ], "anchor_spans": [ [ 14, 24 ], [ 202, 218 ] ] }, { "plaintext": "At the time, some subscribers believed that the DAA was a scheme by AT&T to penalize and discourage use of non-Bell modems and recover lost profits from hardware sales, and the FCC began investigations into the legality of the practice. Subscribers also became frustrated when Bell failed to deliver DAAs in a timely fashion after the ruling, leading to the use of unauthorized third-party DAAs.", "section_idx": 1, "section_name": "Requirement for DAAs", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "There were two main varieties of DAA described by AT&T: manual and automatic. A manual DAA required a call to be initiated (or answered) as normal, at which point it could then be connected to the third-party device, while an automatic DAA allowed an attached device to be connected without human intervention, important for receiving modem use.", "section_idx": 1, "section_name": "Requirement for DAAs", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In 1975, the FCC implemented Part 68 of the FCC Rules, which granted permission for direct connection of any equipment to the telephone network given compliance with specific electrical requirements. This technically eliminated the need for DAAs, although the first modem that didn't require a separate DAA was not marketed until 1977 when a court ruled that Part 68 was legal.", "section_idx": 1, "section_name": "Requirement for DAAs", "target_page_ids": [ 41486 ], "anchor_spans": [ [ 29, 36 ] ] }, { "plaintext": " Wireline DAA - introductory slides by 3am Systems", "section_idx": 3, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Direct-Access Arrangements Are Crucial To Successful Embedded-Modem Designs - in-depth article by Jeff Sorensen", "section_idx": 3, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Local_loop" ]

[ "DAA" ]

[ { "plaintext": "In database management and information architecture, a data bank or databank is a repository of information on one or more subjects – a database – that is organized in a way that facilitates local or remote information retrieval and is able to process many continual queries over a long period of time. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8377, 185945 ], "anchor_spans": [ [ 3, 22 ], [ 27, 51 ] ] }, { "plaintext": "A data bank may also refer to an organization primarily concerned with the construction and maintenance of such a database. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A data bank may be either centralized or decentralized, though most usage of this term refers to centralized storage and retrieval of information, by way of analogy to a monetary bank. The data in a data bank can be anything from scientific information like global temperature readings, and governmental information like census statistics, to financial-system records like credit card transactions, or the inventory available from various suppliers. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 19360669, 18985040 ], "anchor_spans": [ [ 179, 183 ], [ 190, 194 ] ] }, { "plaintext": "In computing, the term databank is also obsolete (1960s through 1970s) computer jargon for database itself, and is frequently used in that sense in materials written in that period.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5213, 49607, 8377 ], "anchor_spans": [ [ 3, 12 ], [ 71, 86 ], [ 91, 99 ] ] }, { "plaintext": " Data repository", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 4855658 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " List of databases", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 67986706 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Star Wars Databank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 2371310 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Protein Data Bank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 102505 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " National Trauma Data Bank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 29113313 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Memory bank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 12232712 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " International Tree-Ring Data Bank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 39223360 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Hazardous Substances Data Bank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 24154230 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Electron microscopy data bank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 7637122 ], "anchor_spans": [ [ 1, 30 ] ] }, { "plaintext": " Dortmund Data Bank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 8248238 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Casio Databank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 8827953 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Conformational dynamics data bank", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 30357017 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Databank Systems Limited a former New Zealand banking agency", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 18811005 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": "The American Heritage Dictionary of the English Language, Fourth Edition. Houghton Mifflin, 2000.", "section_idx": 2, "section_name": "Sources", "target_page_ids": [ 255353, 1003088 ], "anchor_spans": [ [ 0, 56 ], [ 74, 90 ] ] } ]

[ "Data_management", "Information_architecture" ]

[]

[ { "plaintext": "In telecommunication, data compaction is the reduction of the number of data elements, bandwidth, cost, and time for the generation, transmission, and storage of data without loss of information by eliminating unnecessary redundancy, removing irrelevancy, or using special coding. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 40992, 15612827, 609152, 5300, 18985062, 1953582 ], "anchor_spans": [ [ 3, 20 ], [ 72, 84 ], [ 87, 96 ], [ 133, 145 ], [ 151, 166 ], [ 183, 194 ], [ 222, 232 ] ] }, { "plaintext": "Examples of data compaction methods are the use of fixed-tolerance bands, variable-tolerance bands, slope-keypoints, sample changes, curve patterns, curve fitting, variable-precision coding, frequency analysis, and probability analysis. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 522062, 29368, 555425, 1164930, 10779 ], "anchor_spans": [ [ 57, 66 ], [ 100, 105 ], [ 149, 162 ], [ 173, 182 ], [ 191, 200 ] ] }, { "plaintext": "Simply squeezing noncompacted data into a smaller space, for example by increasing packing density by transferring images from newsprint to microfilm or by transferring data on punched cards onto magnetic tape, is not data compaction.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 143202, 2842268, 24420, 20505 ], "anchor_spans": [ [ 127, 136 ], [ 140, 149 ], [ 177, 189 ], [ 196, 209 ] ] }, { "plaintext": "The use of acronyms in texting is an everyday example. The number of bits required to transmit and store \"WYSIWYG\" (What You See Is What You Get) is reduced from its expanded equivalent (7 characters vs 28). The representation of Mersenne primes is another example. The largest known is over 17 million digits long but it is represented as M57885161 in a much more compacted form.", "section_idx": 1, "section_name": "Everyday examples", "target_page_ids": [ 1052571, 305854, 33291, 18908 ], "anchor_spans": [ [ 11, 18 ], [ 23, 30 ], [ 107, 114 ], [ 232, 246 ] ] }, { "plaintext": " brevity code", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 38408129 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " commercial code (communications)", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 28739060 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " data compression", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 8013 ], "anchor_spans": [ [ 1, 17 ] ] } ]

[ "Telecommunications_techniques", "Data_compression" ]

[]

[ { "plaintext": "In metadata, the term data element is an atomic unit of data that has precise meaning or precise semantics. A data element has:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18933632 ], "anchor_spans": [ [ 3, 11 ] ] }, { "plaintext": " An identification such as a data element name", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2535572 ], "anchor_spans": [ [ 29, 46 ] ] }, { "plaintext": " A clear data element definition", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2599083 ], "anchor_spans": [ [ 9, 32 ] ] }, { "plaintext": " One or more representation terms", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2372571 ], "anchor_spans": [ [ 13, 32 ] ] }, { "plaintext": " Optional enumerated values Code (metadata)", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41250 ], "anchor_spans": [ [ 28, 43 ] ] }, { "plaintext": " A list of synonyms to data elements in other metadata registries Synonym ring", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3553110 ], "anchor_spans": [ [ 66, 78 ] ] }, { "plaintext": "Data elements usage can be discovered by inspection of software applications or application data files through a process of manual or automated Application Discovery and Understanding. Once data elements are discovered they can be registered in a metadata registry.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 454746, 3136406, 4039688, 2372015 ], "anchor_spans": [ [ 55, 75 ], [ 92, 101 ], [ 144, 183 ], [ 247, 264 ] ] }, { "plaintext": "In telecommunication, the term data element has the following components:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "A named unit of data that, in some contexts, is considered indivisible and in other contexts may consist of data items.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18985040 ], "anchor_spans": [ [ 16, 20 ] ] }, { "plaintext": "A named identifier of each of the entities and their attributes that are represented in a database.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41250, 8377 ], "anchor_spans": [ [ 8, 18 ], [ 90, 98 ] ] }, { "plaintext": "A basic unit of information built on standard structures having a unique meaning and distinct units or values.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18985062 ], "anchor_spans": [ [ 16, 27 ] ] }, { "plaintext": "In electronic record-keeping, a combination of characters or bytes referring to one separate item of information, such as name, address, or age.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 979149 ], "anchor_spans": [ [ 128, 135 ] ] }, { "plaintext": "In the areas of databases and data systems more generally a data element is a concept forming part of a data model. As an element of data representation, a collection of data elements forms a data structure.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8377, 24770596, 82871, 8519 ], "anchor_spans": [ [ 16, 25 ], [ 30, 42 ], [ 104, 114 ], [ 192, 206 ] ] }, { "plaintext": "In practice, data elements (fields, columns, attributes, etc.) are sometimes \"overloaded\", meaning a given data element will have multiple potential meanings. While a known bad practice, overloading is nevertheless a very real factor or barrier to understanding what a system is doing.", "section_idx": 1, "section_name": "In practice", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Application Discovery and Understanding", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 4039688 ], "anchor_spans": [ [ 1, 40 ] ] }, { "plaintext": " Data element definition", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 2599083 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Data dictionary", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 645139 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Data hierarchy", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 998835 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " ISO/IEC 11179 metadata registry specification", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 2372128 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Metadata", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 18933632 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Representation term", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 2372571 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Universal Data Element Framework", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 2570284 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Data collection system", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 52272502 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Association for Enterprise Integration", "section_idx": 4, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Federal XML Developer's Guide", "section_idx": 4, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ISO/IEC 11179 Standards (see ISO/IEC 11179-3:2003 clause 3.3.36)", "section_idx": 4, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Metadata", "Enterprise_application_integration" ]

[ "unit of data" ]

[ { "plaintext": "In telecommunications, a data forwarder is a device that ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "(a) receives data from one data link and retransmits data representing the same information, using proper format and link protocols, to another data link.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18985040, 40996, 18985062, 7428842 ], "anchor_spans": [ [ 13, 17 ], [ 27, 36 ], [ 80, 91 ], [ 106, 112 ] ] }, { "plaintext": "and ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "(b) may forward data between ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "(a) links that are identical, i.e., TADIL B to TADIL B, ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "(b) links that are similar, i.e., TADIL A to TADIL B, or ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2238415 ], "anchor_spans": [ [ 34, 41 ] ] }, { "plaintext": "(c) links that are dissimilar, i.e., TADIL A to TADIL J.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2238415, 1490972 ], "anchor_spans": [ [ 37, 44 ], [ 48, 55 ] ] } ]

[ "Telecommunications_equipment" ]

[]

[ { "plaintext": "A datagram is a basic transfer unit associated with a packet-switched network. Datagrams are typically structured in header and payload sections. Datagrams provide a connectionless communication service across a packet-switched network. The delivery, arrival time, and order of arrival of datagrams need not be guaranteed by the network.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 43339, 472401, 15160666, 40950 ], "anchor_spans": [ [ 54, 77 ], [ 117, 123 ], [ 128, 135 ], [ 166, 194 ] ] }, { "plaintext": "In the early 1970s, the term datagram was created by combining the words data and telegram by the CCITT rapporteur on packet switching, Halvor Bothner-By.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 14744, 65353050 ], "anchor_spans": [ [ 98, 103 ], [ 136, 153 ] ] }, { "plaintext": "While the word was new, the concept had already a long history.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In 1962, Paul Baran described, in a RAND Corporation report, a hypothetical military network having to resist a nuclear attack. Small standardized \"message blocks\", bearing source and destination addresses, were stored and forwarded in computer nodes of a highly redundant meshed computer network. \"The network user who has called up a \"virtual connection\" to an end station and has transmitted messages ... might also view the system as a black box providing an apparent circuit connection\".", "section_idx": 1, "section_name": "History", "target_page_ids": [ 1016348, 23712727, 604831 ], "anchor_spans": [ [ 9, 19 ], [ 36, 52 ], [ 212, 232 ] ] }, { "plaintext": "In 1967, Donald Davies published a seminal article in which he introduced the now largely used words packet and packet switching. ", "section_idx": 1, "section_name": "History", "target_page_ids": [ 675311, 43734, 43339 ], "anchor_spans": [ [ 9, 22 ], [ 101, 107 ], [ 112, 128 ] ] }, { "plaintext": "His core network is similar to that of Paul Baran although it has been independently designed. To deal with datagram permutations (due to dynamically updated routing preferences) and to datagram losses (unavoidable when fast sources send to a slow destinations), he assumes that \"all users of the network will provide themselves with some kind of error control\" (what will be called later on a pure datagram service). His target is, for the first time in packet switching, a \"common-carrier communication network\". To support remote access to computer services by user terminals, which at that time transmitted in general character by character, he included at the network periphery interface computers that convert character flows into packet flows and conversely. ", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In 1970, Lawrence Roberts and Barry D. Wessler published an article about ARPANET, the first multi-node packet-switching network. An accompanying paper described its switching nodes (the IMPs) and its packet formats. The network core performed datagram switching as in Baran's and Davies' model, but provision was added within the network, at its periphery, to deal with datagram losses and permutations. A reliable message transfer service was thus offered to user computers, thus greatly simplifying their own work, and keeping it less dependent on further research.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 253111 ], "anchor_spans": [ [ 74, 81 ] ] }, { "plaintext": "In 1973, Louis Pouzin presented his design for Cyclades, the first real size network implementing the pure datagram model of Donald Davies.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 2417294, 1760074 ], "anchor_spans": [ [ 9, 21 ], [ 47, 55 ] ] }, { "plaintext": "The Cyclades team has thus been first to tackle the highly complex problem of providing to user applications a reliable virtual circuit service (the equivalent of an Internet TCP connection) while using an end to end network service known to possibly produce non negligible datagram losses and permutations. ", "section_idx": 1, "section_name": "History", "target_page_ids": [ 30538 ], "anchor_spans": [ [ 175, 178 ] ] }, { "plaintext": "Although Pouzin's concern \"in a first stage is not to make breakthrough in packet switching technology, but to build a reliable communications tool for Cyclades\", two members of his team, Hubert Zimmerman and Gérard Le Lann, made significant contributions to the design of Internet's TCP that Vint Cerf, its main designer, acknowledged.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 2561429, 65407219, 32433 ], "anchor_spans": [ [ 188, 204 ], [ 209, 223 ], [ 293, 302 ] ] }, { "plaintext": "In 1981, the Defense Advanced Research Projects Agency (DARPA) issued the first specification the Internet protocol (IP). It introduced a major evolution of the datagram concept: fragmentation. ", "section_idx": 1, "section_name": "History", "target_page_ids": [ 8957, 15323, 323677 ], "anchor_spans": [ [ 56, 61 ], [ 98, 115 ], [ 179, 192 ] ] }, { "plaintext": "With fragmentation, some parts of the global network may use large packet size (typically local area networks for processing power minimization), while some others may impose smaller packet sizes (typically wide area networks for response time minimization). Network nodes may split a packet of a datagram into several smaller packets of the same datagram.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 17739, 38140 ], "anchor_spans": [ [ 90, 108 ], [ 207, 224 ] ] }, { "plaintext": "In 1999, the Internet Engineering Task Force (IETF) officialised the use of the already largely deployed Network address translation (NAT)", "section_idx": 1, "section_name": "History", "target_page_ids": [ 15285, 53036 ], "anchor_spans": [ [ 13, 44 ], [ 105, 132 ] ] }, { "plaintext": "whereby each public address can be shared by several private devices. With it, the forthcoming Internet Address exhaustion was delayed, leaving enough time to introduce IPv6, the new generation of Internet packets supporting longer addresses. The initial principle of full end to end network transparency to datagrams was for this relaxed: NAT nodes had to manage per-connection states, making them in part connection oriented.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 6852935, 15318, 238042, 2137712 ], "anchor_spans": [ [ 95, 122 ], [ 169, 173 ], [ 273, 283 ], [ 407, 426 ] ] }, { "plaintext": "In 2015, the IETF upgraded its weak \"informational\" recommendation of 1998, that datagram switching nodes perform active queue management (AQM), to make it a stronger and more detailed \"best current practice\" recommendation. ", "section_idx": 1, "section_name": "History", "target_page_ids": [ 15285, 5361236, 8629620 ], "anchor_spans": [ [ 13, 17 ], [ 114, 137 ], [ 187, 208 ] ] }, { "plaintext": "While the initial datagram queueing model was simple to implement and needed no more tuning than queue lengths, support of more sophisticated and parametrized mechanisms were found necessary \"to improve and preserve Internet performance\" (RED, ECN etc.). Further research on the subject was also called for, with a list of identified items.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 1112827, 309470 ], "anchor_spans": [ [ 239, 242 ], [ 244, 247 ] ] }, { "plaintext": "RFC 1594 defines the term Datagram as follows:", "section_idx": 2, "section_name": "Definition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A datagram needs to be self-contained without reliance on earlier exchanges because there is no connection of fixed duration between the two communicating points as there is, for example, in most voice telephone conversations.", "section_idx": 2, "section_name": "Definition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Datagram service is often compared to a mail delivery service; the user only provides the destination address, but receives no guarantee of delivery, and no confirmation upon successful delivery. Datagram service is therefore considered unreliable. Datagram service routes datagrams without first creating a predetermined path. Datagram service is therefore considered connectionless. There is also no consideration given to the order in which it and other datagrams are sent or received. In fact, many datagrams in the same group can travel along different paths before reaching the same destination.", "section_idx": 2, "section_name": "Definition", "target_page_ids": [ 2563492, 40950 ], "anchor_spans": [ [ 237, 247 ], [ 369, 383 ] ] }, { "plaintext": "Each datagram has two components, a header and a data payload. The header contains all the information sufficient for routing from the originating equipment to the destination without relying on prior exchanges between the equipment and the network. Headers may include source and destination addresses as well as a type field. The payload is the data to be transported. This process of nesting data payloads in a tagged header is called encapsulation.", "section_idx": 3, "section_name": "Structure", "target_page_ids": [ 472401, 15160666, 4269641 ], "anchor_spans": [ [ 36, 42 ], [ 55, 62 ], [ 440, 453 ] ] }, { "plaintext": "The Internet Protocol (IP) defines standards for several types of datagrams. The internet layer is a datagram service provided by an IP. For example, UDP is run by a datagram service on the internet layer. IP is an entirely connectionless, best effort, unreliable, message delivery service. TCP is a higher level protocol running on top of IP that provides a reliable connection-oriented service.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [ 15323, 11207736, 31929, 30538 ], "anchor_spans": [ [ 4, 21 ], [ 81, 95 ], [ 150, 153 ], [ 291, 294 ] ] }, { "plaintext": " Datagram socket", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 4764218 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Frame (networking)", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 41172 ], "anchor_spans": [ [ 1, 19 ] ] } ]

[ "Units_of_information", "Packets_(information_technology)" ]

[]

[ { "plaintext": "Data integrity is the maintenance of, and the assurance of, data accuracy and consistency over its entire life-cycle and is a critical aspect to the design, implementation, and usage of any system that stores, processes, or retrieves data. The term is broad in scope and may have widely different meanings depending on the specific context even under the same general umbrella of computing. It is at times used as a proxy term for data quality, while data validation is a prerequisite for data integrity.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3331083, 5213, 1609808, 1705399 ], "anchor_spans": [ [ 106, 116 ], [ 380, 389 ], [ 431, 443 ], [ 451, 466 ] ] }, { "plaintext": "Data integrity is the opposite of data corruption. The overall intent of any data integrity technique is the same: ensure data is recorded exactly as intended (such as a database correctly rejecting mutually exclusive possibilities). Moreover, upon later retrieval, ensure the data is the same as when it was originally recorded. In short, data integrity aims to prevent unintentional changes to information. Data integrity is not to be confused with data security, the discipline of protecting data from unauthorized parties.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1040512, 28688670, 1157832 ], "anchor_spans": [ [ 34, 49 ], [ 255, 264 ], [ 451, 464 ] ] }, { "plaintext": "Any unintended changes to data as the result of a storage, retrieval or processing operation, including malicious intent, unexpected hardware failure, and human error, is failure of data integrity. If the changes are the result of unauthorized access, it may also be a failure of data security. Depending on the data involved this could manifest itself as benign as a single pixel in an image appearing a different color than was originally recorded, to the loss of vacation pictures or a business-critical database, to even catastrophic loss of human life in a life-critical system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 4584639, 286550 ], "anchor_spans": [ [ 155, 166 ], [ 562, 582 ] ] }, { "plaintext": "Physical integrity deals with challenges which are associated with correctly storing and fetching the data itself. Challenges with physical integrity may include electromechanical faults, design flaws, material fatigue, corrosion, power outages, natural disasters, and other special environmental hazards such as ionizing radiation, extreme temperatures, pressures and g-forces. Ensuring physical integrity includes methods such as redundant hardware, an uninterruptible power supply, certain types of RAID arrays, radiation hardened chips, error-correcting memory, use of a clustered file system, using file systems that employ block level checksums such as ZFS, storage arrays that compute parity calculations such as exclusive or or use a cryptographic hash function and even having a watchdog timer on critical subsystems.", "section_idx": 1, "section_name": "Integrity types", "target_page_ids": [ 31322120, 348898, 155443, 296636, 202522, 389836, 1953581, 41834, 54695, 1041641, 4473248, 10459749, 7538, 57282698, 105979, 439526, 862179 ], "anchor_spans": [ [ 162, 179 ], [ 211, 218 ], [ 220, 229 ], [ 231, 244 ], [ 313, 331 ], [ 369, 376 ], [ 432, 441 ], [ 455, 483 ], [ 502, 506 ], [ 515, 533 ], [ 541, 564 ], [ 575, 596 ], [ 641, 649 ], [ 659, 662 ], [ 720, 732 ], [ 742, 769 ], [ 788, 802 ] ] }, { "plaintext": "Physical integrity often makes extensive use of error detecting algorithms known as error-correcting codes. Human-induced data integrity errors are often detected through the use of simpler checks and algorithms, such as the Damm algorithm or Luhn algorithm. These are used to maintain data integrity after manual transcription from one computer system to another by a human intermediary (e.g. credit card or bank routing numbers). Computer-induced transcription errors can be detected through hash functions.", "section_idx": 1, "section_name": "Integrity types", "target_page_ids": [ 4237207, 37957721, 582440, 13790 ], "anchor_spans": [ [ 84, 106 ], [ 225, 239 ], [ 243, 257 ], [ 494, 508 ] ] }, { "plaintext": "In production systems, these techniques are used together to ensure various degrees of data integrity. For example, a computer file system may be configured on a fault-tolerant RAID array, but might not provide block-level checksums to detect and prevent silent data corruption. As another example, a database management system might be compliant with the ACID properties, but the RAID controller or hard disk drive's internal write cache might not be.", "section_idx": 1, "section_name": "Integrity types", "target_page_ids": [ 1010280, 1040512, 60776 ], "anchor_spans": [ [ 127, 138 ], [ 255, 277 ], [ 356, 360 ] ] }, { "plaintext": "This type of integrity is concerned with the correctness or rationality of a piece of data, given a particular context. This includes topics such as referential integrity and entity integrity in a relational database or correctly ignoring impossible sensor data in robotic systems. These concerns involve ensuring that the data \"makes sense\" given its environment. Challenges include software bugs, design flaws, and human errors. Common methods of ensuring logical integrity include things such as check constraints, foreign key constraints, program assertions, and other run-time sanity checks.", "section_idx": 1, "section_name": "Integrity types", "target_page_ids": [ 357339, 61032, 445718, 946798, 25873, 37085, 3450233, 259065, 234018 ], "anchor_spans": [ [ 45, 56 ], [ 60, 71 ], [ 149, 170 ], [ 175, 191 ], [ 197, 216 ], [ 384, 397 ], [ 499, 515 ], [ 518, 540 ], [ 551, 560 ] ] }, { "plaintext": "Both physical and logical integrity often share many common challenges such as human errors and design flaws, and both must appropriately deal with concurrent requests to record and retrieve data, the latter of which is entirely a subject on its own.", "section_idx": 1, "section_name": "Integrity types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "If a data sector only has a logical error, it can be reused by overwriting it with new data. In case of a physical error, the affected data sector is permanently unusable.", "section_idx": 1, "section_name": "Integrity types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Data integrity contains guidelines for data retention, specifying or guaranteeing the length of time data can be retained in a particular database. To achieve data integrity, these rules are consistently and routinely applied to all data entering the system, and any relaxation of enforcement could cause errors in the data. Implementing checks on the data as close as possible to the source of input (such as human data entry), causes less erroneous data to enter the system. Strict enforcement of data integrity rules results in lower error rates, and time saved troubleshooting and tracing erroneous data and the errors it causes to algorithms.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [ 3095080 ], "anchor_spans": [ [ 39, 53 ] ] }, { "plaintext": "Data integrity also includes rules defining the relations a piece of data can have to other pieces of data, such as a Customer record being allowed to link to purchased Products, but not to unrelated data such as Corporate Assets. Data integrity often includes checks and correction for invalid data, based on a fixed schema or a predefined set of rules. An example being textual data entered where a date-time value is required. Rules for data derivation are also applicable, specifying how a data value is derived based on algorithm, contributors and conditions. It also specifies the conditions on how the data value could be re-derived.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [ 345937 ], "anchor_spans": [ [ 318, 324 ] ] }, { "plaintext": "Data integrity is normally enforced in a database system by a series of integrity constraints or rules. Three types of integrity constraints are an inherent part of the relational data model: entity integrity, referential integrity and domain integrity.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [ 8377 ], "anchor_spans": [ [ 41, 56 ] ] }, { "plaintext": " Entity integrity concerns the concept of a primary key. Entity integrity is an integrity rule which states that every table must have a primary key and that the column or columns chosen to be the primary key should be unique and not null.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [ 946798, 259056 ], "anchor_spans": [ [ 1, 17 ], [ 44, 55 ] ] }, { "plaintext": " Referential integrity concerns the concept of a foreign key. The referential integrity rule states that any foreign-key value can only be in one of two states. The usual state of affairs is that the foreign-key value refers to a primary key value of some table in the database. Occasionally, and this will depend on the rules of the data owner, a foreign-key value can be null. In this case, we are explicitly saying that either there is no relationship between the objects represented in the database or that this relationship is unknown.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [ 445718, 259065, 2002540 ], "anchor_spans": [ [ 1, 22 ], [ 49, 60 ], [ 373, 377 ] ] }, { "plaintext": " Domain integrity specifies that all columns in a relational database must be declared upon a defined domain. The primary unit of data in the relational data model is the data item. Such data items are said to be non-decomposable or atomic. A domain is a set of values of the same type. Domains are therefore pools of values from which actual values appearing in the columns of a table are drawn.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " User-defined integrity refers to a set of rules specified by a user, which do not belong to the entity, domain and referential integrity categories.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "If a database supports these features, it is the responsibility of the database to ensure data integrity as well as the consistency model for the data storage and retrieval. If a database does not support these features, it is the responsibility of the applications to ensure data integrity while the database supports the consistency model for the data storage and retrieval.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [ 274522, 274522 ], "anchor_spans": [ [ 120, 137 ], [ 323, 340 ] ] }, { "plaintext": "Having a single, well-controlled, and well-defined data-integrity system increases", "section_idx": 2, "section_name": "Databases", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " stability (one centralized system performs all data integrity operations)", "section_idx": 2, "section_name": "Databases", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " performance (all data integrity operations are performed in the same tier as the consistency model)", "section_idx": 2, "section_name": "Databases", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " re-usability (all applications benefit from a single centralized data integrity system)", "section_idx": 2, "section_name": "Databases", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " maintainability (one centralized system for all data integrity administration).", "section_idx": 2, "section_name": "Databases", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Modern databases support these features (see Comparison of relational database management systems), and it has become the de facto responsibility of the database to ensure data integrity. Companies, and indeed many database systems, offer products and services to migrate legacy systems to modern databases.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [ 8377, 1569036 ], "anchor_spans": [ [ 7, 15 ], [ 45, 97 ] ] }, { "plaintext": "An example of a data-integrity mechanism is the parent-and-child relationship of related records. If a parent record owns one or more related child records all of the referential integrity processes are handled by the database itself, which automatically ensures the accuracy and integrity of the data so that no child record can exist without a parent (also called being orphaned) and that no parent loses their child records. It also ensures that no parent record can be deleted while the parent record owns any child records. All of this is handled at the database level and does not require coding integrity checks into each application.", "section_idx": 2, "section_name": "Databases", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Various research results show that neither widespread filesystems (including UFS, Ext, XFS, JFS and NTFS) nor hardware RAID solutions provide sufficient protection against data integrity problems.", "section_idx": 3, "section_name": "File systems", "target_page_ids": [ 1010280, 250992, 986581, 34203, 50487, 39184, 54695 ], "anchor_spans": [ [ 54, 64 ], [ 77, 80 ], [ 82, 85 ], [ 87, 90 ], [ 92, 95 ], [ 100, 104 ], [ 110, 123 ] ] }, { "plaintext": "Some filesystems (including Btrfs and ZFS) provide internal data and metadata checksumming that is used for detecting silent data corruption and improving data integrity. If a corruption is detected that way and internal RAID mechanisms provided by those filesystems are also used, such filesystems can additionally reconstruct corrupted data in a transparent way. This approach allows improved data integrity protection covering the entire data paths, which is usually known as end-to-end data protection.", "section_idx": 3, "section_name": "File systems", "target_page_ids": [ 12214168, 57282698, 18933632, 1040512, 1040512 ], "anchor_spans": [ [ 28, 33 ], [ 38, 41 ], [ 69, 77 ], [ 118, 140 ], [ 481, 507 ] ] }, { "plaintext": " The U.S. Food and Drug Administration has created draft guidance on data integrity for the pharmaceutical manufacturers required to adhere to U.S. Code of Federal Regulations 21 CFR Parts 210–212. Outside the U.S., similar data integrity guidance has been issued by the United Kingdom (2015), Switzerland (2016), and Australia (2017).", "section_idx": 4, "section_name": "Data integrity as applied to various industries", "target_page_ids": [ 11632 ], "anchor_spans": [ [ 10, 38 ] ] }, { "plaintext": " Various standards for the manufacture of medical devices address data integrity either directly or indirectly, including ISO 13485, ISO 14155, and ISO 5840.", "section_idx": 4, "section_name": "Data integrity as applied to various industries", "target_page_ids": [ 6410435, 32136834 ], "anchor_spans": [ [ 122, 131 ], [ 133, 142 ] ] }, { "plaintext": " In early 2017, the Financial Industry Regulatory Authority (FINRA), noting data integrity problems with automated trading and money movement surveillance systems, stated it would make \"the development of a data integrity program to monitor the accuracy of the submitted data\" a priority. In early 2018, FINRA said it would expand its approach on data integrity to firms' \"technology change management policies and procedures\" and Treasury securities reviews.", "section_idx": 4, "section_name": "Data integrity as applied to various industries", "target_page_ids": [ 12481308 ], "anchor_spans": [ [ 20, 59 ] ] }, { "plaintext": " Other sectors such as mining and product manufacturing are increasingly focusing on the importance of data integrity in associated automation and production monitoring assets.", "section_idx": 4, "section_name": "Data integrity as applied to various industries", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Cloud storage providers have long faced significant challenges ensuring the integrity or provenance of customer data and tracking violations.", "section_idx": 4, "section_name": "Data integrity as applied to various industries", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " End-to-end data integrity", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 1040512 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Message authentication", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 46671693 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " National Information Systems Security Glossary", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 1011395 ], "anchor_spans": [ [ 1, 47 ] ] }, { "plaintext": " Single version of the truth", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 8658994 ], "anchor_spans": [ [ 1, 28 ] ] } ]

[ "Data_quality", "Transaction_processing" ]

[ "integrity", "fixity" ]

[ { "plaintext": "A data link is the means of connecting one location to another for the purpose of transmitting and receiving digital information (data communication). It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver (two pieces of data terminal equipment) and the interconnecting data telecommunication circuit. These are governed by a link protocol enabling digital data to be transferred from a data source to a data sink.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41837, 42168, 74041, 346001, 30862590, 5040275 ], "anchor_spans": [ [ 28, 62 ], [ 130, 148 ], [ 263, 286 ], [ 317, 342 ], [ 368, 381 ], [ 446, 455 ] ] }, { "plaintext": "There are at least three types of basic data-link configurations that can be conceived of and used:", "section_idx": 1, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Simplex communications, most commonly meaning all communications in one direction only.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 663969 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Half-duplex communications, meaning communications in both directions, but not both ways simultaneously.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 2112491 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Duplex communications, communications in both directions simultaneously.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 2112491 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": "In civil aviation, a data-link system (known as Controller Pilot Data Link Communications) is used to send information between aircraft and air traffic controllers for example when an aircraft is too far from the ATC to make voice radio communication and radar observations possible. Such systems are used for aircraft crossing the Atlantic and Pacific oceans. One such system, used by Nav Canada and NATS over the North Atlantic, uses a five-digit data link sequence number confirmed between air traffic control and the pilots of the aircraft before the aircraft proceeds to cross the ocean. This system uses the aircraft's flight management computer to send location, speed and altitude information about the aircraft to the ATC. ATC can then send messages to the aircraft regarding any necessary change of course. ", "section_idx": 2, "section_name": "Aviation", "target_page_ids": [ 58422, 7896257, 48563, 25676, 698, 23070, 1206450, 423831, 2490859 ], "anchor_spans": [ [ 9, 17 ], [ 48, 89 ], [ 140, 159 ], [ 255, 260 ], [ 332, 340 ], [ 345, 352 ], [ 386, 396 ], [ 401, 405 ], [ 625, 651 ] ] }, { "plaintext": "In unmanned aircraft, land vehicles, boats, and spacecraft, a two-way (full-duplex or half-duplex) data-link is used to send control signals, and to receive telemetry.", "section_idx": 2, "section_name": "Aviation", "target_page_ids": [ 58900, 2112491, 2112491, 275473, 46256 ], "anchor_spans": [ [ 3, 20 ], [ 71, 82 ], [ 86, 97 ], [ 125, 140 ], [ 157, 166 ] ] }, { "plaintext": " ACARS", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2293875 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " Deep Space Network", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 231522 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Space probe", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 10204411 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Tactical Data Links", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 15487076 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Terminal (telecommunication)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 460792 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Timex Datalink", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 9015451 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Unmanned Aircraft System", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 58900 ], "anchor_spans": [ [ 1, 25 ] ] } ]

[ "Data_transmission" ]

[]

[ { "plaintext": "A data service unit, sometimes called a digital service unit, is a piece of telecommunications circuit terminating equipment that transforms digital data between telephone company lines and local equipment. The device converts bipolar digital signals coming ultimately from a digital circuit and directly from a Channel service unit (CSU), into a format (e.g. RS- 530) compatible with the piece of data terminal equipment (DTE) (e.g. a router) to which the data is sent. The DSU also performs a similar process in reverse for data heading from the DTE toward the circuit. The telecommunications service a DSU supports can be a point-to-point or multipoint operation in a digital data network.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 40792, 40863, 74041, 8276 ], "anchor_spans": [ [ 76, 93 ], [ 227, 250 ], [ 312, 332 ], [ 398, 421 ], [ 671, 683 ] ] }, { "plaintext": "A DSU is a two or more port device; one port is called the WAN (wide area network) port and the other is called a DTE port. The purpose of the DSU is to transfer serial data synchronously between the WAN port and the DTE ports. If more than one DTE port is used, the DSU assigns the DTE data according to time slots (channels) on the WAN side.", "section_idx": 1, "section_name": "Form and purpose", "target_page_ids": [ 38140 ], "anchor_spans": [ [ 64, 81 ] ] }, { "plaintext": "On the WAN side, the DSU, via a CSU, interfaces with a digital carrier such as DS1 or DS3 or a low speed Digital Data Service. On the DTE side, the DSU provides control lines, timing lines and appropriate physical and electrical interface. To maintain the synchronous relationship between the ports, the DSU manages timing by slaving ports to the bit rate of another or to its internal clock. Typically, the DTE port provides timing to the data terminal equipment while the WAN port dictates the rate.", "section_idx": 1, "section_name": "Form and purpose", "target_page_ids": [ 907542, 1219567 ], "anchor_spans": [ [ 79, 82 ], [ 86, 89 ] ] }, { "plaintext": "DSUs usually include some maintenance capabilities. At minimum, they can loop data back at either the WAN or DTE ports, or at both. When only one port is looped back, the data received at that port is simultaneously sent back toward the port and passed in normal fashion to the other port. Most DSUs also allow various data patterns to be generated and monitored to measure error rate of the communication link. A DSU may be a separate piece of equipment, or may be combined in a CSU/DSU.", "section_idx": 1, "section_name": "Form and purpose", "target_page_ids": [ 923209 ], "anchor_spans": [ [ 481, 488 ] ] } ]

[ "Telecommunications_equipment" ]

[ "DSU" ]

[ { "plaintext": "In telecommunication, data signaling rate (DSR), also known as gross bit rate, is the aggregate rate at which data passes a point in the transmission path of a data transmission system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 272290, 18985040, 609152, 40996, 46982 ], "anchor_spans": [ [ 3, 20 ], [ 63, 77 ], [ 110, 114 ], [ 137, 149 ], [ 150, 154 ], [ 165, 184 ] ] }, { "plaintext": " The DSR is usually expressed in bits per second.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 272290 ], "anchor_spans": [ [ 33, 48 ] ] }, { "plaintext": " The data signaling rate is given by where m is the number of parallel channels, ni is the number of significant conditions of the modulation in the i-th channel, and Ti is the unit interval, expressed in seconds, for the i-th channel.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 275871, 20637, 156700, 2078753 ], "anchor_spans": [ [ 10, 19 ], [ 132, 142 ], [ 155, 162 ], [ 178, 191 ] ] }, { "plaintext": " For serial transmission in a single channel, the DSR reduces to (1/T)log2n; with a two-condition modulation, i. e. n = 2, the DSR is 1/T, according to Hartley's law.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 194114, 71085 ], "anchor_spans": [ [ 5, 24 ], [ 152, 165 ] ] }, { "plaintext": " For parallel transmission with equal unit intervals and equal numbers of significant conditions on each channel, the DSR is (m/T)log2n; in the case of a two-condition modulation, this reduces to m/T.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 882939, 20637 ], "anchor_spans": [ [ 5, 26 ], [ 168, 178 ] ] }, { "plaintext": " The DSR may be expressed in bauds, in which case, the factor log2ni in the above summation formula should be deleted when calculating bauds.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40688 ], "anchor_spans": [ [ 29, 33 ] ] }, { "plaintext": " In synchronous binary signaling, the DSR in bits per second may be numerically the same as the modulation rate expressed in bauds. Signal processors, such as four-phase modems, cannot change the DSR, but the modulation rate depends on the line modulation scheme, in accordance with Note 4. For example, in a 2400 bit/s 4-phase sending modem, the signaling rate is 2400 bit/s on the serial input side, but the modulation rate is only 1200 bauds on the 4-phase output side.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 238686, 275871, 272290, 2518170, 275871, 24047, 946963, 20647197, 194114 ], "anchor_spans": [ [ 16, 22 ], [ 23, 32 ], [ 45, 60 ], [ 96, 111 ], [ 132, 138 ], [ 164, 169 ], [ 240, 244 ], [ 336, 341 ], [ 383, 389 ] ] }, { "plaintext": "The maximum user signaling rate, synonymous to gross bit rate or data signaling rate, is the maximum rate, in bits per second, at which binary information can be transferred in a given direction between users over the telecommunications system facilities dedicated to a particular information transfer transaction, under conditions of continuous transmission and no overhead information.", "section_idx": 1, "section_name": "Maximum rate", "target_page_ids": [ 272290, 272290, 238686, 18985062, 40925, 47867, 609152, 41476 ], "anchor_spans": [ [ 47, 61 ], [ 110, 125 ], [ 136, 142 ], [ 143, 154 ], [ 218, 243 ], [ 281, 301 ], [ 346, 358 ], [ 366, 386 ] ] }, { "plaintext": "For a single channel, the signaling rate is given by , where SCSR is the single-channel signaling rate in bits per second, T is the minimum time interval in seconds for which each level must be maintained, and n is the number of significant conditions of modulation of the channel.", "section_idx": 1, "section_name": "Maximum rate", "target_page_ids": [ 41703, 30012, 20637 ], "anchor_spans": [ [ 26, 35 ], [ 140, 144 ], [ 255, 265 ] ] }, { "plaintext": "In the case where an individual end-to-end telecommunications service is provided by parallel channels, the parallel-channel signaling rate is given by , where PCSR is the total signaling rate for m channels, m is the number of parallel channels, Ti is the minimum interval between significant instants for the I-th channel, and ni is the number of significant conditions of modulation for the I-th channel.", "section_idx": 1, "section_name": "Maximum rate", "target_page_ids": [ 41782, 41703, 20637 ], "anchor_spans": [ [ 43, 69 ], [ 178, 187 ], [ 375, 385 ] ] }, { "plaintext": "In the case where an end-to-end telecommunications service is provided by tandem channels, the end-to-end signaling rate is the lowest signaling rate among the component channels.", "section_idx": 1, "section_name": "Maximum rate", "target_page_ids": [ 41782, 677931 ], "anchor_spans": [ [ 32, 58 ], [ 74, 80 ] ] }, { "plaintext": " Bit rate", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 272290 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Bandwidth (computing)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 15612827 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Baud", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 40688 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": " Line rate", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 272290 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Transfer rate", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 272290 ], "anchor_spans": [ [ 1, 14 ] ] } ]

[ "Data_transmission", "Temporal_rates" ]

[ "data signalling rate", "equivalent bit rate", "equivalent binary digit rate", "equivalent binary transfer rate", "DSR" ]

[ { "plaintext": "In telecommunication, a data transmission circuit is the transmission media and the intervening equipment used for the data transfer between data terminal equipment (DTEs). ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 41812, 42168, 460792, 74041 ], "anchor_spans": [ [ 3, 20 ], [ 57, 75 ], [ 119, 132 ], [ 146, 154 ], [ 166, 170 ] ] }, { "plaintext": "A data transmission circuit includes any required signal conversion equipment. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42168, 346001, 41703 ], "anchor_spans": [ [ 2, 19 ], [ 20, 27 ], [ 50, 56 ] ] }, { "plaintext": "A data transmission circuit may transfer information in (a) one direction only, (b) either direction but one way at a time, or (c) both directions simultaneously. See duplex (telecommunications).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18985062, 2112491 ], "anchor_spans": [ [ 41, 52 ], [ 168, 195 ] ] }, { "plaintext": " Telecommunication circuit", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 346001 ], "anchor_spans": [ [ 1, 26 ] ] } ]

[ "Data_transmission" ]

[]

[ { "plaintext": "In communications messages, a date-time group (DTG) is a set of characters, usually in a prescribed format, used to express the year, the month, the day of the month, the hour of the day, the minute of the hour, and the time zone, if different from Coordinated Universal Time (UTC). The order in which these elements are presented may vary. The DTG is usually placed in the header of the message. One example is \" (UTC)\"; while another example is \"\".", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 30890, 25453500, 472401 ], "anchor_spans": [ [ 220, 229 ], [ 249, 275 ], [ 374, 380 ] ] }, { "plaintext": "The DTG may indicate either the date and time a message was dispatched by a transmitting station or the date and time it was handed into a transmission facility by a user or originator for dispatch.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 7123, 609152, 41132, 2052479 ], "anchor_spans": [ [ 32, 36 ], [ 139, 151 ], [ 152, 160 ], [ 166, 170 ] ] }, { "plaintext": "The DTG may be used as a message identifier if it is unique for each message.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41250 ], "anchor_spans": [ [ 33, 43 ] ] }, { "plaintext": "A form of DTG is used in the US Military's message traffic (a form of Automated Message Handling System). In US military messages and communications (e.g., on maps showing troop movements) the format is DD HHMM (SS) Z MON YY. Although occasionally seen with spaces, it can also be written as a single string of characters. Three different formats can be found:", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 32212, 1025345, 1538135 ], "anchor_spans": [ [ 29, 40 ], [ 43, 58 ], [ 70, 103 ] ] }, { "plaintext": " - Full time (used for software timestamps)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " - shortened time (used e.g. for timestamps manually written)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " - short time (e.g. used for planning)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " references the military identifier of time zone:", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " UTC-12: Y (e.g., Fiji)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC-11: X (American Samoa)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC-10: W (Honolulu, HI)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC-9: V (Juneau, AK)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC-8: U (PST, Los Angeles, CA)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500, 524024 ], "anchor_spans": [ [ 1, 4 ], [ 11, 14 ] ] }, { "plaintext": " UTC-7: T (MST, Denver, CO)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500, 496077 ], "anchor_spans": [ [ 1, 4 ], [ 11, 14 ] ] }, { "plaintext": " UTC-6: S (CST, Dallas, TX)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500, 481638 ], "anchor_spans": [ [ 1, 4 ], [ 11, 14 ] ] }, { "plaintext": " UTC-5: R (EST, New York, NY)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500, 496028 ], "anchor_spans": [ [ 1, 4 ], [ 11, 14 ] ] }, { "plaintext": " UTC-4: Q (Halifax, Nova Scotia)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC-3: P (Buenos Aires, Argentina)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC-2: O (Godthab, Greenland)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC-1: N (Azores)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+-0: Z (Zulu time)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500, 25453500 ], "anchor_spans": [ [ 1, 4 ], [ 12, 21 ] ] }, { "plaintext": " UTC+1: A (France)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+2: B (Athens, Greece)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+3: C (Arab Standard Time, Iraq, Bahrain, Kuwait, Saudi Arabia, Yemen, Qatar)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+4: D (Used for Moscow, Russia, and Afghanistan, however, Afghanistan is technically +4:30 from UTC)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+5: E (Pakistan, Kazakhstan, Tajikistan, Uzbekistan, and Turkmenistan)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+6: F (Bangladesh)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+7: G (Thailand)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+8: H (Beijing, China)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+9: I (Tokyo, Japan)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+10: K (Brisbane, Australia)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+11: L (Sydney, Australia)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " UTC+12: M (Wellington, New Zealand)", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [ 25453500 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": "Example 1: represents the 5th day of the current month 11:00 (UTC).", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Example 2: represents 09th July 2011 4:30 pm (MST).", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Example 3: represents the current time of refresh: (UTC).", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "“Zulu time” does not mean “local time” unless a Zulu time zone is specified. Earth rotates in 24 hours, thus there are 24 hours in a day. The English alphabet has 26 letters; J is local time, and the other 25 letters are assigned to the 25 time zones. The International Date Line separates time zones M and Y. Zulu [Z] is a synonym for Coordinated Universal Time (UTC); and formerly a synonym for Greenwich Mean Time (GMT).", "section_idx": 1, "section_name": "Military Date Time Group", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " MIL-STD-2500A 12 October 1994", "section_idx": 2, "section_name": "Sources", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Calendar date", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 7123 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "ISO 8601", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 15024 ], "anchor_spans": [ [ 0, 8 ] ] }, { "plaintext": "TM 20-205, the Dictionary of United States Army Terms (1944)", "section_idx": 4, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "ACP 121(I) p 3–7", "section_idx": 4, "section_name": "References", "target_page_ids": [], "anchor_spans": [] } ]

[ "Calendars" ]

[]

[ { "plaintext": "DB (until 1947 known as Deutsch-Bonnet) was a French automobile maker between 1938 and 1961, based in Champigny-sur-Marne near Paris. The firm was founded by Charles Deutsch and René Bonnet, an offshoot of the Deutsch family's existing coachbuilding shop which had been taken over by Bonnet in 1932. Immediately before the war the partners concentrated on making light-weight racing cars, but a few years after the war, starting with the presentation of a Panhard based cabriolet at the 1950 Paris Motor Show, the company also began to produce small road-going sports cars. By 1952 the company no longer had its own stand at the Paris Motor Show, but one of their cars appeared as a star attraction on the large Panhard stand, reflecting the level of cooperation between the two businesses.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 13673345, 536812, 162414, 17739181, 32927, 16095379, 1035059, 427068 ], "anchor_spans": [ [ 53, 63 ], [ 102, 121 ], [ 158, 173 ], [ 178, 189 ], [ 323, 326 ], [ 456, 463 ], [ 629, 645 ], [ 712, 719 ] ] }, { "plaintext": "The company was defunct by 1961, as Deutsch and Bonnet's differing design philosophies hamstrung further cooperation. The number of DB's built is not certain; estimates of up to 2,000 cars are mentioned but more conservative numbers are closer to one thousand.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The business produced light sports cars, originally in steel or aluminium but subsequently with fibreglass bodies mainly powered by Panhard flat-twin engines, most commonly of 610, 744, or 848cc. Deutsch was a \"theoretical engineer who had a natural instinct for aerodynamics,\" while Bonnet was a more \"pragmatic mechanical engineer\".", "section_idx": 1, "section_name": "Light-weight engineering", "target_page_ids": [ 146227, 174431, 427068 ], "anchor_spans": [ [ 28, 38 ], [ 96, 106 ], [ 132, 139 ] ] }, { "plaintext": "The fibreglass bodies covered a tubular central beam chassis made from steel, with front wheel drive and four wheel independent suspension directly lifted from the Panhard donors. Until 1952 all DBs had been intended for competition purposes only.", "section_idx": 1, "section_name": "Light-weight engineering", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Bonnet had been promised a works drive in an Amilcar Pégase in the 1936 French Grand Prix for sports cars, but when this failed to materialise they set about building their own racer. The 1938 alloy-bodied DB1 roadster was a special, built using the remains of a Citroën Traction Avant 11CV. The construction took seventeen months. A series of numbered successors followed. The close-roofed 1.5-litre DB2's career was hindered by the war and was sold later, without Deutsch ever using it. The DB3 was a monocoque project developed during the war, but was never built, as the improved pontoon-bodied DB4 took preference. With a central beam chassis with a forked cradle for the 1.5 litre Traction 7A-based engine (originally intended for the DB2) it was finished in July 1945, with most of the work having been carried out in secret during the occupation. The very similar 2-litre DB5 was finished soon thereafter. Their two specials both placed in the first postwar race in France, in Paris in 1945, being the only post-war cars entered. An open-wheeled DB7 appeared in 1947 (preceded by the heavy and large DB6 which saw very little action), after which the Automobiles Deutsch & Bonnet was officially formed.", "section_idx": 2, "section_name": "Racing origins", "target_page_ids": [ 40679265, 43170464, 43170464, 5020586 ], "anchor_spans": [ [ 45, 59 ], [ 263, 285 ], [ 687, 698 ], [ 839, 853 ] ] }, { "plaintext": "Neither single-seater DB was at all successful, but they did show Deutsch - who had hitherto preferred dependable standard units - that a tuned engine would become necessary. DB thus moved into the performance parts market, developing and offering a four-speed conversion for Citroëns and an overhead camshaft head - developed with the aid of engine specialists Maurice Sainturat and Dante Giacosa. The DB8 appeared in 1948, and won two concours d'élegances before partaking in any competitions. Their early cars were all built using Citroën parts, but supply was troublesome and DB soon moved on to using Panhard technology. This relationship came about as Deutsch was an officer of independent racer's club AGACI. When this organization decided to begin a Mouvement Racer 500, modelled on the British Formula 3, Deutsch offered club members the design of a racing car using a Panhard 500 engine. One member asked to have DB build such a car, and after it made a star appearance at the 1949 Paris Salon Panhard was happy to support the construction of about fifteen more. The formula expired in 1951, with the DB Panhard 500 never competitive abroad.", "section_idx": 2, "section_name": "Racing origins", "target_page_ids": [ 879392, 5437742, 3337928, 553257, 1035059 ], "anchor_spans": [ [ 292, 309 ], [ 384, 397 ], [ 437, 457 ], [ 795, 812 ], [ 992, 1003 ] ] }, { "plaintext": "DB was very active in competition, especially in Le Mans 24 Hours and other long distance racing. Nearly all DBs, even the road cars, were designed with competition foremost in mind. In 1952, a DB Speedster was entered in the 12 Hours of Sebring and won its class handsomely, beginning its career in the United States market. Steve Lansing and Ward Morehouse were the drivers.", "section_idx": 2, "section_name": "Racing origins", "target_page_ids": [ 1401596, 685695 ], "anchor_spans": [ [ 49, 65 ], [ 226, 245 ] ] }, { "plaintext": "At the 1954 Le Mans DB entered five cars and were also involved with Panhards \"Monopole\" racers. René Bonnet himself, together with racing legend Élie Bayol, finished tenth overall and best of the DBs. The other Panhard-engined also finished (in 16th), while three Renault-engined central-seater DB designs all failed to complete the race. The Renault-engined designs had been created as a concession to pressure from DB's customers, but they did very badly in the race, in part because of a shortage of preparation time for what was an unknown entity to Deutsch and Bonnet. In either case, DB proceeded to focus on Panhard designs exclusively.", "section_idx": 2, "section_name": "Racing origins", "target_page_ids": [ 5111259, 63079876, 1228323 ], "anchor_spans": [ [ 7, 19 ], [ 79, 87 ], [ 146, 156 ] ] }, { "plaintext": "The 1949 DB8 was bodied by Antem of Belgium and shown at the 1949 Paris Salon. While a handsome (winning two concours d'élegances) and modern design, Citroën refused to allow the provision of parts for series production. After DB began to depend on Panhard for engines, Antem was again commissioned to make a cabriolet with the intent to build a small series of street cars. long, the car weighed and used the Dyna's 750cc flat-two and much of the suspension and drivetrain. As with most DBs, it had a central frame with two outliers. An 850cc version was also offered, a model which could reach 140 rather than the 125–130km/h of the smaller one. Naturally, Panhard developed a racing barquette version (called the Tank) of the Antem cabriolet. These competed at Le Mans 1951 as well as several other races. About twenty Antem cabriolets were built in 1951, but DB chose to let it die in favor of a coupé version of the same (\"Coach\" in French). A few DB-Antem Coach were built, mostly for competition. These had bodywork designed by Deutsch, and again mainly relied on Dyna underpinnings and a central steel-tube frame.", "section_idx": 3, "section_name": "Road cars", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The steel-bodied, Frua-designed 1952 \"Mille Miles\" (celebrating class victories at the Mille Miglia) was a mini-GT with a 65hp Panhard two-cylinder. It was somewhat expensive, and at the 1953 Paris Salon a Chausson-designed DB Coach in fibreglass, although it did not enter production until 1954. The HBR 4/5 model (1954–1959) was the partners' most successful project to date, with several hundred of the little cars produced between 1954 and 1959. This was followed by the Le Mans convertible and hardtop, which was shown in 1959 and built by DB until 1962, and continued until 1964 by René Bonnet. About 660 of the Mille Miles/Coach/HBR were built, and 232 DB Le Mans (not including the Bonnet-built cars). Later versions could be equipped with engines of 1 and 1.3litres, and superchargers were also available. No two cars may have been alike, as they were built according to customer specifications from a wide range of options.", "section_idx": 3, "section_name": "Road cars", "target_page_ids": [ 491326, 617045, 1035059, 36225436, 37016861, 492599 ], "anchor_spans": [ [ 18, 22 ], [ 87, 99 ], [ 192, 203 ], [ 301, 308 ], [ 476, 483 ], [ 589, 600 ] ] }, { "plaintext": "Deutsch's very efficient and influential aerodynamic designs allowed DB race cars to reach impressive top speeds despite the small Panhard flat-twin engine. DB's received class victories at Le Mans (three times), Sebring (twice), and Mille Miglia (four times). DB even managed an outright win in the handicapped 1954 Tourist Trophy sports car race, with Laureau and Armagnac driving. DB always showed strongly in the \"Index of Performance\", a category especially suitable for DB's small-engined, aerodynamic little racers. The Index of Performance is perhaps best known at the Le Mans 24 hours competition, but the category also existed at many French automobile races of the era, such as the Tour de France. DBs were also successful in American SCCA racing, where they racked up an impressive number of victories in the H-sports category.", "section_idx": 4, "section_name": "More racing success", "target_page_ids": [ 199969, 685695, 1495803, 14635980, 28242 ], "anchor_spans": [ [ 139, 148 ], [ 213, 220 ], [ 300, 311 ], [ 317, 331 ], [ 746, 750 ] ] }, { "plaintext": "Deutsch and Bonnet disagreed whether they should build cars of front-wheel drive or mid-engined design. There was also disagreement on which engines to use. Charles Deutsch, wanting to stick to Panhard engines, left DB in 1961 to found his own firm (CD). Bonnet founded Automobiles René Bonnet, producing mid-engined cars equipped with Renault power units: this business was later to become part of Matra Automobiles. Deutsch ended up an engineering consultant.", "section_idx": 5, "section_name": "Disagreement and the end of the partnership", "target_page_ids": [ 54100447, 492599, 162292, 80980 ], "anchor_spans": [ [ 250, 252 ], [ 270, 293 ], [ 336, 343 ], [ 399, 404 ] ] }, { "plaintext": "Deutsch Bonnet at Citroenet", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Defunct_motor_vehicle_manufacturers_of_France", "Sports_car_manufacturers", "French_racecar_constructors", "24_Hours_of_Le_Mans_teams" ]

[]

[ { "plaintext": "A weighting filter is used to emphasize or suppress some aspects of a phenomenon compared to others, for measurement or other purposes.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In each field of audio measurement, special units are used to indicate a weighted measurement as opposed to a basic physical measurement of energy level. For sound, the unit is the phon (1kHz equivalent level).", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 215441, 14121 ], "anchor_spans": [ [ 181, 185 ], [ 188, 191 ] ] }, { "plaintext": "Sound has three basic components, the wavelength, frequency, and speed. In sound measurement, we measure the loudness of the sound in decibels (dB). Decibels are logarithmic with 0dB as the reference. There are also a range of frequencies that sounds can have. Frequency is the number of times a sine wave repeats itself in a second. Normal auditory systems can usually hear between 20 and 20,000Hz. When we measure sound, the measurement instrument takes the incoming auditory signal and analyzes it for these different features. Weighting filters in these instruments then filter out certain frequencies and decibel levels depending on the filter. A weighted filters are most similar to natural human hearing. This allows the sound level meter to determine what decibel level the incoming sound would likely be for a normal hearing human's auditory system.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 33125, 10779, 147853, 8410, 164055, 426407, 635490 ], "anchor_spans": [ [ 38, 48 ], [ 50, 59 ], [ 65, 70 ], [ 134, 141 ], [ 162, 173 ], [ 180, 182 ], [ 341, 356 ] ] }, { "plaintext": "In the measurement of loudness, for example, an A-weighting filter is commonly used to emphasize frequencies around 3–6kHz where the human ear is most sensitive, while attenuating very high and very low frequencies to which the ear is insensitive. The aim is to ensure that measured loudness corresponds well with subjectively perceived loudness.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 11217018, 40735 ], "anchor_spans": [ [ 48, 59 ], [ 168, 179 ] ] }, { "plaintext": "A-weighting is only really valid for relatively quiet sounds and for pure tones as it is based on the 40-phon Fletcher–Munson equal-loudness contour. The B and C curves were intended for louder sounds (though they are less used) while the D curve is used in assessing loud aircraft noise (IEC 537). B curves filter out more medium loudness levels when compared to an A curves. This curve is rarely ever used in the assessment or monitoring of noise levels anymore. C curves differ from both A and B in the fact that they filter less of the lower and higher frequencies. The filter is a much flatter shape and is used in sound measurement in especially loud and noisy environments. A weighted curves follow a 40 phon curve while C weighted follows a 100 phon curve. The three curves differ not in their measurement of exposure levels, but in the frequencies measured. A weighted curves allow more frequencies equal to or less than 500Hz through, which is most representative of the human ear.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 1046687, 1046687, 11217018, 11217018, 11217018 ], "anchor_spans": [ [ 110, 125 ], [ 126, 148 ], [ 154, 155 ], [ 160, 167 ], [ 239, 246 ] ] }, { "plaintext": "There are a variety of reasons for measuring sound. This includes following regulations to protect worker's hearing, following noise ordinances, in telecommunications, and many more. At the basis of sound measurement is the idea of breaking down an incoming signal based on its different properties. Every incoming sinusoidal wave of sound has a frequency and amplitude. Using this information, a sound level can be deduced from the root-sums-of-squares of the amplitudes of all the incoming auditory information. Whether using a sound level meter or a noise dosimeter, the processing is somewhat similar. With a calibrated sound level meter, the incoming sounds are going to be picked up by the microphone and then measured by the internal electronic circuits. The sound measurement that the device outputs can be filtered through an A, B, or C weighting curve. The curve used will have slight effects on the resulting decibel level.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 9491192, 4324783, 33094374, 3969529, 13093027 ], "anchor_spans": [ [ 91, 115 ], [ 127, 142 ], [ 148, 165 ], [ 532, 549 ], [ 555, 570 ] ] }, { "plaintext": "In the field of telecommunications, weighting filters are widely used in the measurement of electrical noise on telephone circuits, and in the assessment of noise as perceived through the acoustic response of different types of instrument (handset). Other noise-weighting curves have existed, e.g. DIN standards. The term psophometric weighting, though referring in principle to any weighting curve intended for noise measurement, is often used to refer to a particular weighting curve, used in telephony for narrow-bandwidth voiceband speech circuits.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 33094374, 8062, 3973839, 41855 ], "anchor_spans": [ [ 16, 33 ], [ 298, 301 ], [ 322, 344 ], [ 526, 535 ] ] }, { "plaintext": "A-weighted decibels are abbreviated dB(A) or dBA. When acoustic (calibrated microphone) measurements are being referred to, then the units used will be dB SPL (sound pressure level) referenced to 20 micropascals = 0dB SPL.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 11217018, 8410, 47502, 8410, 495884, 495884 ], "anchor_spans": [ [ 0, 10 ], [ 11, 18 ], [ 65, 75 ], [ 152, 154 ], [ 155, 158 ], [ 160, 180 ] ] }, { "plaintext": "The A-weighting curve has been widely adopted for environmental noise measurement, and is standard in many sound level meters (see ITU-R 468 weighting for a further explanation).", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 2980850 ], "anchor_spans": [ [ 131, 140 ] ] }, { "plaintext": "A-weighting is also in common use for assessing potential hearing damage caused by loud noise, though this seems to be based on the widespread availability of sound level meters incorporating A-Weighting rather than on any good experimental evidence to suggest that such use is valid. The distance of the measuring microphone from a sound source is often \"forgotten\", when SPL measurements are quoted, making the data useless. In the case of environmental or aircraft noise, distance need not be quoted as it is the level at the point of measurement that is needed, but when measuring refrigerators and similar appliances the distance should be stated; where not stated it is usually one metre (1 m). An extra complication here is the effect of a reverberant room, and so noise measurement on appliances should state \"at 1 m in an open field\" or \"at 1 m in anechoic chamber\". Measurements made outdoors will approximate well to anechoic conditions.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 49604, 247935, 1036259, 300082 ], "anchor_spans": [ [ 58, 72 ], [ 459, 473 ], [ 585, 597 ], [ 858, 874 ] ] }, { "plaintext": "A-weighted SPL measurements of noise level are increasingly to be found on sales literature for domestic appliances such as refrigerators and freezers, and computer fans. Although the threshold of hearing is typically around 0dB SPL, this is in fact very quiet indeed, and appliances are more likely to have noise levels of 30 to 40dB SPL.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Human sensitivity to noise in the region of 6kHz became particularly apparent in the late 1960s with the introduction of compact cassette recorders and Dolby-B noise reduction. A-weighted noise measurements were found to give misleading results because they did not give sufficient prominence to the 6kHz region where the noise reduction was having greatest effect, and sometimes one piece of equipment would even measure worse than another and yet sound better, because of differing spectral content.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 65880, 87710 ], "anchor_spans": [ [ 121, 137 ], [ 152, 175 ] ] }, { "plaintext": "ITU-R 468 noise weighting was therefore developed to more accurately reflect the subjective loudness of all types of noise, as opposed to tones. This curve, which came out of work done by the BBC Research Department, and was standardised by the CCIR and later adopted by many other standards bodies (IEC, BSI/) and, , is maintained by the ITU. Noise measurements using this weighting typically also use a quasi-peak detector law rather than slow averaging. This also helps to quantify the audibility of bursty noise, ticks and pops that might go undetected with a slow rms measurement.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 2980850, 19344654, 15210, 15144, 9385162 ], "anchor_spans": [ [ 0, 25 ], [ 192, 195 ], [ 245, 249 ], [ 300, 303 ], [ 305, 308 ] ] }, { "plaintext": "ITU-R 468 noise weighting with quasi-peak detection is widely used in Europe, especially in telecommunications, and in broadcasting particularly after it was adopted by the Dolby corporation who realised its superior validity for their purposes. Its advantages over A-weighting seem to be less well appreciated in the USA and in consumer electronics, where the use of A-weighting predominates—probably because A-weighting produces a 9 to 12dB \"better\" specification, see specsmanship. It is commonly used by broadcasters in Britain, Europe, and former countries of the British Empire such as Australia and South Africa.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 6629503 ], "anchor_spans": [ [ 471, 483 ] ] }, { "plaintext": "Though the noise level of 16-bit audio systems (such as CD players) is commonly quoted (on the basis of calculations that take no account of subjective effect) as −96dB relative to FS (full scale), the best 468-weighted results are in the region of −68dB relative to Alignment Level (commonly defined as 18dB below FS) i.e. −86dB relative to FS.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The use of weighting curves is in no way to be regarded as 'cheating', provided that the proper curve is used. Nothing of relevance is being 'hidden', and even when, for example, hum is present at 50 or 100Hz at a level above the quoted (weighted) noise floor this is of no importance because our ears are very insensitive to low frequencies at low levels, so it will not be heard. A-weighting is often used to compare and qualify ADCs, for instance, because it more accurately represents the way noise shaping hides dither noise in the ultrasonic range.", "section_idx": 1, "section_name": "Audio applications", "target_page_ids": [ 40367, 1244240, 1243526, 31780 ], "anchor_spans": [ [ 432, 435 ], [ 498, 511 ], [ 518, 524 ], [ 538, 548 ] ] }, { "plaintext": "In the measurement of gamma rays or other ionising radiation, a radiation monitor or dosimeter will commonly use a filter to attenuate those energy levels or wavelengths that cause the least damage to the human body, while letting through those that do the most damage, so that any source of radiation may be measured in terms of its true danger rather than just its 'strength'. The sievert is a unit of weighted radiation dose for ionising radiation, which supersedes the older unit the REM (roentgen equivalent man).", "section_idx": 2, "section_name": "Other applications of weighting", "target_page_ids": [ 18616290, 202522, 40363, 155823, 202522, 559764, 23783987 ], "anchor_spans": [ [ 22, 32 ], [ 42, 60 ], [ 85, 94 ], [ 383, 390 ], [ 432, 450 ], [ 488, 491 ], [ 493, 501 ] ] }, { "plaintext": "Weighting is also applied to the measurement of sunlight when assessing the risk of skin damage through sunburn, since different wavelengths have different biological effects. Common examples are the SPF of sunscreen, and the UV index.", "section_idx": 2, "section_name": "Other applications of weighting", "target_page_ids": [ 20647810, 294419, 1871740 ], "anchor_spans": [ [ 104, 111 ], [ 200, 203 ], [ 226, 234 ] ] }, { "plaintext": "Another use of weighting is in television, where the red, green and blue components of the signal are weighted according to their perceived brightness. This ensures compatibility with black and white receivers, and also benefits noise performance and allows separation into meaningful luminance and chrominance signals for transmission.", "section_idx": 2, "section_name": "Other applications of weighting", "target_page_ids": [ 6928954, 6945 ], "anchor_spans": [ [ 285, 294 ], [ 299, 310 ] ] }, { "plaintext": " Weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 3003284 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Weighting curve", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 1586499 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Sone", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 215436 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": " Phon", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 215441 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": " ITU-R 468 noise weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2980850 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Psophometric weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 3973839 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Equal-loudness contour", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 1046687 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Noise pollution", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 66599 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Noise regulation", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 4324783 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " A-weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 11217018 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " B-weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 11217018 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " C-weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 11217018 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " D-weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 11217018 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " G-weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 11217018 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " M-weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2980850 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Z-weighting", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 11217018 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Noise measurement briefing", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Calculator for A,C,U, and AU weighting values ", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A-weighting filter circuit for audio measurements", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " AES pro audio reference definition of \"weighting filters\"", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " What is a decibel?", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Weighting filter according DIN EN 61672-1 2003-10 (DIN-IEC 651) Calculation: frequency f to dBA and dBC", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Audio_engineering", "Acoustics", "Sound", "Radiation", "Light" ]

[]

[ { "plaintext": "dBm or dBmW (decibel-milliwatts) is a unit of level used to indicate that a power level is expressed in decibels (dB) with reference to one milliwatt (mW). It is used in radio, microwave and fiber-optical communication networks as a convenient measure of absolute power because of its capability to express both very large and very small values in a short form. dBW is a similar unit, referenced to one watt (1000mW).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 39999171, 8410, 21347693, 24236, 660026 ], "anchor_spans": [ [ 46, 51 ], [ 104, 111 ], [ 140, 149 ], [ 264, 269 ], [ 362, 365 ] ] }, { "plaintext": "The decibel (dB) is a dimensionless unit, used for quantifying the ratio between two values, such as signal-to-noise ratio. The dBm is also dimensionless, but since it compares to a fixed reference value, the dBm rating is an absolute one.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 51331, 41706 ], "anchor_spans": [ [ 22, 40 ], [ 101, 122 ] ] }, { "plaintext": "The dBm is not a part of the International System of Units (SI) and therefore is discouraged from use in documents or systems that adhere to SI units (the corresponding SI unit is the watt). However, the unit decibel (dB), without the 'm' suffix, is permitted for relative quantities, but not accepted for use directly alongside SI units. 10 dBm may be written 10 dB (1 mW) in SI.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26764, 8410 ], "anchor_spans": [ [ 29, 58 ], [ 209, 216 ] ] }, { "plaintext": "In audio and telephony, dBm is typically referenced relative to a 600-ohm impedance, while in radio-frequency work dBm is typically referenced relative to a 50-ohm impedance.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41957 ], "anchor_spans": [ [ 74, 83 ] ] }, { "plaintext": "A power level of 0dBm corresponds to a power of 1 milliwatt. A 10dB increase in level is equivalent to a 10-fold increase in power. Therefore, a 20dB increase in level is equivalent to a 100-fold increase in power. A 3dB increase in level is approximately equivalent to doubling the power, which means that a level of 3dBm corresponds roughly to a power of 2mW. Similarly, for each 3dB decrease in level, the power is reduced by about one half, making −3dBm correspond to a power of about 0.5mW.", "section_idx": 1, "section_name": "Unit conversions", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "To express an arbitrary power P in mW as x in dBm, the following expression may be used:", "section_idx": 1, "section_name": "Unit conversions", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Conversely, to express an arbitrary power level x in dBm, as P in mW:", "section_idx": 1, "section_name": "Unit conversions", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Below is a table summarizing useful cases:", "section_idx": 2, "section_name": "Table of Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The signal intensity (power per unit area) can be converted to received signal power by multiplying by the square of the wavelength and dividing by 4π (see Free-space path loss).", "section_idx": 3, "section_name": "Standards", "target_page_ids": [ 41179 ], "anchor_spans": [ [ 156, 176 ] ] }, { "plaintext": "In United States Department of Defense practice, unweighted measurement is normally understood, applicable to a certain bandwidth, which must be stated or implied.", "section_idx": 3, "section_name": "Standards", "target_page_ids": [ 7279897, 41002, 3967 ], "anchor_spans": [ [ 3, 38 ], [ 49, 59 ], [ 120, 129 ] ] }, { "plaintext": "In European practice, psophometric weighting may be, as indicated by context, equivalent to dBm0p, which is preferred.", "section_idx": 3, "section_name": "Standards", "target_page_ids": [ 3973839 ], "anchor_spans": [ [ 22, 44 ] ] }, { "plaintext": "In audio, 0 dBm often corresponds to approximately 0.775 volts, since 0.775V dissipates 1mW in a 600Ω load. The corresponding voltage level is 0 dBu, without the 600 Ω restriction. Conversely, for RF situations with a 50Ω load, 0dBm corresponds to approximately 0.224 volts, since 0.224V dissipates 1mW in a 50Ω load.", "section_idx": 3, "section_name": "Standards", "target_page_ids": [ 8410 ], "anchor_spans": [ [ 145, 148 ] ] }, { "plaintext": "In general the relationship between the power level P in dBms and the RMS voltage V in volts across a load of resistance R (typically used to terminate a transmission line with impedance Z) is:", "section_idx": 3, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Expression in dBm is typically used for optical and electrical power measurements, not for other types of power (such as thermal). A listing by power levels in watts is available that includes a variety of examples not necessarily related to electrical or optical power.", "section_idx": 3, "section_name": "Standards", "target_page_ids": [ 229745 ], "anchor_spans": [ [ 133, 165 ] ] }, { "plaintext": "The dBm was first proposed as an industry standard in the paper \"A New Standard Volume Indicator and Reference Level\".", "section_idx": 3, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " dBW", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 660026 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " Decibel", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 8410 ], "anchor_spans": [ [ 1, 8 ] ] }, { "plaintext": " The dBm calculator for impedance matching", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Convert dBm to watts", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Units_of_power", "Radio_frequency_propagation", "Logarithmic_scales_of_measurement" ]

[ "dBm", "decibel milliwatts" ]

[ { "plaintext": "The symbol dBrn or dB(rn) is an abbreviation for decibels above reference noise. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8410, 41639 ], "anchor_spans": [ [ 49, 57 ], [ 64, 79 ] ] }, { "plaintext": "Weighted noise power in dB is referred to 1.0 picowatt. Thus, 0 dBrn = -90 dBm. Use of 144 line, 144-receiver, or C-message weighting, or flat weighting, can be indicated in parentheses.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41419, 21347693, 41003, 9559, 3973839, 41158, 59338 ], "anchor_spans": [ [ 9, 20 ], [ 46, 54 ], [ 75, 78 ], [ 91, 95 ], [ 114, 133 ], [ 138, 152 ], [ 174, 185 ] ] }, { "plaintext": "With C-message weighting, a one-milliwatt, 1000 Hz tone will read +90 dBrn, but the same power as white noise, randomly distributed over a 3 kHz band will read approximately +88.5 dBrn, because of the frequency weighting. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 21347693, 14121, 46182, 634183, 10779 ], "anchor_spans": [ [ 32, 41 ], [ 48, 50 ], [ 98, 109 ], [ 145, 149 ], [ 201, 210 ] ] }, { "plaintext": "With 144 weightings, a one milliwatt, 1000 Hz white noise tone will also read +90 dBrn, but the same 3 kHz power will only read +82 dBrn, because of the different frequency weighting.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41002 ], "anchor_spans": [ [ 163, 182 ] ] }, { "plaintext": "Note: In telecommunications, dBrn adjusted also called dBa denotes \"decibels adjusted\", i.e. weighted absolute noise power. This is totally unrelated to and not a synonym for dB(A).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 11217018 ], "anchor_spans": [ [ 175, 180 ] ] } ]

[ "Mechanics", "Units_of_measurement", "Logarithmic_scales_of_measurement" ]

[ "decibels above reference noise" ]

[ { "plaintext": "A data circuit-terminating equipment (DCE) is a device that sits between the data terminal equipment (DTE) and a data transmission circuit. It is also called data communication(s) equipment and data carrier equipment. Usually, the DTE device is the terminal (or computer), and the DCE is a modem.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 74041, 40999, 460792, 7878457, 20647197 ], "anchor_spans": [ [ 77, 100 ], [ 113, 138 ], [ 249, 257 ], [ 262, 270 ], [ 290, 295 ] ] }, { "plaintext": "In a data station, the DCE performs functions such as signal conversion, coding, and line clocking and may be a part of the DTE or intermediate equipment. Interfacing equipment may be required to couple the DTE into a transmission circuit or channel and from a transmission circuit or channel into the DTE.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18985040, 41703, 4237207, 156700 ], "anchor_spans": [ [ 5, 9 ], [ 54, 60 ], [ 73, 79 ], [ 242, 249 ] ] }, { "plaintext": "Although the terms are most commonly used with RS-232, several data communication standards define different types of interfaces between a DCE and a DTE. The DCE is a device that communicates with a DTE device in these standards. Standards that use this nomenclature include:", "section_idx": 1, "section_name": "Usage", "target_page_ids": [ 26023 ], "anchor_spans": [ [ 47, 53 ] ] }, { "plaintext": " Federal Standard 1037C, MIL-STD-188", "section_idx": 1, "section_name": "Usage", "target_page_ids": [ 37310, 41882 ], "anchor_spans": [ [ 1, 23 ], [ 25, 36 ] ] }, { "plaintext": " RS-232", "section_idx": 1, "section_name": "Usage", "target_page_ids": [ 26023 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " Certain ITU-T standards in the V series (notably V.24 and V.35)", "section_idx": 1, "section_name": "Usage", "target_page_ids": [ 14744, 26023, 5419226 ], "anchor_spans": [ [ 9, 14 ], [ 50, 54 ], [ 59, 63 ] ] }, { "plaintext": " Certain ITU-T standards in the X series (notably X.21 and X.25)", "section_idx": 1, "section_name": "Usage", "target_page_ids": [ 14744, 649708, 43336 ], "anchor_spans": [ [ 9, 14 ], [ 50, 54 ], [ 59, 63 ] ] }, { "plaintext": "A general rule is that DCE devices provide the clock signal (internal clocking) and the DTE device synchronizes on the provided clock (external clocking). D-sub connectors follow another rule for pin assignment. DTE devices usually transmit on pin connector number 2 and receive on pin connector number 3. DCE devices are just the opposite: pin connector number 2 receives and pin connector number 3 transmits the signals.", "section_idx": 1, "section_name": "Usage", "target_page_ids": [ 383705 ], "anchor_spans": [ [ 155, 160 ] ] }, { "plaintext": "When two devices, that are both DTE or both DCE, must be connected together without a modem or a similar media translator between them, a crossover cable must be used, e.g. a null modem for RS-232 or an Ethernet crossover cable/body", "section_idx": 1, "section_name": "Usage", "target_page_ids": [ 972519, 627136, 9499 ], "anchor_spans": [ [ 138, 153 ], [ 175, 185 ], [ 203, 211 ] ] }, { "plaintext": "Networking hardware", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 1699254 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": " Data Terminating Equipment or Data Circuit-Terminating Equipment speeds, IBM", "section_idx": 4, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Data_transmission", "Telecommunications_equipment" ]

[ "Data circuit-terminating equipment, DCE" ]

[ { "plaintext": "Degradation may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Degradation (geology), lowering of a fluvial surface by erosion", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 24169775 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Degradation (telecommunications), of an electronic signal", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 7876158 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Biodegradation of organic substances by living organisms", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 47490 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Environmental degradation in ecology", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 846000 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Land degradation, a process in which the value of the biophysical environment is affected by a combination of human-induced processes acting upon the land", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 1436198 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Polymer degradation, as plastics age", "section_idx": 1, "section_name": "Science", "target_page_ids": [ 530817 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Elegant degradation, gradual rather than sudden", "section_idx": 2, "section_name": "Other", "target_page_ids": [ 2608153 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Graceful degradation, in a fault-tolerant system", "section_idx": 2, "section_name": "Other", "target_page_ids": [ 2091393 ], "anchor_spans": [ [ 29, 50 ] ] }, { "plaintext": " Degradation (knighthood), revocation of knighthood", "section_idx": 2, "section_name": "Other", "target_page_ids": [ 26236745 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Cashiering, whereby a military officer is dismissed for misconduct", "section_idx": 2, "section_name": "Other", "target_page_ids": [ 5951960 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Reduction in rank, whereby a military officer is reduced to a lower rank for misconduct", "section_idx": 2, "section_name": "Other", "target_page_ids": [ 12303440 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Degradation, the former ceremony of defrocking a disgraced priest", "section_idx": 2, "section_name": "Other", "target_page_ids": [ 303299 ], "anchor_spans": [ [ 37, 47 ] ] }, { "plaintext": " Degradation, a song by the Violent Femmes, from Add It Up (1981–1993)", "section_idx": 2, "section_name": "Other", "target_page_ids": [ 1858606 ], "anchor_spans": [ [ 49, 70 ] ] }, { "plaintext": " Dégradé, 2015 Palestinian film", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 46462286 ], "anchor_spans": [ [ 1, 8 ] ] } ]

[]

[]

[ { "plaintext": "The degree of isochronous distortion, in data transmission, is the ratio of the absolute value of the maximum measured difference between the actual and the theoretical intervals separating any two significant instants of modulation (or demodulation), to the unit interval. These instants are not necessarily consecutive. This value is usually expressed as a percentage.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42168, 20637, 66926, 49324 ], "anchor_spans": [ [ 41, 58 ], [ 222, 232 ], [ 237, 249 ], [ 259, 272 ] ] }, { "plaintext": "The result of the measurement should be qualified by an indication if the period, usually limited, of the observation. For a prolonged modulation (or demodulation), it will be appropriate to consider the probability that an assigned value of the degree of distortion will be exceeded.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Data_transmission" ]

[]

[ { "plaintext": "In telecommunication, the term degree of start-stop distortion has the following meanings: ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " In asynchronous serial communication data transmission, the ratio of (a) the absolute value of the maximum measured difference between the actual and theoretical intervals separating any significant instant of modulation (or demodulation) from the significant instant of the start element immediately preceding it to (b) the unit interval. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 200992, 42168, 991, 20637, 66926, 2078753 ], "anchor_spans": [ [ 4, 37 ], [ 38, 55 ], [ 78, 92 ], [ 211, 221 ], [ 226, 238 ], [ 326, 339 ] ] }, { "plaintext": " The highest absolute value of individual distortion affecting the significant instants of a start-stop modulation. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41052 ], "anchor_spans": [ [ 42, 52 ] ] }, { "plaintext": "The degree of distortion of a start-stop modulation (or demodulation) is usually expressed as a percentage. Distinction can be made between the degree of late (positive) distortion and the degree of early (negative) distortion.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telecommunications_engineering", "Data_transmission" ]

[]

[ { "plaintext": "Delay (from Latin: dilatio) may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Delay 1968, a 1981 album by German experimental rock band Can", "section_idx": 1, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 4144801 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " The Delay, a 2012 Uruguayan film", "section_idx": 1, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 37174783 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " B. H. DeLay (1891–1923), American aviator and actor", "section_idx": 2, "section_name": "People", "target_page_ids": [ 1453845 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Dorothy DeLay (1917–2002), American violin instructor", "section_idx": 2, "section_name": "People", "target_page_ids": [ 1994357 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Florence Delay (born 1941), French academician and actor", "section_idx": 2, "section_name": "People", "target_page_ids": [ 3319285 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Jan Delay (born 1976), German musician", "section_idx": 2, "section_name": "People", "target_page_ids": [ 3610992 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Jean Delay (1907–1987), French psychiatrist, neurologist, and writer", "section_idx": 2, "section_name": "People", "target_page_ids": [ 22813343 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Paul deLay (1952–2007), American blues musician", "section_idx": 2, "section_name": "People", "target_page_ids": [ 9938546 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Tom DeLay (born 1947), American politician", "section_idx": 2, "section_name": "People", "target_page_ids": [ 216169 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Vladislav Delay (born 1976), Finnish musician", "section_idx": 2, "section_name": "People", "target_page_ids": [ 253214 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Delay (audio effect), a technology for producing delayed playback of an audio signal", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 5215871 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Delay (programming), a programming language construct for delaying evaluation of an expression", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 2203507 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Analog delay line, used to delay a signal", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 6993227 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Broadcast delay, a practice of time-shifting transmissions", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 1136392 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Delay differential equation, which describes or governs the dynamics of a time-delay system in terms of its values at previous times", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 3941333 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Delay encoding, a radio transmission technique", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 383902 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Delay line (disambiguation)", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 41014 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Delay-line memory, a type of random-access memory", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 197673 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Delay-line oscillator, a form of electronic oscillator that uses a delay line as its principal timing element", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 17507715 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Delay slot, a computer instruction slot that gets executed without the effects of a preceding instruction", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 352818 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Delay-gradient congestion control, a class of network congestion control algorithms, which react to the differences in round-trip delay time (RTT)", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 48463935 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Delay-locked loop (DLL), is a digital electronic circuit similar to a phase-locked loop (PLL)", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 3012612 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Digital delay generator, or digital-to-time converter, a piece of electronic test equipment that provides precise delays for triggering, syncing, delaying and gating events", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 5954836 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " End-to-end delay, or one-way delay (OWD), the time taken for a packet to be transmitted across a network from source to destination", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 1123698 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Group delay and phase delay, time delay of the amplitude envelopes of the various sinusoidal components of a signal", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 41222 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Network delay, the delay of an IP packet within an IP network", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 10145584 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Propagation delay, a measurement of the time for a signal to reach its destination", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 1275395 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Queuing delay, or queueing delay, the time a job waits in a queue until it can be executed", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 41616 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Satellite delay, the noticeable latency, which occurs due to the speed of light, when sending data to and from satellites", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 43364546 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Transmission delay, store-and-forward delay or packetization delay, the network delay caused by the data-rate of the link", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 13576258 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Bi-directional delay line, a numerical analysis technique used in computer simulation for solving ordinary differential equations by converting them to hyperbolic equations", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 1729755 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Delay composition, delay charge or delay train, a pyrotechnic chemical mixture used to delay the firing of an explosion (delay-action bomb)", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 21051994 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Delayed gratification, the ability to resist the temptation for an immediate reward and wait for a later reward", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 2733733 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Shapiro time delay, a test used to confirm general relativity", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 1078521 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Speech delay, also known as alalia, refers to a delay in the development or use of the mechanisms that produce speech", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 2302106 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Delay of game, an action in a sports game in which a player or team deliberately stalls the game", "section_idx": 4, "section_name": "Sports", "target_page_ids": [ 10073716 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": "Delaying payment of a debt, a crime in the United Kingdom, under the Theft Act 1978", "section_idx": 5, "section_name": "Other uses", "target_page_ids": [ 2750076 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": " Delay line (disambiguation)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 41014 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Delaye", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 70510616 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " Echo", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 238901 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": " Laches (equity), unreasonable delay in pursuing a legal action", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 18465 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Lag (disambiguation)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 4090361 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Latency (disambiguation)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 1842184 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Procrastination", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 149973 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Response time (disambiguation)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 8059032 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Sound", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 18994087 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " Speed", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 28748 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " Time", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 30012 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": " Time dilation, relativistic effect between two events occurring in different reference frames or gravitational fields", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 297839 ], "anchor_spans": [ [ 1, 14 ] ] } ]

[]

[]

[ { "plaintext": "Delay line may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Propagation delay, the length of time taken for something to reach its destination", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1275395 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Analog delay line, used to delay a signal", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 6993227 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Bi-directional delay line, a numerical analysis technique used in computer simulation for solving ordinary differential equations by converting them to hyperbolic equations", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1729755 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Digital delay line, a sequential logic element", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 12883102 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Delay-line memory, a form of computer memory used on some of the earliest digital computers", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 197673 ], "anchor_spans": [ [ 1, 18 ] ] } ]

[]

[]

[ { "plaintext": "A delta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance. DM is the simplest form of differential pulse-code modulation (DPCM) where the difference between successive samples is encoded into n-bit data streams. In delta modulation, the transmitted data are reduced to a 1-bit data stream. Its main features are:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40367, 92943, 1093399 ], "anchor_spans": [ [ 46, 63 ], [ 68, 92 ], [ 228, 262 ] ] }, { "plaintext": " The analog signal is approximated with a series of segments.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Each segment of the approximated signal is compared to the preceding bits and the successive bits are determined by this comparison.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Only the change of information is sent, that is, only an increase or decrease of the signal amplitude from the previous sample is sent whereas a no-change condition causes the modulated signal to remain at the same 0 or 1 state of the previous sample.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18985062 ], "anchor_spans": [ [ 20, 31 ] ] }, { "plaintext": "To achieve high signal-to-noise ratio, delta modulation must use oversampling techniques, that is, the analog signal is sampled at a rate several times higher than the Nyquist rate.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41706, 1339640, 41435 ], "anchor_spans": [ [ 16, 37 ], [ 65, 77 ], [ 168, 180 ] ] }, { "plaintext": "Derived forms of delta modulation are continuously variable slope delta modulation, delta-sigma modulation, and differential modulation. Differential pulse-code modulation is the superset of DM.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 20637, 640949, 1745452, 1093399 ], "anchor_spans": [ [ 23, 33 ], [ 38, 82 ], [ 84, 106 ], [ 137, 171 ] ] }, { "plaintext": "Rather than quantizing the value of the input analog waveform, delta modulation quantizes the difference between the current and the previous step, as shown in the block diagram in Fig.1.", "section_idx": 1, "section_name": "Principle", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The modulator is made by a quantizer which converts the difference between the input signal and the integral of the previous steps. In its simplest form, the quantizer can be realized with a comparator referenced to 0 (two levels quantizer), whose output is 1 or 0 if the input signal is positive or negative. The demodulator is simply an integrator (like the one in the feedback loop) whose output rises or falls with each 1 or 0 received. The integrator itself constitutes a low-pass filter.", "section_idx": 1, "section_name": "Principle", "target_page_ids": [ 56484 ], "anchor_spans": [ [ 478, 493 ] ] }, { "plaintext": "The two sources of noise in delta modulation are \"slope overload\", when step size is too small to track the original waveform, and \"granularity\", when step size is too large.", "section_idx": 2, "section_name": "Transfer characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "But a 1971 study shows that slope overload is less objectionable compared to granularity than one might expect based solely on SNR measures.", "section_idx": 2, "section_name": "Transfer characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In delta modulation there is a restriction on the amplitude of the input signal, because if the transmitted signal has a large derivative (abrupt changes) then the modulated signal can not follow the input signal and slope overload occurs. E.g. if the input signal is", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": ",", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "the modulated signal (derivative of the input signal) which is transmitted by the modulator is", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": ",", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "whereas the condition to avoid slope overload is", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": ".", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "So the maximum amplitude of the input signal can be", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": ",", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where fs is the sampling frequency and ω is the frequency of the input signal and σ is step size in quantization. So Amax is the maximum amplitude that DM can transmit without causing the slope overload and the power of transmitted signal depends on the maximum amplitude.", "section_idx": 3, "section_name": "Output signal power", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "If the communication channel is of limited bandwidth, there is the possibility of interference in either DM or PCM. Hence, 'DM' and 'PCM' operate at same bit-rate which is equal to N times the sampling frequency.", "section_idx": 4, "section_name": "Bit-rate", "target_page_ids": [ 25513330 ], "anchor_spans": [ [ 111, 114 ] ] }, { "plaintext": "Adaptive delta modulation (ADM) was first published by Dr. John E. Abate (AT&T Bell Laboratories Fellow) in his doctoral thesis at NJ Institute Of Technology in 1968. ADM was later selected as the standard for all NASA communications between mission control and space-craft.", "section_idx": 5, "section_name": "Adaptive delta modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the mid-1980s, Massachusetts audio company DBX marketed a commercially unsuccessful digital recording system based on adaptive delta modulation. See DBX 700.", "section_idx": 5, "section_name": "Adaptive delta modulation", "target_page_ids": [ 4786858 ], "anchor_spans": [ [ 152, 159 ] ] }, { "plaintext": "Adaptive delta modulation or Continuously variable slope delta modulation (CVSD) is a modification of DM in which the step size is not fixed. Rather, when several consecutive bits have the same direction value, the encoder and decoder assume that slope overload is occurring, and the step size becomes progressively larger.", "section_idx": 5, "section_name": "Adaptive delta modulation", "target_page_ids": [ 640949 ], "anchor_spans": [ [ 29, 73 ] ] }, { "plaintext": "Otherwise, the step size becomes gradually smaller over time. ADM reduces slope error, at the expense of increasing quantizing error. This error can be reduced by using a low-pass filter. ADM provides robust performance in the presence of bit errors meaning error detection and correction are not typically used in an ADM radio design, it is this very useful technique that allows for adaptive-delta-modulation.", "section_idx": 5, "section_name": "Adaptive delta modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Contemporary applications of Delta Modulation includes, but is not limited to, recreating legacy synthesizer waveforms. With the increasing availability of FPGAs and game-related ASICs, sample rates are easily controlled so as to avoid slope overload and granularity issues. For example, the C64DTV used a 32MHz sample rate, providing ample dynamic range to recreate the SID output to acceptable levels.", "section_idx": 6, "section_name": "Applications", "target_page_ids": [ 952151 ], "anchor_spans": [ [ 294, 300 ] ] }, { "plaintext": "Delta Modulation was used by Satellite Business Systems or SBS for its voice ports to provide long distance phone service to large domestic corporations with a significant inter-corporation communications need (such as IBM). This system was in service throughout the 1980s. The voice ports used digitally implemented 24kbit/s delta modulation with Voice Activity Compression (VAC) and echo suppressors to control the half second echo path through the satellite. They performed formal listening tests to verify the 24kbit/s delta modulator achieved full voice quality with no discernible degradation as compared to a high quality phone line or the standard 64kbit/s μ-law companded PCM. This provided an eight to three improvement in satellite channel capacity. IBM developed the Satellite Communications Controller and the voice port functions.", "section_idx": 7, "section_name": "SBS Application 24 kbps delta modulation", "target_page_ids": [ 2262244, 42401451, 41382, 40927 ], "anchor_spans": [ [ 29, 55 ], [ 387, 402 ], [ 668, 673 ], [ 674, 683 ] ] }, { "plaintext": "The original proposal in 1974, used a state-of-the-art 24kbit/s delta modulator with a single integrator and a Shindler Compander modified for gain error recovery. This proved to have less than full phone line speech quality. In 1977, one engineer with two assistants in the IBM Research Triangle Park, NC laboratory was assigned to improve the quality.", "section_idx": 7, "section_name": "SBS Application 24 kbps delta modulation", "target_page_ids": [ 371708 ], "anchor_spans": [ [ 281, 303 ] ] }, { "plaintext": "The final implementation replaced the integrator with a Predictor implemented with a two pole complex pair low-pass filter designed to approximate the long term average speech spectrum. The theory was that ideally the integrator should be a predictor designed to match the signal spectrum. A nearly perfect Shindler Compander replaced the modified version. It was found the modified compander resulted in a less than perfect step size at most signal levels and the fast gain error recovery increased the noise as determined by actual listening tests as compared to simple signal to noise measurements. The final compander achieved a very mild gain error recovery due to the natural truncation rounding error caused by twelve bit arithmetic.", "section_idx": 7, "section_name": "SBS Application 24 kbps delta modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The complete function of delta modulation, VAC and Echo Control for six ports was implemented in a single digital integrated circuit chip with twelve bit arithmetic. A single digital-to-analog converter (DAC) was shared by all six ports providing voltage compare functions for the modulators and feeding sample and hold circuits for the demodulator outputs. A single card held the chip, DAC and all the analog circuits for the phone line interface including transformers.", "section_idx": 7, "section_name": "SBS Application 24 kbps delta modulation", "target_page_ids": [ 92943 ], "anchor_spans": [ [ 176, 203 ] ] }, { "plaintext": " Adaptive differential pulse-code modulation", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 20568066 ], "anchor_spans": [ [ 1, 44 ] ] }, { "plaintext": " Analog-to-digital converter (ADC)", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 40367 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Codec", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 6660 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " Pulse-code modulation", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 25513330 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Pulse-density modulation", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 31980229 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Delta-sigma modulation", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 1745452 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Direct Stream Digital", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 309527 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Delta Modulator", "section_idx": 10, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Digital_signal_processing" ]

[ "Δ-modulation", "DM" ]

[ { "plaintext": "In telecommunication, a demand assignment is a method which several users share access to a communication channel on a real-time basis, i.e., a user needing to communicate with another user on the same network requests the required circuit, uses it, and when the call is finished, the circuit is released, making the circuit available to other users. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 7667814, 156700, 2052479, 46545, 346001, 406703 ], "anchor_spans": [ [ 3, 20 ], [ 74, 86 ], [ 92, 113 ], [ 144, 148 ], [ 202, 209 ], [ 232, 239 ], [ 263, 267 ] ] }, { "plaintext": "Demand assignment is similar to conventional telephone switching, in which common trunks are provided for many users, on a demand basis, through a limited-size trunk group.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26668156, 593233 ], "anchor_spans": [ [ 45, 64 ], [ 160, 171 ] ] }, { "plaintext": "Time-assignment speech interpolation", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 41792 ], "anchor_spans": [ [ 0, 36 ] ] } ]

[ "Teletraffic" ]

[]

[ { "plaintext": "In telecommunication, electronics and the electrical power industry, the term demand factor is used to refer to the fractional amount of some quantity being used relative to the maximum amount that could be used by the same system. The demand factor is always less than or equal to one. As the amount of demand is a time dependent quantity so is the demand factor.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 9663, 277750 ], "anchor_spans": [ [ 3, 20 ], [ 22, 33 ], [ 42, 67 ] ] }, { "plaintext": "The demand factor is often implicitly averaged over time when the time period of demand is understood by the context.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In electrical engineering the demand factor is taken as a time independent quantity where the numerator is taken as the maximum demand in the specified time period instead of the averaged or instantaneous demand.", "section_idx": 1, "section_name": "Electrical engineering", "target_page_ids": [ 9531 ], "anchor_spans": [ [ 3, 25 ] ] }, { "plaintext": "This is the peak in the load profile divided by the full load of the device.", "section_idx": 1, "section_name": "Electrical engineering", "target_page_ids": [ 4490333 ], "anchor_spans": [ [ 24, 36 ] ] }, { "plaintext": "Example:", "section_idx": 1, "section_name": "Electrical engineering", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "If a residence has equipment which could draw 6,000 W when all equipment was drawing a full load, drew a maximum of 3,000 W in a specified time, then the demand factor = 3,000 W / 6,000 W = 0.5", "section_idx": 1, "section_name": "Electrical engineering", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This quantity is relevant when trying to establish the amount of load for which a system should be rated. In the above example, it would be unlikely that the system would be rated to 6,000 W, even though there may be a slight possibility that this amount of power can be drawn. This is closely related to the load factor which is the average load divided by the peak load in a specified time period.", "section_idx": 1, "section_name": "Electrical engineering", "target_page_ids": [ 18254249 ], "anchor_spans": [ [ 309, 320 ] ] }, { "plaintext": " Capacity factor", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 3957510 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " List of energy storage projects", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 38861135 ], "anchor_spans": [ [ 1, 32 ] ] }, { "plaintext": " Load factor (electrical)", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 18254249 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Diversity factor", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 8499785 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Utilization factor", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 25777123 ], "anchor_spans": [ [ 1, 19 ] ] } ]

[ "Power_engineering" ]

[]

[ { "plaintext": "In telecommunication, the term demand load can have the following meanings: ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": " In general, the total power required by a facility. The demand load is the sum of the operational load (including any tactical load) and nonoperational demand loads. It is determined by applying the proper demand factor to each of the connected loads and a diversity factor to the sum total. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3270043, 41132, 3462904, 41017, 8499785 ], "anchor_spans": [ [ 23, 28 ], [ 43, 51 ], [ 64, 68 ], [ 207, 220 ], [ 258, 274 ] ] }, { "plaintext": " At a communications center, the power required by all automatic switching, synchronous, and terminal equipment (operated simultaneously on-line or in standby), control and keying equipment, plus lighting, ventilation, and air- conditioning equipment required to maintain full continuity of communications. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40916, 26668156, 28738, 41786, 4739163, 12481202, 40942 ], "anchor_spans": [ [ 6, 27 ], [ 65, 74 ], [ 76, 87 ], [ 93, 111 ], [ 151, 158 ], [ 173, 179 ], [ 228, 250 ] ] }, { "plaintext": " The power required for ventilating equipment, shop lighting, and other support items that may be operated simultaneously with the technical load. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The sum of the technical demand and nontechnical demand loads of an operating facility. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telecommunications_engineering" ]

[]

[ { "plaintext": "In telecommunication, desensitation is the reduction of desired signal gain as a result of receiver reaction to an undesired signal. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 41703, 41968 ], "anchor_spans": [ [ 3, 20 ], [ 64, 70 ], [ 71, 75 ] ] }, { "plaintext": "The gain reduction is generally due to overload of some portion of the receiver (e.g., the automatic gain control circuitry) resulting in suppression of the desired signal because the receiver will no longer respond linearly to incremental changes in input voltage.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 15235947, 234062 ], "anchor_spans": [ [ 39, 47 ], [ 91, 113 ] ] } ]

[ "Telecommunications_engineering" ]

[]

[ { "plaintext": "Design objective (DO): In communications systems, a desired performance characteristic for communications circuits and equipment that is based on engineering analyses, but (a) is not considered feasible to mandate in a standard, or (b) has not been tested. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 27065 ], "anchor_spans": [ [ 27, 41 ], [ 220, 228 ] ] }, { "plaintext": "DOs are used because applicable systems standards are not in existence. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Examples of reasons for designating a performance characteristic as a DO rather than as a standard are (a) it may be bordering on an advancement in the state of the art, (b) the requirement may not have been fully confirmed by measurement or experience with operating circuits, and (c) it may not have been demonstrated that the requirement can be met considering other constraints, such as cost and size. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A DO is sometimes established in a standard for developmental consideration. A DO may also specify a performance characteristic used in the preparation of specifications for development or procurement of new equipment or systems.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 763365 ], "anchor_spans": [ [ 189, 200 ] ] }, { "plaintext": "Design is the process of formulation of a plan for satisfaction of human needs", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telecommunications_engineering" ]

[]

[ { "plaintext": "A detector is a device capable of registering a specific substance or physical phenomenon.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 235757 ], "anchor_spans": [ [ 2, 10 ] ] }, { "plaintext": "Detector may also refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Detector (radio), a device that recovers information from a modulated wave", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 4529151 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Detector (film), a 2000 Norwegian film", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 13532838 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " USS Detector, two United States Navy ships", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 13295826 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " , was a coastal minesweeper launched 29 May 1941", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 12974078 ], "anchor_spans": [ [ 9, 28 ] ] }, { "plaintext": " , was a minesweeper launched 5 December 1952", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[]

[]

[ { "plaintext": "In telecommunications, deterministic routing is the advance determination of the routes between given pairs of nodes. Examples:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "In a network where routing is controlled by a telephone switch or network switch, switching in which the routes between given pairs of nodes are pre-programmed, i.e., are determined, in advance of transmission. The routes used to complete a given call through a network are identified, in advance of transmission, in routing tables maintained in each switch database. The tables assign the trunks that are to be used to reach each switch code, area code, and International Access Prefix (IAP), usually with one or two alternate routes. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26668156, 40614, 609152, 346001, 25750, 40614, 8377, 5225 ], "anchor_spans": [ [ 46, 62 ], [ 66, 80 ], [ 197, 209 ], [ 247, 251 ], [ 317, 324 ], [ 351, 357 ], [ 358, 366 ], [ 438, 442 ] ] }, { "plaintext": "In a non-switched network, the routes used to send a given message through the network are identified in advance in routing tables maintained in a database.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41367 ], "anchor_spans": [ [ 59, 66 ] ] } ]

[ "Telephone_exchanges", "Telecommunications_engineering" ]

[]

[ { "plaintext": "Pulse dialing is a signaling technology in telecommunications in which a direct current local loop circuit is interrupted according to a defined coding system for each signal transmitted, usually a digit. This lends the method the often used name loop disconnect dialing. In the most common variant of pulse dialing, decadic dialing, each of the ten Arabic numerals are encoded in a sequence of up to ten pulses. The most common version decodes the digits 1 through 9, as one to nine pulses, respectively, and the digit 0 as ten pulses. Historically, the most common device to produce such pulse trains is the rotary dial of the telephone, lending the technology another name, rotary dialing.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41703, 33094374, 59602, 5225, 1786, 527784, 1615818, 25960, 30003 ], "anchor_spans": [ [ 19, 28 ], [ 43, 61 ], [ 88, 98 ], [ 145, 151 ], [ 350, 365 ], [ 405, 411 ], [ 590, 601 ], [ 610, 621 ], [ 629, 638 ] ] }, { "plaintext": "The pulse repetition rate was historically determined based on the response time needed for electromechanical switching systems to operate reliably. Most telephone systems used the nominal rate of ten pulses per second, but operator dialing within and between central offices often used pulse rates up to twenty per second.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 28284 ], "anchor_spans": [ [ 92, 116 ] ] }, { "plaintext": "Automatic telephone exchange systems were developed in the late 19th and early 20th century. For identification, telephone subscribers were assigned a telephone number unique to each circuit. Various methods evolved to signal the desired destination telephone number for a telephone call directly dialed by the subscriber. An automatic switch-hook was designed by Hilborne Roosevelt.", "section_idx": 1, "section_name": "Early automatic exchanges", "target_page_ids": [ 26668156, 18790468, 16042064 ], "anchor_spans": [ [ 10, 28 ], [ 151, 167 ], [ 364, 382 ] ] }, { "plaintext": "The first commercial automatic telephone exchange, designed by Almon Brown Strowger, opened in La Porte, Indiana on 3 November 1892, and used two telegraph-type keys on the telephone, which had to be operated the correct number of times to control the vertical and horizontal relay magnets in the exchange. But the use of separate keys with separate conductors to the exchange was not practical. The most common signaling system became a system of using direct-current pulse trains generated in the telephone sets of subscribers by interrupting the single-pair wire loop of the telephone circuit.", "section_idx": 1, "section_name": "Early automatic exchanges", "target_page_ids": [ 163147, 112433, 21883857 ], "anchor_spans": [ [ 63, 83 ], [ 95, 103 ], [ 105, 112 ] ] }, { "plaintext": "Strowger also filed the first patent for a rotary dial in 1891. The first dials worked by direct, forward action. The pulses were sent as the user rotated the dial to the finger stop starting at a different position for each digit transmitted. Operating the dial error-free required smooth rotary motion of the finger wheel by the user, but was found as too unreliable. This mechanism was soon refined to include a recoil spring and a centrifugal governor to control the recoil speed. The user selected a digit to be dialed by inserting a finger into the corresponding hole and rotated the dial to the finger stop. When released from this position, the dial pulsing contacts were opened and closed repeatedly, thus interrupting the loop current in a pattern on the return to the home position. The exchange switch decoded the pattern for each digit thus transmitted by stepping relays or by accumulation in digit registers.", "section_idx": 2, "section_name": "Rotary dial", "target_page_ids": [ 23273, 84130 ], "anchor_spans": [ [ 30, 36 ], [ 435, 455 ] ] }, { "plaintext": "In the first electromechanical switching systems the current pulses generated by the rotary dial on the local loop directly operated electrical stepping switches at the central office. The mechanical nature of these relays generally limited the speed of operation, the pulsing rate, to ten pulses per second.", "section_idx": 3, "section_name": "Pulse rate and coding", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The specifications of the Bell System in the US required service personnel to adjust dials in customer stations to a precision of 9.5 to 10.5 pulses per second (PPS), but the tolerance of the switching equipment was generally between 8 and 11 PPS. The British (GPO, later Post Office Telecommunications) standard for Strowger switch exchanges has been ten impulses per second (allowable range 7 to 12) and a 66% break ratio (allowable range 63% to 72%)", "section_idx": 3, "section_name": "Pulse rate and coding", "target_page_ids": [ 5104719, 179918 ], "anchor_spans": [ [ 272, 302 ], [ 318, 333 ] ] }, { "plaintext": "In most switching systems one pulse is used for the digit 1, two pulses for 2, and so on, with ten pulses for the digit 0; this makes the code unary, excepting the digit 0. Exceptions to this are: Sweden, with one pulse for 0, two pulses for 1, and so on; and New Zealand with ten pulses for 0, nine pulses for 1, etc. Oslo, the capital city of Norway, used the New Zealand system, but the rest of the country did not. Systems that used this encoding of the ten digits in a sequence of up to ten pulses, are known as decadic dialing systems.", "section_idx": 3, "section_name": "Pulse rate and coding", "target_page_ids": [ 32316 ], "anchor_spans": [ [ 143, 148 ] ] }, { "plaintext": "Some switching systems used digit registers that doubled the allowable pulse rate up to twenty pulses per second, and the inter-digital pause could be reduced as the switch selection did not have to be completed during the pause. These included access lines to the Panel switch in the 1920s, Crossbar systems, the later version (7A2) of the Rotary system, and the earlier 1970s stored program control exchanges.", "section_idx": 3, "section_name": "Pulse rate and coding", "target_page_ids": [ 50350318, 17248101, 7092252 ], "anchor_spans": [ [ 265, 277 ], [ 341, 354 ], [ 378, 400 ] ] }, { "plaintext": "In some telephones, the pulses may be heard in the receiver as clicking sounds. However, in general, such effects were undesirable and telephone designers suppressed them by mechanical means with off-normal switches on the dial, or greatly attenuated them by electrical means with a varistor connected across the receiver.", "section_idx": 3, "section_name": "Pulse rate and coding", "target_page_ids": [ 142257 ], "anchor_spans": [ [ 283, 291 ] ] }, { "plaintext": "As pulse dialing is achieved by interruption of the local loop, it was possible to dial a telephone number by rapidly tapping, i.e. depressing, the switch hook the corresponding number of times for each digit at approximately ten taps per second. However, many telephone makers implemented a slow switch hook release to prevent rapid switching.", "section_idx": 4, "section_name": "Switch-hook dialing", "target_page_ids": [ 59602 ], "anchor_spans": [ [ 52, 62 ] ] }, { "plaintext": "In the United Kingdom, it used to be possible to make calls from coin-box phones (payphones) by tapping the switch hook without depositing coins. Unlawfully obtaining a free telephone call was deemed to be a criminal offence abstracting electricity from the General Post Office, which operated the telephone system and several cases were prosecuted.", "section_idx": 4, "section_name": "Switch-hook dialing", "target_page_ids": [ 163387, 32786242, 23310800 ], "anchor_spans": [ [ 82, 90 ], [ 225, 248 ], [ 258, 277 ] ] }, { "plaintext": "In popular culture, tapping was used in the film Red Dragon as a way for prisoner Hannibal Lecter to dial out on a phone with no dialling mechanism. The same technique was also used by the character Phantom Phreak in the film Hackers.", "section_idx": 4, "section_name": "Switch-hook dialing", "target_page_ids": [ 698242, 165684, 40852758 ], "anchor_spans": [ [ 49, 59 ], [ 82, 97 ], [ 226, 233 ] ] }, { "plaintext": "It was recognized as early as the 1940s that dialing could be faster and more accurate with push buttons, but this was too unreliable in customer trials until transistors transformed the industry. In 1963, the Bell System introduced to the public dual-tone multi-frequency (DTMF) technology under the name Touch-Tone, which was a trademark in the U.S. until 1984. The Touch-Tone system used push-button telephones. In the decades after 1963, rotary dials were gradually phased out on new telephone models in favor of keypads and the primary dialing method to the central office became touchtone dialing, but most central office systems still support rotary telephones today. Some keypad telephones have a switch or configuration method for the selection of tone or pulse dialing.", "section_idx": 5, "section_name": "Successors", "target_page_ids": [ 8488, 26046623 ], "anchor_spans": [ [ 247, 272 ], [ 391, 412 ] ] }, { "plaintext": "Mobile telephones and most voice-over-IP systems use out-of-band signaling and do not send any digits until the entire number has been keyed by the user. Many VoIP systems are based on the Session Initiation Protocol (SIP), which uses a form of Uniform Resource Identifiers (URI) for addressing, instead of digits alone.", "section_idx": 5, "section_name": "Successors", "target_page_ids": [ 19644137, 75028, 41703, 28684, 32146 ], "anchor_spans": [ [ 0, 16 ], [ 27, 40 ], [ 53, 74 ], [ 189, 216 ], [ 245, 272 ] ] }, { "plaintext": " Strowger switch", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 179918 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Federal Standard 1037C", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 37310 ], "anchor_spans": [ [ 1, 23 ] ] } ]

[ "Obsolete_technologies", "Telephony_signals" ]

[]

[ { "plaintext": "In electromagnetism, a dielectric (or dielectric material or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor, because they have no loosely bound, or free, electrons that may drift through the material, but instead they shift, only slightly, from their average equilibrium positions, causing dielectric polarisation. Because of dielectric polarisation, positive charges are displaced in the direction of the field and negative charges shift in the direction opposite to the field (for example, if the field is moving parallel to the positive x axis, the negative charges will shift in the negative x direction). This creates an internal electric field that reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarised, but also reorient so that their symmetry axes align to the field.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9532, 15066, 1237777, 41092, 9804, 198984, 698648, 5993, 701096 ], "anchor_spans": [ [ 3, 19 ], [ 86, 106 ], [ 119, 128 ], [ 143, 157 ], [ 218, 233 ], [ 285, 305 ], [ 524, 547 ], [ 947, 953 ], [ 1040, 1053 ] ] }, { "plaintext": "The study of dielectric properties concerns storage and dissipation of electric and magnetic energy in materials. Dielectrics are important for explaining various phenomena in electronics, optics, solid-state physics and cell biophysics.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 23971781, 9663, 22483, 102847, 42400646 ], "anchor_spans": [ [ 84, 99 ], [ 176, 187 ], [ 189, 195 ], [ 197, 216 ], [ 221, 236 ] ] }, { "plaintext": "Although the term insulator implies low electrical conduction, dielectric typically means materials with a high polarisability. The latter is expressed by a number called the relative permittivity. The term insulator is generally used to indicate electrical obstruction while the term dielectric is used to indicate the energy storing capacity of the material (by means of polarisation). A common example of a dielectric is the electrically insulating material between the metallic plates of a capacitor. The polarisation of the dielectric by the applied electric field increases the capacitor's surface charge for the given electric field strength.", "section_idx": 1, "section_name": "Terminology", "target_page_ids": [ 15066, 61580, 1237777, 53781, 24130, 4932111 ], "anchor_spans": [ [ 18, 27 ], [ 40, 61 ], [ 112, 126 ], [ 175, 196 ], [ 320, 326 ], [ 494, 503 ] ] }, { "plaintext": "The term dielectric was coined by William Whewell (from dia + electric) in response to a request from Michael Faraday. A perfect dielectric is a material with zero electrical conductivity (cf. perfect conductor infinite electrical conductivity), thus exhibiting only a displacement current; therefore it stores and returns electrical energy as if it were an ideal capacitor.", "section_idx": 1, "section_name": "Terminology", "target_page_ids": [ 205488, 19727, 1250078, 2635006, 555119 ], "anchor_spans": [ [ 34, 49 ], [ 102, 117 ], [ 189, 192 ], [ 193, 210 ], [ 269, 289 ] ] }, { "plaintext": "The electric susceptibility χe of a dielectric material is a measure of how easily it polarises in response to an electric field. This, in turn, determines the electric permittivity of the material and thus influences many other phenomena in that medium, from the capacitance of capacitors to the speed of light.", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [ 799876, 698648, 53933, 4932111, 28736 ], "anchor_spans": [ [ 4, 27 ], [ 86, 95 ], [ 169, 181 ], [ 279, 288 ], [ 297, 311 ] ] }, { "plaintext": "It is defined as the constant of proportionality (which may be a tensor) relating an electric field E to the induced dielectric polarisation density P such that", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [ 29965 ], "anchor_spans": [ [ 65, 71 ] ] }, { "plaintext": "where ε0 is the electric permittivity of free space.", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [ 2582879 ], "anchor_spans": [ [ 16, 51 ] ] }, { "plaintext": "The susceptibility of a medium is related to its relative permittivity εr by", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "So in the case of a vacuum,", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The electric displacement D is related to the polarisation density P by", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [ 1191101 ], "anchor_spans": [ [ 4, 25 ] ] }, { "plaintext": "In general, a material cannot polarise instantaneously in response to an applied field. The more general formulation as a function of time is", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "That is, the polarisation is a convolution of the electric field at previous times with time-dependent susceptibility given by χe(Δt). The upper limit of this integral can be extended to infinity as well if one defines for . An instantaneous response corresponds to Dirac delta function susceptibility .", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [ 7519, 37021 ], "anchor_spans": [ [ 31, 42 ], [ 267, 287 ] ] }, { "plaintext": "It is more convenient in a linear system to take the Fourier transform and write this relationship as a function of frequency. Due to the convolution theorem, the integral becomes a simple product,", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [ 52247, 53268 ], "anchor_spans": [ [ 53, 70 ], [ 138, 157 ] ] }, { "plaintext": "The susceptibility (or equivalently the permittivity) is frequency dependent. The change of susceptibility with respect to frequency characterises the dispersion properties of the material.", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [ 172333 ], "anchor_spans": [ [ 151, 161 ] ] }, { "plaintext": "Moreover, the fact that the polarisation can only depend on the electric field at previous times (i.e., for ), a consequence of causality, imposes Kramers–Kronig constraints on the real and imaginary parts of the susceptibility χe(ω).", "section_idx": 2, "section_name": "Electric susceptibility", "target_page_ids": [ 37196, 2481686 ], "anchor_spans": [ [ 129, 138 ], [ 148, 174 ] ] }, { "plaintext": "In the classical approach to the dielectric, the material is made up of atoms. Each atom consists of a cloud of negative charge (electrons) bound to and surrounding a positive point charge at its center. In the presence of an electric field, the charge cloud is distorted, as shown in the top right of the figure.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This can be reduced to a simple dipole using the superposition principle. A dipole is characterised by its dipole moment, a vector quantity shown in the figure as the blue arrow labeled M. It is the relationship between the electric field and the dipole moment that gives rise to the behaviour of the dielectric. (Note that the dipole moment points in the same direction as the electric field in the figure. This isn't always the case, and is a major simplification, but is true for many materials.)", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 8378, 1201321, 30876071 ], "anchor_spans": [ [ 32, 38 ], [ 49, 72 ], [ 107, 120 ] ] }, { "plaintext": "When the electric field is removed the atom returns to its original state. The time required to do so is the so-called relaxation time; an exponential decay.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 1780263 ], "anchor_spans": [ [ 119, 129 ] ] }, { "plaintext": "This is the essence of the model in physics. The behaviour of the dielectric now depends on the situation. The more complicated the situation, the richer the model must be to accurately describe the behaviour. Important questions are:", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Is the electric field constant or does it vary with time? At what rate?", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Does the response depend on the direction of the applied field (isotropy of the material)?", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 14865 ], "anchor_spans": [ [ 64, 72 ] ] }, { "plaintext": "Is the response the same everywhere (homogeneity of the material)?", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 2578746 ], "anchor_spans": [ [ 37, 48 ] ] }, { "plaintext": "Do any boundaries or interfaces have to be taken into account?", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Is the response linear with respect to the field, or are there nonlinearities?", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 722503, 146103 ], "anchor_spans": [ [ 16, 22 ], [ 63, 77 ] ] }, { "plaintext": "The relationship between the electric field E and the dipole moment M gives rise to the behaviour of the dielectric, which, for a given material, can be characterised by the function F defined by the equation:", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "When both the type of electric field and the type of material have been defined, one then chooses the simplest function F that correctly predicts the phenomena of interest. Examples of phenomena that can be so modelled include:", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Refractive index", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 25880 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Group velocity dispersion", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 681625 ], "anchor_spans": [ [ 0, 25 ] ] }, { "plaintext": "Birefringence", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 174412 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Self-focusing", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 12017057 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Harmonic generation", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 8840378 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Dipolar polarisation is a polarisation that is either inherent to polar molecules (orientation polarisation), or can be induced in any molecule in which the asymmetric distortion of the nuclei is possible (distortion polarisation). Orientation polarisation results from a permanent dipole, e.g., that arising from the 104.45° angle between the asymmetric bonds between oxygen and hydrogen atoms in the water molecule, which retains polarisation in the absence of an external electric field. The assembly of these dipoles forms a macroscopic polarisation.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 361038 ], "anchor_spans": [ [ 66, 80 ] ] }, { "plaintext": "When an external electric field is applied, the distance between charges within each permanent dipole, which is related to chemical bonding, remains constant in orientation polarisation; however, the direction of polarisation itself rotates. This rotation occurs on a timescale that depends on the torque and surrounding local viscosity of the molecules. Because the rotation is not instantaneous, dipolar polarisations lose the response to electric fields at the highest frequencies. A molecule rotates about 1 radian per picosecond in a fluid, thus this loss occurs at about 1011 Hz (in the microwave region). The delay of the response to the change of the electric field causes friction and heat.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 5993, 30400, 18963754, 11062 ], "anchor_spans": [ [ 123, 136 ], [ 298, 304 ], [ 327, 336 ], [ 681, 689 ] ] }, { "plaintext": "When an external electric field is applied at infrared frequencies or less, the molecules are bent and stretched by the field and the molecular dipole moment changes. The molecular vibration frequency is roughly the inverse of the time it takes for the molecules to bend, and this distortion polarisation disappears above the infrared.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 15022 ], "anchor_spans": [ [ 46, 54 ] ] }, { "plaintext": "Ionic polarisation is polarisation caused by relative displacements between positive and negative ions in ionic crystals (for example, NaCl).", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 18963787, 42566, 80207 ], "anchor_spans": [ [ 98, 101 ], [ 106, 119 ], [ 135, 139 ] ] }, { "plaintext": "If a crystal or molecule consists of atoms of more than one kind, the distribution of charges around an atom in the crystal or molecule leans to positive or negative. As a result, when lattice vibrations or molecular vibrations induce relative displacements of the atoms, the centers of positive and negative charges are also displaced. The locations of these centers are affected by the symmetry of the displacements. When the centers don't correspond, polarisation arises in molecules or crystals. This polarisation is called ionic polarisation.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Ionic polarisation causes the ferroelectric effect as well as dipolar polarisation. The ferroelectric transition, which is caused by the lining up of the orientations of permanent dipoles along a particular direction, is called an order-disorder phase transition. The transition caused by ionic polarisations in crystals is called a displacive phase transition.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 44708 ], "anchor_spans": [ [ 30, 50 ] ] }, { "plaintext": "Ionic polarisation enables the production of energy-rich compounds in cells (the proton pump in mitochondria) and, at the plasma membrane, the establishment of the resting potential, energetically unfavourable transport of ions, and cell-to-cell communication (the Na+/K+-ATPase).", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 92441, 19588, 33051527, 777072, 182379 ], "anchor_spans": [ [ 81, 92 ], [ 96, 108 ], [ 122, 137 ], [ 164, 181 ], [ 265, 278 ] ] }, { "plaintext": "All cells in animal body tissues are electrically polarised – in other words, they maintain a voltage difference across the cell's plasma membrane, known as the membrane potential. This electrical polarisation results from a complex interplay between ion transporters and ion channels.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 33051527, 563161, 4575803, 15303 ], "anchor_spans": [ [ 131, 146 ], [ 161, 179 ], [ 251, 267 ], [ 272, 284 ] ] }, { "plaintext": "In neurons, the types of ion channels in the membrane usually vary across different parts of the cell, giving the dendrites, axon, and cell body different electrical properties. As a result, some parts of the membrane of a neuron may be excitable (capable of generating action potentials), whereas others are not.", "section_idx": 3, "section_name": "Dielectric polarisation", "target_page_ids": [ 8131, 958, 1306158 ], "anchor_spans": [ [ 114, 122 ], [ 125, 129 ], [ 135, 144 ] ] }, { "plaintext": "In physics, dielectric dispersion is the dependence of the permittivity of a dielectric material on the frequency of an applied electric field. Because there is a lag between changes in polarisation and changes in the electric field, the permittivity of the dielectric is a complicated function of frequency of the electric field. Dielectric dispersion is very important for the applications of dielectric materials and for the analysis of polarisation systems.", "section_idx": 4, "section_name": "Dielectric dispersion", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This is one instance of a general phenomenon known as material dispersion: a frequency-dependent response of a medium for wave propagation.", "section_idx": 4, "section_name": "Dielectric dispersion", "target_page_ids": [ 172333 ], "anchor_spans": [ [ 54, 73 ] ] }, { "plaintext": "When the frequency becomes higher:", "section_idx": 4, "section_name": "Dielectric dispersion", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " dipolar polarisation can no longer follow the oscillations of the electric field in the microwave region around 1010 Hz;", "section_idx": 4, "section_name": "Dielectric dispersion", "target_page_ids": [ 20097, 14121 ], "anchor_spans": [ [ 89, 98 ], [ 118, 120 ] ] }, { "plaintext": " ionic polarisation and molecular distortion polarisation can no longer track the electric field past the infrared or far-infrared region around 1013 Hz, ;", "section_idx": 4, "section_name": "Dielectric dispersion", "target_page_ids": [ 15022 ], "anchor_spans": [ [ 106, 114 ] ] }, { "plaintext": " electronic polarisation loses its response in the ultraviolet region around 1015 Hz.", "section_idx": 4, "section_name": "Dielectric dispersion", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the frequency region above ultraviolet, permittivity approaches the constant ε0 in every substance, where ε0 is the permittivity of the free space. Because permittivity indicates the strength of the relation between an electric field and polarisation, if a polarisation process loses its response, permittivity decreases.", "section_idx": 4, "section_name": "Dielectric dispersion", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Dielectric relaxation is the momentary delay (or lag) in the dielectric constant of a material. This is usually caused by the delay in molecular polarisation with respect to a changing electric field in a dielectric medium (e.g., inside capacitors or between two large conducting surfaces). Dielectric relaxation in changing electric fields could be considered analogous to hysteresis in changing magnetic fields (e.g., in inductor or transformer cores). Relaxation in general is a delay or lag in the response of a linear system, and therefore dielectric relaxation is measured relative to the expected linear steady state (equilibrium) dielectric values. The time lag between electrical field and polarisation implies an irreversible degradation of Gibbs free energy.", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 53781, 198984, 147003, 36563, 14896, 30906, 1516916, 722503, 238181 ], "anchor_spans": [ [ 61, 80 ], [ 269, 279 ], [ 374, 384 ], [ 397, 411 ], [ 423, 431 ], [ 435, 446 ], [ 447, 452 ], [ 516, 529 ], [ 751, 768 ] ] }, { "plaintext": "In physics, dielectric relaxation refers to the relaxation response of a dielectric medium to an external, oscillating electric field. This relaxation is often described in terms of permittivity as a function of frequency, which can, for ideal systems, be described by the Debye equation. On the other hand, the distortion related to ionic and electronic polarisation shows behaviour of the resonance or oscillator type. The character of the distortion process depends on the structure, composition, and surroundings of the sample.", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 22939, 10779, 41660, 22522 ], "anchor_spans": [ [ 3, 10 ], [ 212, 221 ], [ 391, 400 ], [ 404, 414 ] ] }, { "plaintext": "Debye relaxation is the dielectric relaxation response of an ideal, noninteracting population of dipoles to an alternating external electric field. It is usually expressed in the complex permittivity ε of a medium as a function of the field's angular frequency ω:", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 199829 ], "anchor_spans": [ [ 243, 260 ] ] }, { "plaintext": "where ε∞ is the permittivity at the high frequency limit, where εs is the static, low frequency permittivity, and τ is the characteristic relaxation time of the medium. Separating into the real part and the imaginary part of the complex dielectric permittivity yields:", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 1780263 ], "anchor_spans": [ [ 139, 154 ] ] }, { "plaintext": "Note that the above equation for is sometimes written with in the denominator due to an ongoing sign convention ambiguity whereby many sources represent the time dependence of the complex electric field with whereas others use . In the former convention, the functions and representing real and imaginary parts are given by whereas in the latter convention . The above equation uses the latter convention. ", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The dielectric loss is also represented by the loss tangent:", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This relaxation model was introduced by and named after the physicist Peter Debye (1913). It is characteristic for dynamic polarisation with only one relaxation time.", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 37067 ], "anchor_spans": [ [ 70, 81 ] ] }, { "plaintext": "Cole–Cole equation This equation is used when the dielectric loss peak shows symmetric broadening.", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 4481005 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "Cole–Davidson equation This equation is used when the dielectric loss peak shows asymmetric broadening.", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 70105931 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Havriliak–Negami relaxation This equation considers both symmetric and asymmetric broadening.", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 1914171 ], "anchor_spans": [ [ 0, 27 ] ] }, { "plaintext": "Kohlrausch–Williams–Watts function Fourier transform of stretched exponential function.", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 6262575 ], "anchor_spans": [ [ 56, 86 ] ] }, { "plaintext": "Curie–von Schweidler law This shows the response of dielectrics to an applied DC field to behave according to a power law, which can be expressed as an integral over weighted exponential functions..", "section_idx": 5, "section_name": "Dielectric relaxation", "target_page_ids": [ 53476992 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Paraelectricity is the nominal behaviour of dielectrics when the dielectric permittivity tensor is proportional to the unit matrix, i.e., an applied electric field causes polarisation and/or alignment of dipoles only parallel to the applied electric field. Contrary to the analogy with a paramagnetic material, no permanent electric dipole needs to exist in a paraelectric material. Removal of the fields results in the dipolar polarisation returning to zero. The mechanisms that causes paraelectric behaviour are distortion of individual ions (displacement of the electron cloud from the nucleus) and polarisation of molecules or combinations of ions or defects.", "section_idx": 6, "section_name": "Paraelectricity", "target_page_ids": [ 41092, 30876071, 18963787 ], "anchor_spans": [ [ 149, 163 ], [ 324, 339 ], [ 539, 543 ] ] }, { "plaintext": "Paraelectricity can occur in crystal phases where electric dipoles are unaligned and thus have the potential to align in an external electric field and weaken it.", "section_idx": 6, "section_name": "Paraelectricity", "target_page_ids": [ 6015, 41092 ], "anchor_spans": [ [ 29, 36 ], [ 133, 147 ] ] }, { "plaintext": "Most dielectric materials are paraelectrics. A specific example of a paraelectric material of high dielectric constant is strontium titanate.", "section_idx": 6, "section_name": "Paraelectricity", "target_page_ids": [ 579645 ], "anchor_spans": [ [ 122, 140 ] ] }, { "plaintext": "The LiNbO3 crystal is ferroelectric below 1430 K, and above this temperature it transforms into a disordered paraelectric phase. Similarly, other perovskites also exhibit paraelectricity at high temperatures.", "section_idx": 6, "section_name": "Paraelectricity", "target_page_ids": [ 3243489, 44708, 19593121, 19290728 ], "anchor_spans": [ [ 4, 10 ], [ 22, 35 ], [ 47, 48 ], [ 146, 156 ] ] }, { "plaintext": "Paraelectricity has been explored as a possible refrigeration mechanism; polarising a paraelectric by applying an electric field under adiabatic process conditions raises the temperature, while removing the field lowers the temperature. A heat pump that operates by polarising the paraelectric, allowing it to return to ambient temperature (by dissipating the extra heat), bringing it into contact with the object to be cooled, and finally depolarising it, would result in refrigeration.", "section_idx": 6, "section_name": "Paraelectricity", "target_page_ids": [ 1419, 68316 ], "anchor_spans": [ [ 135, 152 ], [ 239, 248 ] ] }, { "plaintext": "Tunable dielectrics are insulators whose ability to store electrical charge changes when a voltage is applied.", "section_idx": 7, "section_name": "Tunability", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Generally, strontium titanate () is used for devices operating at low temperatures, while barium strontium titanate () substitutes for room temperature devices. Other potential materials include microwave dielectrics and carbon nanotube (CNT) composites.", "section_idx": 7, "section_name": "Tunability", "target_page_ids": [ 579645, 184306 ], "anchor_spans": [ [ 11, 29 ], [ 90, 115 ] ] }, { "plaintext": "In 2013, multi-sheet layers of strontium titanate interleaved with single layers of strontium oxide produced a dielectric capable of operating at up to 125 GHz. The material was created via molecular beam epitaxy. The two have mismatched crystal spacing that produces strain within the strontium titanate layer that makes it less stable and tunable.", "section_idx": 7, "section_name": "Tunability", "target_page_ids": [ 2616890, 450052 ], "anchor_spans": [ [ 84, 99 ], [ 190, 212 ] ] }, { "plaintext": "Systems such as have a paraelectric–ferroelectric transition just below ambient temperature, providing high tunability. Films suffer significant losses arising from defects.", "section_idx": 7, "section_name": "Tunability", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Commercially manufactured capacitors typically use a solid dielectric material with high permittivity as the intervening medium between the stored positive and negative charges. This material is often referred to in technical contexts as the capacitor dielectric.", "section_idx": 8, "section_name": "Applications", "target_page_ids": [ 18993816 ], "anchor_spans": [ [ 53, 58 ] ] }, { "plaintext": "The most obvious advantage to using such a dielectric material is that it prevents the conducting plates, on which the charges are stored, from coming into direct electrical contact. More significantly, however, a high permittivity allows a greater stored charge at a given voltage. This can be seen by treating the case of a linear dielectric with permittivity ε and thickness d between two conducting plates with uniform charge density σε. In this case the charge density is given by", "section_idx": 8, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "and the capacitance per unit area by", "section_idx": 8, "section_name": "Applications", "target_page_ids": [ 140711 ], "anchor_spans": [ [ 8, 19 ] ] }, { "plaintext": "From this, it can easily be seen that a larger ε leads to greater charge stored and thus greater capacitance.", "section_idx": 8, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Dielectric materials used for capacitors are also chosen such that they are resistant to ionisation. This allows the capacitor to operate at higher voltages before the insulating dielectric ionises and begins to allow undesirable current.", "section_idx": 8, "section_name": "Applications", "target_page_ids": [ 59611 ], "anchor_spans": [ [ 89, 99 ] ] }, { "plaintext": "A dielectric resonator oscillator (DRO) is an electronic component that exhibits resonance of the polarisation response for a narrow range of frequencies, generally in the microwave band. It consists of a \"puck\" of ceramic that has a large dielectric constant and a low dissipation factor. Such resonators are often used to provide a frequency reference in an oscillator circuit. An unshielded dielectric resonator can be used as a dielectric resonator antenna (DRA).", "section_idx": 8, "section_name": "Applications", "target_page_ids": [ 41660, 634785, 13333998 ], "anchor_spans": [ [ 81, 90 ], [ 270, 288 ], [ 432, 460 ] ] }, { "plaintext": "From 2002 to 2004, the United States Army Research Laboratory (ARL) conducted research on thin film technology. Barium strontium titanate (BST), a ferroelectric thin film, was studied for the fabrication of radio frequency and microwave components, such as voltage-controlled oscillators, tunable filters and phase shifters.", "section_idx": 8, "section_name": "Applications", "target_page_ids": [ 3678878 ], "anchor_spans": [ [ 37, 61 ] ] }, { "plaintext": "The research was part of an effort to provide the Army with highly-tunable, microwave-compatible materials for broadband electric-field tunable devices, which operate consistently in extreme temperatures. This work improved tunability of bulk barium strontium titanate, which is a thin film enabler for electronics components.", "section_idx": 8, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In a 2004 research paper, U.S. ARL researchers explored how small concentrations of acceptor dopants can dramatically modify the properties of ferroelectric materials such as BST.", "section_idx": 8, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Researchers \"doped\" BST thin films with magnesium, analyzing the \"structure, microstructure, surface morphology and film/substrate compositional quality\" of the result. The Mg doped BST films showed \"improved dielectric properties, low leakage current, and good tunability\", meriting potential for use in microwave tunable devices.", "section_idx": 8, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Dielectric materials can be solids, liquids, or gases. (A high vacuum can also be a useful, nearly lossless dielectric even though its relative dielectric constant is only unity.)", "section_idx": 9, "section_name": "Some practical dielectrics", "target_page_ids": [ 32502, 53781 ], "anchor_spans": [ [ 63, 69 ], [ 144, 163 ] ] }, { "plaintext": "Solid dielectrics are perhaps the most commonly used dielectrics in electrical engineering, and many solids are very good insulators. Some examples include porcelain, glass, and most plastics. Air, nitrogen and sulfur hexafluoride are the three most commonly used gaseous dielectrics.", "section_idx": 9, "section_name": "Some practical dielectrics", "target_page_ids": [ 167718, 12581, 26145195, 21175, 457036, 27689481 ], "anchor_spans": [ [ 156, 165 ], [ 167, 172 ], [ 183, 190 ], [ 198, 206 ], [ 211, 230 ], [ 264, 282 ] ] }, { "plaintext": "Industrial coatings such as Parylene provide a dielectric barrier between the substrate and its environment.", "section_idx": 9, "section_name": "Some practical dielectrics", "target_page_ids": [ 1897245, 4939491 ], "anchor_spans": [ [ 0, 18 ], [ 28, 36 ] ] }, { "plaintext": "Mineral oil is used extensively inside electrical transformers as a fluid dielectric and to assist in cooling. Dielectric fluids with higher dielectric constants, such as electrical grade castor oil, are often used in high voltage capacitors to help prevent corona discharge and increase capacitance.", "section_idx": 9, "section_name": "Some practical dielectrics", "target_page_ids": [ 212419, 30906, 172190, 1205325, 318352 ], "anchor_spans": [ [ 0, 11 ], [ 50, 61 ], [ 188, 198 ], [ 218, 230 ], [ 258, 274 ] ] }, { "plaintext": "Because dielectrics resist the flow of electricity, the surface of a dielectric may retain stranded excess electrical charges. This may occur accidentally when the dielectric is rubbed (the triboelectric effect). This can be useful, as in a Van de Graaff generator or electrophorus, or it can be potentially destructive as in the case of electrostatic discharge.", "section_idx": 9, "section_name": "Some practical dielectrics", "target_page_ids": [ 60933, 52642, 225270, 75049 ], "anchor_spans": [ [ 190, 210 ], [ 241, 264 ], [ 268, 281 ], [ 338, 361 ] ] }, { "plaintext": "Specially processed dielectrics, called electrets (which should not be confused with ferroelectrics), may retain excess internal charge or \"frozen in\" polarisation. Electrets have a semi-permanent electric field, and are the electrostatic equivalent to magnets. Electrets have numerous practical applications in the home and industry.", "section_idx": 9, "section_name": "Some practical dielectrics", "target_page_ids": [ 492429, 44708 ], "anchor_spans": [ [ 40, 48 ], [ 85, 98 ] ] }, { "plaintext": "Some dielectrics can generate a potential difference when subjected to mechanical stress, or (equivalently) change physical shape if an external voltage is applied across the material. This property is called piezoelectricity. Piezoelectric materials are another class of very useful dielectrics.", "section_idx": 9, "section_name": "Some practical dielectrics", "target_page_ids": [ 228107, 24975 ], "anchor_spans": [ [ 82, 88 ], [ 209, 225 ] ] }, { "plaintext": "Some ionic crystals and polymer dielectrics exhibit a spontaneous dipole moment, which can be reversed by an externally applied electric field. This behaviour is called the ferroelectric effect. These materials are analogous to the way ferromagnetic materials behave within an externally applied magnetic field. Ferroelectric materials often have very high dielectric constants, making them quite useful for capacitors.", "section_idx": 9, "section_name": "Some practical dielectrics", "target_page_ids": [ 6015, 23001, 44708, 11807 ], "anchor_spans": [ [ 11, 18 ], [ 24, 31 ], [ 173, 193 ], [ 236, 259 ] ] }, { "plaintext": "Classification of materials based on permittivity", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 53933 ], "anchor_spans": [ [ 0, 49 ] ] }, { "plaintext": "Paramagnetism", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 23750 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Clausius-Mossotti relation", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 826956 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "Dielectric absorption", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 34469840 ], "anchor_spans": [ [ 0, 21 ] ] }, { "plaintext": "Dielectric losses", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 7090506 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Dielectric strength", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 41027 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Dielectric spectroscopy", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 1894582 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "EIA Class 1 dielectric", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 9221221 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "EIA Class 2 dielectric", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 9221221 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "High-κ dielectric", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 2332464 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Low-κ dielectric", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 934064 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "leakage", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 24280173 ], "anchor_spans": [ [ 0, 7 ] ] }, { "plaintext": "Linear response function", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 8419626 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Metamaterial", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 906878 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "RC delay", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 540772 ], "anchor_spans": [ [ 0, 8 ] ] }, { "plaintext": "Rotational Brownian motion", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 20793410 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "Paschen's law – variation of Dielectric strength of gas related to pressure", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 614192 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Separator (electricity)", "section_idx": 10, "section_name": "See also", "target_page_ids": [ 30038658 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Feynman's lecture on dielectrics", "section_idx": 13, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Dielectric Sphere in an Electric Field", "section_idx": 13, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Dissemination of IT for the Promotion of Materials Science (DoITPoMS) Teaching and Learning Package \"Dielectric Materials\" from the University of Cambridge", "section_idx": 13, "section_name": "External links", "target_page_ids": [ 25978572 ], "anchor_spans": [ [ 132, 155 ] ] } ]

[ "Dielectrics", "Electric_and_magnetic_fields_in_matter" ]

[ "dielectric medium" ]