upstream RF signals. Upstream RF signals are combined within the device, converted from RF to optical wavelength by a laser and transmitted via optical fiber from the device to a cable operator HE or hub. Excerpt from ANSI/SCTE 87-1 2008, “Graphic Symbols For Cable Systems Part 1: HFC Symbols” 5/8-24 RF & AC Equipment Port, Female Equipment ports of this type are defined by ANSI/SCTE 91 2009, Specification for 5/8-24 RF & AC Equipment Port, Female. This specification serves as a recommended guideline for the physical dimensions of all female 5/8 – 24 equipment ports for RF and AC powering that are used in the 75 ohm RF broadband communications industry. 5/8-24 Plug, Male Adapters Also referred to as a “Stinger”. Coaxial cable connector employed to connect hybrid fiber coaxial (HFC) network transmission line optical nodes, trunk/bridger, and line extender (LE) amplifiers to low loss, large diameter coaxial cable. Male connectors of this type are defined by ANSI/SCTE 111 2010 Specification for 5/8-24 Plug, Male Adapters. This specification serves as a recommended guideline for the physical dimensions of 5/8 – 24 plug (male) hard-line adapters that are used as interconnects in the 75 ohm RF broadband communications industry. It is not the purpose of this standard to specify the details of manufacturing. This type of termination is also known as a “trunk and distribution” coaxial cable connector. 56Kbps Modems More appropriately called Pulse Code Modulation (PCM) Modems, these modems manipulate the way the telephone system works to send data to an analog “modem” type device at speeds of up to 56,000 bits per second (56Kbps). 56K modems work by using ISDN telephone equipment at one end of the connection to manipulate the PCM codes sent across the telephone network. When these PCM sample codes reach the Codec they are translated into a specific series of voltage changes that a PCM modem knows how to interpret. Data sent out by a 56Kbps modem is subject to the same physical restrictions of any modem, so its top “back channel” speed is 33.6Kbps. 56Kbps modems are built against the ITU-T V.90 or V.92 standards.
CODEC Coder-DECoder Coder-Decoder (CODEC) A function or device that performs compression and decompression, typically on voice or video streams. Codes Exchange (CODEX) A telecommunications Codex specifies how different binary values sent across the telephone network are translated to and from specific sample voltages. See also Codec. CODEX Codes Exchange COFDM Coded Orthogonal Frequency Division Modulation; OFDM used in conjunction with channel coding techniques. As the overhead of doing this in an already digital system is low, and the gains substantial, practical OFDM/DMT systems are all actually COFDM. Although highly complex, COFDM has high performance under even very challenging channel conditions. By combining the OFDM technique with error-correcting codes, adaptive equalization and reconfigurable modulation, COFDM has the following properties: resistant against link dispersion resistant against slowly changing phase distortion and fading resistant against frequency response nulls and constant frequency interference resistant against burst noise COFDM also generally has a nearly 'white' spectrum, giving it benign electromagnetic interference properties with respect to other signals. Some COFDM systems use some of the sub carriers to carry pilot signals, which are used for frequency synchronizations, as frequency shifts during the transmission using the main modulation/demodulation process transform into bit errors in the decoded data. In wide area broadcasting, receivers can benefit from receiving signals from several spatially dispersed transmitters simultaneously, since transmitters will only destructively interfere with each other on a limited number of subcarriers, whereas in general they will actually reinforce coverage over a wide area. This is very beneficial in many countries, as it permits the operation of national single frequency networks, and avoids the replication of program content on different carrier frequencies which is necessary with FM or other forms of radio broadcasting. Also, because effectively the bit rate is slowed down on each sub-carrier, the effects of "ghosting" are much reduced. Such single frequency networks utilize the available spectrum more effectively than existing analog radio networks. Coherent Communications
Decoder A device used to convert data by reversing the effect of previous coding. Decryption A procedure applied to ciphertext to translate it into plaintext. Decryption Key The key in the cryptographic algorithm to translate the ciphertext to plaintext. DECT Digital Enhanced Cordless Telecommunications Deemphasis Reinstatement of a uniform baseband frequency response following demodulation. De-Emphasis The restoration of a pre-emphasized signal wave to its original form (see Pre-Emphasis). Deep Well GaAs Processing of Gallium Arsenide (GaAs) based III-V semiconductor material to create a quantum well, rib, or trench within the material for use as a waveguide suitable for optical transmission. Schematic GaAs-AIGaAs Rib Waveguide, with loss mechanisms indicated: (1) epilayer roughness, (2) substrate leakage, (3) rib sidewall roughness, and (4) defect and impurity absorption. Rib width W, and height h are shown. Courtesy of IEEE Journal of Quantum Electronics, Volume 27, Number 3, March 1991, “Low-Loss III-V Semiconductor Optical Waveguides”, Robert J. Deri and Eli Kapon Delay The elapsed time between the instant when user information is submitted to the network and when it is received by the user at the other end. Delay Distortion Distortion resulting from non-uniform speed of transmission of the various frequency components of a signal; i.e., the various frequency components of the signal have different times of travel (delay) between the input and the output of a circuit. Also known as Group Delay Distortion.
Delay Spread An effect of multi-path for a digital interface in which multiple reflections of the same signal arrive at the receiver at different times, creating a noticeable degradation in signal quality. Demark The point of demarcation between equipment and facility or between outside plant facilities and premises distribution. Demodulation The extraction of the modulation or information from a radio-frequency current. Demographics Breakdown of television viewers by such factors as age, sex, income levels, education and race. Demultiplexer (DEMUX) A module that separates two or more signals previously combined by compatible multiplexing equipment. Multiplexer (MUX) – Demultiplexer (DEMUX) Diagram courtesy of Fiber Optics Info, Dense Wavelength Division Multiplexing (DWDM) A technology that provides, in fiber, the equivalent of frequency division multiplexing in metallic wire. Separate parallel channels are transmitted on a single fiber, with one wavelength for each channel. Current products enable 16 channels of 2.5Gb each for a total of 50Gb per fiber. DWDM can operate over existing single-mode fiber, and therefore reduce upgrade costs. DWDM permits transmission of closely spaced wavelengths in the 1550 nm region over a single optical fiber. Wavelength spacings are usually 100 GHz or 200 GHz which corresponds to 0.8 nm or 1.6 nm. DWDM bands include the C-Band, the and the L-Band. See also Coarse Wavelength Division Multiplexing (CWDM). DWDM Diagram courtesy of Fiber Optics Info, De-QPSK Differential Quadrature Phase Shift Keying DER Dynamic Extinction Ratio, ERRF; measured by applying an RF electrical signal at the RF input port of an optical intensity modulator, the DC bias voltage being tuned so as to set the modulator at the desired operating point (this operating point may be positive or negative quadrature, minimum, maximum or any other point of the transfer function depending on the application). ERRF is application dependent. For digital applications, the RF electrical
Digital Application Software Environment (DASE) A standard by ATSC addressing interactive television. Digital Audio Visual Council (DAVIC) DAVIC is an international consortium working on the development of standards for interactive television. Digital Certificate A binding between an entity's public key and one or more attributes relating to its identity, also known as a public key certificate. Digital Compression An engineering technique for converting a cable TV signal into a digital format which may then be processed in a manner that requires a smaller portion of spectrum for its transmission. This compressed format allows many channels to be carried in the bandwidth normally required for one signal. This format can also be easily stored and manipulated. Digital Enhanced Cordless Telecommunications (DECT) A European standard governing panEuropean digital mobile telephony. Specified in DVB MHP as a type of return channel network interface for use in receiving and transmitting IP packets. Digital Facility A switching or transmission facility designed specifically to handle digital signals. Digital Program Insertion (DPI) The digital splicing of one Moving Pictures Experts Group (MPEG) program (typically a commercial) into another based on digital 'cues' within the MPEG transport stream. Digital QAM In digital QAM, the input stream is divided into groups of bits based on the number of modulation states used. For example, in 8QAM, each three bits of input, which provides eight values (0-7) alters the phase and amplitude of the carrier to derive eight unique modulation states. In 64QAM, each six bits generates 64 modulation states; in 128QAM, each seven bits generates 128 states, and so on. See modulation. Digital Receiver Interface (DRI) A CableLabs-specified interface over Internet Protocol (IP) that protects cable operators' "harm-to-service" issues. These issues include ensuring that information like emergency alerts and set-up screens are displayed, that there is sufficient bandwidth to deliver the service, that the content is not altered, etc. It also provides commands to enable communication of information between an OpenCable™ unidirectional receiver (OCUR) and a home media server (HMS).
division multiplexing (TDM) & Ethernet EPON (Ethernet PON) IEEE 802.3ah 100 Mbps 100 Mbps None GE-PON (Gigabit Ethernet PON) IEEE 802.3ah 1 Gbps (std) 2.5 Gbps (dual speed) 1 Gbps (std) 1 Gbps (dual speed) None 10GE-PON (10 Gigabit Ethernet PON) IEEE 802.3av 10 Gbps 1 Gbps RF Overlay using 1550nm optical λ DOCSIS over EPON (DePON) – a combination of EPON & DOCSIS leveraging a cable operator’s DOCSIS network & OSSs (operational support systems). A DePON OLT looks & acts like a CMTS (cable modem termination system). SCTE 125 Mbps (32 passive optical split) 125 Mbps (32 passive optical split) RF Overlay using 1550nm optical λ DOCSIS 3.0 supports IPTV (internet protocol television) RFoG (RF over Glass); associated with specific FTTP products & an emerging standard; RF is transmitted over fiber, instead of coaxial cable, through splitters to a node or R-ONT @ the premises; requires the addition of an EDFA (erbium doped fiber amplifier) & return receiver in the hub or headend (HE) to support bi-directional optical transport on a FTTH P2MP plant. Use of existing HE/hub CMTS, eQAM, &/or CMAP along with CPE is required. SCTE 174 2010 160 Mbps (4-channel bonding) 160 Mbps bonding) DS RF Overlay using 1550nm & US RF Overlay using 1310nm or 1610nm optical λ DOCSIS 3.0 supports IPTV (internet protocol television) PON Categories as of 01 March 2011 GPS Global Positioning System; a constellation of geo-synchronous satellites that provide navigation and time information. Grade A Contour The area in which the quality of television broadcast reception is satisfactory at least 70% of the time for at least 90% of the receiving locations. Grade B Contour
Leapfrogging Cable television operators' practice of skipping over one or more of the nearest TV stations to bring in a further signal for more program diversity. FCC rules establish priority for carrying stations that lie outside the cable systems service area. Leaseback The practice by telephone companies of installing and maintaining cable television distribution systems, and leasing the facilities back to separate contractors for operation of the system. Leased Access On some systems, a public access channel for which programmers pay a fee for use and are permitted to sell commercial time in their programming. Also known as Leased Channel. Least Significant Bit In a binary code, the bit or bit position assigned to the smallest quantity or increment that can be represented by the code. Leakage The undesirable passage of signal over the surface of or through an insulator. LEC Local Exchange Carrier; a local telephone company, i.e., a communications common carrier that provides ordinary local voice-grade telecommunications service under regulation within a specified service area. LED Light emitting diode. LEDs are used in various applications ranging from being used as simple display indicators to use in fiber optics as a relatively low cost light source. Level A measure of the difference between a quantity or value and an established reference. Level Diagram A graphic diagram indicating the signal level at any point in the system. LEX Local Exchange; synonym for central office (CO). LGID
One billionth of a second. NANP North American Number Plan Narrowband This medium is capable of carrying voice, fax, paging, and relatively slow-speed data (not full video applications), typically at 64Kbps or less. Narrowcasting Delivery of programming that addresses a specific need or highly focused audience. NASA National Aeronautics and Space Administration; The U.S. agency which administers the American space program, including the deployment of commercial and military satellites via a fleet of space shuttle vehicles. NASDA National Space Development Agency of Japan. NAT Network Address Translation National Cable Telecommunications Association (NCTA) The trade association for the cable telecommunications industry in the US. Or a voluntary association of cable television operators which, among other things, provides guidance on measurements and objectives for cable television systems in the USA. National Electric Code® (NEC) A standard governing the use of electrical wire, cable and fixtures installed in buildings; developed by the American National Standards Institute (ANSI), sponsored by the National Fire Protection Association (NFPA), identified by the description ANSI/NFPA 70-1990. National ISDN-1 The North American standard specification for ISDN service. National Television Systems Committee (NTSC) Committee that defined the analog color television, broadcast standard used today in North America. The standard TV format for North American television transmission is named after this standards committee; the format is 525 lines in a 4-MHz video bandwidth. All TV sets sold in North America are compatible.
DOCSIS leveraging a cable operator’s DOCSIS network & OSSs (operational support systems). A DePON OLT looks & acts like a CMTS (cable modem termination system). split) optical λ DOCSIS 3.0 supports IPTV (internet protocol television) RFoG (RF over Glass); associated with specific FTTP products & an emerging standard; RF is transmitted over fiber, instead of coaxial cable, through splitters to a node or R-ONT @ the premises; requires the addition of an EDFA (erbium doped fiber amplifier) & return receiver in the hub or headend (HE) to support bi-directional optical transport on a FTTH P2MP plant. Use of existing HE/hub CMTS, eQAM, &/or CMAP along with CPE is required. SCTE 174 2010 160 Mbps (4-channel bonding) 160 Mbps bonding) DS RF Overlay using 1550nm & US RF Overlay using 1310nm or 1610nm optical λ DOCSIS 3.0 supports IPTV (internet protocol television) PON Categories as of 01 March 2011 RFoG Reference Architecture, excerpt from SCTE 174 2010 RF Overlay In an RF overlay, carriers send traditional cable video to the home as its own separate wavelength within the fiber — a 1550 nanometer stream that rides alongside the 1490 nm wavelength, carrying everything else (the high-speed Internet, the voice and the or VoD, content) as well as the 1310 nm wavelength going back the other way. RFP Request for Proposal RF Pattern A term sometimes applied to describe a fine herringbone pattern in a picture. May also cause a slight horizontal displacement of scanning lines resulting in a rough or ragged vertical edge of the picture. Caused by high-frequency interference. RG6 Cable
assignment. A cable modem may have one or more unicast SIDs. A group of cable modems may share a multicast SID. Service Information (SI) That information that describes the broadcast services available on the network. Service Profile Identifier (SPID) A number that the telephone company switching equipment uses to keep track of configuration information for each terminal adapter connected to an ISDN telephone line. The telephone company should give you your SPIDs at the time they assign you your ISDN directory numbers. Servo-loop Automatic device for regulating. Session Description Protocol (SDP) A DDE-1 protocol that defines a multicast session that may or may not be concurrent with a TV program. Or IETF protocol that describes multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. Session Initiation Protocol (SIP) An Internet protocol used for negotiating multimedia sessions across the network. Session Key A cryptographic key intended to encrypt data for a limited period of time, typically between a pair of entities. Set-Top Box (STB) Any of several different electronic devices that may be used in a customer's home to enable services to be on that customer's TV. If the “set-top” device is used only for extending the channels available, it is called a converter. If it restores scrambled or otherwise protected signals, it is a descrambler. SETI Search for Extraterrestrial Intelligence. SF Service Flow SFID Service Flow Identifier