bluuebunny/crossref_metadata_2025_split huggingface dataset:
Switching
Authors: Freeman Roger L. 
Published: November 2003

Abstract

This chapter deals with the switching function of the PSTN. It is the general policy of telephone companies/administrations and the ITU not to dictate switch design to manufacturers. The ITU and Bellcore (now Telcordia) are, however, concerned with the digital network and its performance. A switch is an integral part of this network. For example, a switch provides master clock to outgoing trunks connected to it. A switch can degrade error performance. It adds to the total jitter and wander accumulation across the network. Queueing and processing delays can add to total end‐to‐end delay. Careful switch design can keep these impairments within reasonable bounds. Many of these
reasonable bounds
are established in the ITU
Q.500
recommendations and by Bellcore.

Switch interfacing is very important to the network designer. A local serving switch usually encounters analog subscriber loops (lines) on one side and digital trunks (junctions) on the other. Concentrators may or may not be used on the line side. This switch compresses and expands. In other words there will be more lines than trunks, with a ratio as high as 12 to 1 or as low as 1.5 to 1 depending on whether the traffic sources are predominantly residential or commercial/industrial. A switch will be designed for a grade‐of‐service 0.01, often to 0.005 or better. We would expect to encounter CCITT Signaling System No. 7 on the trunk side, and one of several types of subscriber loop signaling on the line side. The line side may utilize a DSL (digital subscriber line) which would appear as a multiplex configuration, often related to DS1 or E1. If a switch interfaces with ISDN basic rate, digital subscriber signaling will probably be used. There is a North American version and a CCITT version.
Tandem and transit exchanges do not provide compression and expansion. The number of trunk inlets will equal the number of trunk outlets. Tandem switches may provide a CAMA (centralized automatic message accounting) function. Modern tandem/transit exchanges use CCITT Signaling System No. 7.
Digital switch design is almost universally such that with small changes in peripheral equipment, the switch will serve either in an E1 or DS1 environment. The switch will consist of a switching fabric, peripheral equipment, and a processor/computer based control function. The switching fabric will often consist of time and space switching stages.
Numbering, Routing, and Networks
Authors: Freeman Roger L. 
Published: November 2003

Abstract
Nearly every telephone subscriber in the world can access every other subscriber. Such calls are routed over a vast international network based on direct/high‐usage routing and, in some cases, third country transit exchanges, connecting one or more international switching centers (ISCs) in each country. Each nation has its own national network that is a functional part of the international network. This chapter provides design data and standards material on those networks.
A telephone call is routed to its destination over the network [variably called the PSTN or public switched telecommunications (telephone) network] based on the telephone number provided by the calling subscriber. Thus, the first section of the chapter deals with numbering, the ITU‐T world numbering plan, and the North American plan. There is a brief section on international routing. This is followed by a section on the North American network and routing. Digital network management and quality of service (QoS) are briefly discussed.
Noise, Modulation, and Other Radio System Parameters
Authors: Freeman Roger L. 
Published: November 2003

Abstract
This chapter provides essential background material, basic data, and review of some key radio transmission parameters. Electrical noise is the key impairment in any transmission system. The chapter covers a basic treatise on thermal noise and includes discussions on intermodulation (IM) noise, frequency modulation (FM) noise, and phase noise. There is a short review of angle modulation, and a guide to the selection of digital modulation techniques for radio transmission is given emphasizing spectrum conservation. This is followed by a short discussion of four advanced digital modulation techniques such as block‐coded modulation, partial response with soft decision demodulator and trellis‐coded modulation. Information on the necessary bandwidth required for certain modulation techniques is covered; also discussed are ITU‐R (CCIR) views on radio frequency (RF), peak envelope, average and carrier power, and intermodulation products.
Multiplexing Techniques
Authors: Freeman Roger L. 
Published: November 2003

Abstract

Multiplexing facilitates the transmission of two or more information channels on a single transmission facility such as a wire pair, fiber‐optic strand, or radio carrier. Multiplexing can be either in the frequency domain or in the time domain. When in the frequency domain, it is called
frequency division multiplex
(FDM). When in the time domain, it is called
time division multiplex
(TDM).

FDM was the multiplexing technique of choice from before WWII to about 1985, when TDM systems became prevalent. At this juncture, nearly all multiplexing systems being implemented in the public switched telecommunication network (PSTN) use TDM.

For PSTN applications, the most prevalent type of TDM is called
pulse code modulation
(PCM).

As PCM systems evolved, two different underlying standards were developed. These may be typified by a North American standard popularly called T1 and by a European standard previously called CEPT30 + 2 and now popularly called E1. [CEPT stands for Conference European Post (and) Telegraph, a French‐dominated standards agency, now called ETSI (European Telecommunication Standardization Institute).] Both types of PCM standards are covered in chapter.
Because of the overwhelming dominance of PCM in the world's various networks, great emphasis has been placed on this multiplexing technique.
The Digital Network
Authors: Freeman Roger L. 
Published: November 2003

Abstract
The objective of this chapter is provide realizable performance objectives of the digital network as well as the impairments that can be expected and how to limit their impact on those performance objectives. The chapter also covers network synchronization without which that network would become inoperable or very badly degraded with excessive slips.

The
digital network
to which we refer is the underlying network supporting the PSTN. In industrialized countries the PSTN is completely digital; in emerging nations it is rapidly becoming so. The PSTN is a network open to public correspondence which supports the communication of voice, data, and video. There are also private and industrial networks. In many situations these private networks are backed up by the PSTN in case of dramatic failure or catastrophe. It is just for this reason we recommend private and industrial networks to follow PSTN practice (in most respects) so that there is a viable interface when the need arises. It is assumed that the digital network is based on 8‐bit PCM using either A‐law or μ‐law companding discussed earlier.

In North America there is not one singular network, but many networks under different ownerships. With the divestiture of the Bell System, seven regional Bell operating companies came into being. The long‐distance network consists of several or many competing carriers or IXCs depending on how one wishes to define a long‐distance carrier. Those with their own facilities with thousands of miles of transmission facilities and multiple switches may amount to six or seven, while others just resell service. The fact there are many interconnecting digital networks poses some difficult interfacing issues for the network designer, particularly multiple clock problems, where each of these networks has its own master clock.
Line‐of‐Sight Microwave
Authors: Freeman Roger L. 
Published: November 2003

Abstract
This chapter encompasses many of the basic design data elements for the planning, analysis, and implementation of line‐of‐sight microwave/millimeter wave radio‐links emphasizing point‐to‐point service.
Since 1975, the trend has been to implement digital line‐of‐sight (LOS) microwave because the world's networks either have become all‐digital or are rapidly becoming all digital. Because of the scarcity of available usable spectra, a particular burden has been placed on the microwave design engineer to conserve spectrum. Assuming a bit rate bandwidth, a digital voice channel occupies 64 kHz, whereas its analog counterpart would only use 4 kHz operating in a single sideband (SSB) mode. Thus, the system designer must turn to available bit packing techniques usually involving some sort of quadrature amplitude modulation (QAM) waveform. The 512‐QAM equipment is available with 1024‐QAM systems on the drawing boards providing 8 and 9 bits per hertz, respectively, of bit packing.
Line‐of‐sight microwave technology has two direct outgrowths: troposcatter/diffraction radiolinks and satellite communication systems. In fact, a communication satellite transponder is no more than a radiolink repeater or a regenerative repeater with possibly some additional signal processing. Another allied technology, mobile radio, covered under various terms such as cellular radio, personal communication services, or “wireless” communication, is also an extension of LOS microwave.
Meteor Burst Systems
Authors: Freeman Roger L. 
Published: November 2003

Abstract

Meteor burst communication (MBC) is a comparatively low‐cost, low‐throughput data communication system. A single MBC link can have a range up to about 1000 km. Data may only be passed when there is a common meteor trail visible by both the transmit and receive antennas. Such a trail may provide a viable path for periods up to 1 or 2 s.
The period between viable trails is called waiting time
. MBC links are commonly used for monitoring of remote sensors, where each sensor may be polled several times a day. MBC systems operate in the region around 50 MHz, which is a compromise between meteor trail activity and intensity versus man‐made noise.
Forward Error Correction
Authors: Freeman Roger L. 
Published: November 2003

AbstractThis chapter presents both tutorial information and practical design data on the application of forward error correction (FEC) techniques. FEC may only be used with digital circuits.Forward error correction can be used to improve bit error performance on a marginal circuit or to lowerEb/N0requirements without impacting error performance on other digital circuits. The armed forces of the world were probably the first to put FEC to work. It now has universal acceptance in the commercial world. Where good bit error performance is crucial, one can expect to find FEC applied. This is particularly true on digital compression schemes such as motion picture experts group (MPEG). It is finding growing acceptance in the cellular/personal communication services (PCS) world and on line‐of‐sight (LOS) microwave and high‐frequency (HF) radio circuits.Coding gainis defined as the difference between requiredEb/N0for an objective target bit error rate (BER) between a certain coded system and the same system without coding. A radio system “gain” is traditionally achieved by increasing transmitter power, improving receiver sensitivity, applying diversity, and increasing antenna aperture. Now on digital systems, coding gain derived from FEC is still another method to achieve gain, usually at a fairly reasonable price, by the addition of a personal computer (PC) board at each end of a link. Coding gains of 2–5 (or more) dB are common. To improve coding gain still further,tandem codingcan be employed. This is also called concatenated coding, where there is an inner code and an outer code. On one application, the outer code was a convolutional code with a coding gain of 5 dB, and the inner code was a Reed–Solomon block code with a coding gain of 2 dB. The net coding gain in this case was 7 dB.Conventional wisdom agrees that the redundancy added for FEC requires an appropriate bandwidth expansion. When trellis‐coded modulation (TCM) is used, this is not the case. TCM is particularly attractive on digital LOS microwave circuits, where conservation of bandwidth is so important.
Facsimile Transmission
Authors: Freeman Roger L. 
Published: November 2003

Abstract
Facsimile (fax) is a method of electrical communication of graphic information. It is used to transmit pictorial or printed matter from one location to another with reasonably faithful copy recorded at the receiving end. Fax has been designed primarily to operate over comparatively narrow‐band media, lending itself to transmission over the telephone network on the standard 4‐kHz voice channel and on HF radio. Facsimile is transmitted in either (a) black and white or (b) black and white with various shades of gray. One system in operation has 256 shades of gray. Fax has truly become ubiquitous in many parts of the world.
This chapter is primarily concerned with facsimile interface data and standards, derived primarily from ITU‐T (CCITT) and US military documents. Another source is the US Electronic Industries Association (EIA). However, much of the EIA material is similar to ITU‐T Recommendations, and for that reason it has not been included.
Adaptive Systems, Rotary Wing Applications
Authors: Chattopadhyay Aditi , Rajadas John 
Published: November 2003

AbstractAn intelligent or smart structure is generally considered an integrated system of structure, sensors, actuators, and a control module. Currently, there is a great deal of interest in applying smart structure technology to various physical systems. Active vibration, noise, aeroelastic stability, damping, shape control, health monitoring, process monitoring, and damage and delamination detection are a few examples. A significant amount of the early development was devoted to application to space‐related systems. Recently, studies have also been conducted to investigate using this concept to improve fixed wing performance. During the last decade, significant research efforts have also been directed toward applying these concepts to rotary wing aircraft which is the topic of this article. The potential for improving performance, handling qualities in stall, and increasing fatigue life is discussed. Actuators that use smart materials require relatively slow‐acting shape and shape‐distribution changes in this respect. A similar review is made of applications for improving aeroelastic divergence, flutter instabilities, and tail buffeting on fixed‐wing aircraft and reducing vibrations, improving external acoustics, and providing flight controls for rotary wing aircraft—all of these require a high‐frequency response.Vibration and noise are two long‐standing problems that have limited the expansion of military and commercial applications of rotorcraft. Helicopters are particularly susceptible to high vibratory loads compared to fixed wing aircraft due to the high unsteady load and complex aerodynamic environment in which the rotor must operate and the existence of the complex structural, aerodynamic, and dynamic coupling.A major improvement in helicopter performance can be achieved by implementing active rotor control technology. Smart material actuator technology for operation “on the blade” is now becoming available and promises to overcome the size, weight, and complexity of hydraulic and electric on‐rotor actuation which should alleviate the problem. Blade actuation by smart materials offers the chance for an electrical system integrated into the blade itself. Unfortunately, the development of high force/high deflection actuators, the most critical issue in all of these applications, has not been addressed adequately and still remains a topic of future research. In all applications involving smart materials, accurate modeling of the material response and the integrated smart structural response is important because control authority can be significantly mispredicted if inaccurate theories are used. In this article, the current state of the art in improving rotor vibratory response and aeromechanical characteristics is reviewed. Advantages and disadvantages of these techniques are discussed. Numerical results from feasibility studies are summarized, and accomplishments already achieved and the goals to be pursued in the near future are discussed.
Biomedical Applications
Authors: Qiu Jinhao , Tanaka Mami 
Published: November 2003

Abstract
Biomedical applications of smart materials can be divided into three categories: (1) implants and stents, such as bone plates and marrow needles; (2) surgical and dental instruments, devices, and fixtures, such as orthodontic fixtures and biopsy forceps; and (3) devices and instruments for medical checkups, such as ultrasonic devices. The applications of the first category require strict biocompatibility of a material because it is implanted in the body for long periods. Among many traditional materials, including metals, alloys, and ceramics, that are available commercially, only a limited number are currently used as prostheses or biomaterials in medicine and dentistry. The applications in the second category require excellent mechanical characteristics as well as biocompatibility. The third category is used mainly for transducers.
Among smart materials, the Ti–Ni shape‐memory alloy (SMA) has attracted the most attention for biomedical applications in the first and second categories due to its excellent biocompatibility and mechanical characteristics. Research on biomedical applications of the SMA started in the 1970s with animal experiments initially, followed by clinical tests. The first example of a successful biomedical application of the SMA was a bone plate, which was used to repair broken bones. Now, many medical and dental applications of SMAs are available, and many new applications are being developed. On the other hand, piezoelectric materials have been widely used as transducers for medical ultrasonic devices due to their sensor function that uses piezoelectricity and the actuator function that uses inverse piezoelectricity.
In this article, the properties of SMAs for biomedical applications are discussed next, followed by some clinical examples. Recent examples of biomedical applications of SMAs are summarized there after, and finally the recent examples of biomedical applications of piezoelectric materials are summarized.
Biomedical Sensing
Authors: Brazel Christopher S. 
Published: November 2003

AbstractIn recent years, biomedical diagnostics research has led to the development of simple, less invasive, and more accurate evaluative techniques. Much of this is due to biosensor technology, which has played an important role in material improvements used to sense, carry signals, and respond to signals. Biosensor devices can measure micromolar or even smaller quantities of biological substances, including chlorides, glucose, lactose, and urea. Medical applications abound, ranging from diagnostic tests for home testing toin vivomonitoring of vital conditions and using feedback to control drug delivery or send amplified signals of a change in patient health. Smart materials are frequently combined with biological components to create systems that respond to environmental conditions, such as temperature, pH, concentration of particular analytes, or even light. These smart materials are typically polymeric, and most have the common characteristic that changing environmental condition cause a thermodynamic change between hydrophilic and hydrophobic states, as detailed later. pH paper strips may be one of the simplest sensing devices; they relay a physiological condition through a colorimetric response, and because they are a form of dry chemistry, they simplify detection and diagnostics, which is especially important for home diagnostic kits.This article presents the use of intelligent polymers in sensing systems, that range from traditional biosensors to advanced self‐responsive systems. This review of biomedical diagnostics using smart polymers examines some of the medical applications for intelligent polymers used in electrode‐based systems and in bioconjugate systems. Sensing devices are categorized by the mechanisms of signal detection and response, and examples of systems that monitor analytes, such as glucose, are addressed. Additional modes of response beyond the traditional electronic signal as well as synthesis techniques and examples of medical diagnostics using smart polymers, will be discussed.
Biosensors, Porous Silicon
Authors: Janshoff Andreas , Steinem Claudia 
Published: November 2003

AbstractBiosensors consist of a biologically active layer that responding to an analyte in solution and a powerful transducer that transforms and amplifies the reaction into a measurable signal. Biosensors can constantly measure the presence, absence, or concentration of specific organic or inorganic substances in short response time and ultimately at low cost. They are used commercially in health care, biotechnological process control, agriculture, veterinary medicine, defense, and environmental pollution monitoring. A common requirement of all of these applications is on‐site chemical information—preferably in real time—on some dynamic or rapidly evolving process. Most biosensors are based on molecular events as they take place at the cellular membrane or inside the cell involving enzyme cascades. Their perceived advantages over existing technologies include the ability to monitor broad or narrow spectra of analytes continuously in real time, and their weakness is the instability of the biological molecules outside their natural environment, which results in a restricted lifetime for the device. The challenge is to find a matrix for biomolecules that provides high compatibility of the material with biological substances, low‐cost fabrication, and special optical and electrical properties to generate a signal that measures the interaction between analytes in solution and the receptive biological layer. It is also desirable that it be compatible with conventional microfabrication techniques to miniaturize the device or to build individually addressable arrays.The high surface area in conjunction with its unique optical and electrical properties and its compatibility with silicon microelectronics fabrication techniques has led to the proposal that porous silicon may be a suitable material for building sensor devices. Several different transducer schemes have evolved based on thin film interference, capacitance changes, and the photoluminescent properties of porous silicon and these are discussed.