Fiber Optics Illustrated Dictionary - Part 80 ppsx

Fiber Optics Illustrated Dictionary late 1980s and the 1990s and, more recently, has in- troduced Super DLTtape technologies that provide fast transfer-rate, high-capacity storage on tape car- tridges. See Super DLTtape. Quantum Flow Control QFC. In ATM networks, a congestion avoidance scheme proposed for use on available bit rate (ABR) connections. For example, in a network in which VCI tunneling is implemented, the ATM device will send only after receiving explicit credit from a receiving ATM device at the other end of the connection. If tunneling is not used, buffer al- location and a credit manager must be included. If the buffer allocation is exceeded, noncomplying cells will be discarded. quantum mechanics The study of atomic structure and behaviors using various measuring instruments and techniques. See Heisenberg uncertainty principle, quantum. quantum noise When using a detector to investigate quantum characteristics in electromagnetic phenom- ena, there may be noise from random variations or fluctuations in the average rate of incidence of quan- tum interactions with the detector. These may be ex- pressed in terms of photons. quantum well QW. A quantum phenomenon associ- ated with a structure fabricated from ultrathin alter- nating layers of wide bandgap (barrier) and narrow bandgap (well) materials. When an electron is caught in a well formed between the barriers, the probabil- ity of escaping the well is limited and the electron's energy level is affected. The quantization effects re- sulting from these events are related to the height and width of the fabricated barrier and can be derived through quantum mechanical calculations. Quantum well exhibiting structures can be constructed using crystal growth techniques (for use in quantum cas- cade lasers, for example). Quantum well components have unique properties that can be exploited for a variety of optical communications technologies. Quantum well physics can be used to create modula- tors through the application of an electrical field per- pendicular to the surface of the quantum well or al- ternately to its sides. Thus, the optical absorption of the QW is changed sufficiently to make it useful for signaling. This phenomenon can be exploited for semiconductor design to make small optical modu- lators with two-dimensional optical arrays. A quantum well infrared photodetector (QWIP) is a multiple quantum well device based upon layered high-bandgap semiconductor fabrication. Bandgap discontinuity associated with the layers of differing materials creates quantized sub bands in the potential wells. The phenomena associated with the layers is a photoexcitation of electrons between ground and first excited-state subbands. The carriers resulting from the photoexcitation are then able to escape from the potential quantum wells to generate a photo current. In the U.S. Naval Research Lab, quantum well phys- ics has been used to develop a number of types of semiconductor lasers emitting mid-infrared light. Using "wavefunction engineering," engineers have designed complex, layered quantum well structures. 782 This has a number of possible applications, includ- ing laser radar (ladar). Researchers at Imperial College demonstrated a new quantum well solar cell (QWSC) that may be more efficient than previous solar energy sources. In 1997, scientists described an uncooled strained quantum well laser that could be used in SONET/ SDH networks, especially short- and medium-haul transmissions. See electroabsorption, quantum cascade laser, self- electro-optic effect device. Quarter Common Intermediate Format QCIF, Quarter CIF. A standard for the transmission of video frames in the lTU-T H.261 standard. QCIF consists of 144 lines of luminance and 176 pixels per line (144 x 176 CIF format is optionally supported by H.261). This relatively low resolution creates an im- age that has a soft-focus, indefinite appearance, but has the advantage of using fewer system resources and less bandwidth. In fact, the standard was devel- oped with the needs ofcircuit-switched networks in mind. For small windows, simple images, and small display devices, it has practical applications, and it is widely favored for videoconferencing, especially on ISDN networks. H.261 is usually implemented in conjunction with other related standards. See Com- mon Intermediate Format. QuarterInch CartridgeDrive Standards QIC. An international association, established in 1987, to pro- mote the acceptance and use of quarter-inch readable/ writable data cartridge drives and media. These types of storage media are commonly used for computer backup, secondary storage, and temporary storage for files that need to be transported. More than 100 QIC standards have been developed since 1988. QIC-40, QIC-80, QIC-3101, and QIC- 3020 have been particularly prevalent in the tape car- tridge field, although they are now being superseded by higher capacity formats. A complete list and fuller description of each standard are available on the QIC Web site. http://www2.qic.org/ quarter wave The distance, or elapsed time, in a con- ducting line or through a conducting space, which is 90° to a wave disturbance. This information in used in the design of antennas and in the quadrature trans- mission of signals, particularly in modulation schemes. See quadrature. quartz A silicon dioxide mineral found or synthe- sized in crystal fonn and in crystalline masses, which is widely used in scientific research and telecommu- nications due to its oscillating qualities. Quartz is transparent, harder than glass, and varies in its oscil- lating frequencies depending upon its size and shape. Quartz crystal watches are extremely accurate, and quartz arc lamps are used for sterilization, due to the way ultraviolet light passes through the crystal. See piezoelectricity. QuartzA2D graphics engine from Apple Computer, based upon the standardized Portable Document F or- mat (PDF). Quartz is incorporated into Mac OS X. quartz (symb. - Si0 2 ) A mineral silicate of the sili- con dioxide quartz group with a unique helical © 2003 by CRC Press LLC structure and piezelelectric properties that have many applications in electronics. quartz crystal component A piece of quartz cut to a precise size for a specific purpose. Quartz has re- markable constancy in its vibratory qualities, mak- ing it suitable for extremely precise time devices. These vibratory qualities can be controlled by ma- nipulating the shape and size of the crystal. Early ra- dio sets were called "crystal detectors" as they used crystals (galena and carborundum were popular) to detect (rectify) and channel a radio wave. Quartz is commonly used in oscillators and filters. Quartz crys- tals are used to provide timing in watches and to stabi- lize broadcast waves. See quartz, quartz crystal filter. quartz crystal filter The properties of quartz crys- tals make them useful for a variety of applications that require highly selective electrical circuitry, and hence they are used in the creation of various types of filters. Synthetic quartz crystals, developed in the 1950s, furthered the manufacture of quartz filters for use as electronic components. There were, in fact, few other materials that offered the advantages of natural or synthetic quartz until the development of lithium-tantalate crystals in the Bell Laboratories. See lithium-tantalate, quartz, quartz crystal. quartz tuning fork QTF. A specialized instrument exploiting the piezoelectrical properties of quartz. In 1995, it was suggested by Karrai and Grober that QTFs could be used for measuring shear forces on scanning near-field optical microscope (SNOM) fi- ber tips. Subsequent research has led to the develop- ment of QTF mechanisms for non-optical distance stabilization in atomic force microscopes (AFMs) for the realization of apertureless SNOM. See scanning near- field optical microscope. quaternary phase-shift keying QPSK. A modula- tion technique which is used to encode digital infor- mation to be transmitted over wire or fiber networks. It is a subset of phase shift keying (PSK), and is es- sentially a four-level version of phase modulation (PM). QPSK divides the bit stream into two streams, and sends them alternately to in-phase and out-of- phase modulators, where they are subsequently de- modulated at the receiving end. QUBE An Interactive TV information utility. Warner instituted the QUBE interactive educational TV net- work in the late 1970s. The first interactive televi- sion concert, broadcast live over the QUBE system in 1978, featured Todd Rundgren, pioneer multime- dia recording artist. quench To bring to a sudden halt, to cool rapidly, to quickly extinguish a flame, spark, or gas emission. quench oscillatorIn some super-regenerator circuits, a type of ultrasonic oscillator which serves to quench, or rapidly reduce, the regeneration when it has almost increased to the point of oscillation. quenched sparkgap Early wireless transmitters used spark gaps in their spark transmitters, with several types of gaps: open gaps, rotary gaps, and quenched gaps, each with different strengths and weaknesses. Quenched gaps employed a racklike series of metal plates separated by thin layers of mica, resulting in a very small spark that is quickly quenched and does not tend to overheat as do open gaps. Due to improve- ments in technology and the need for regular clean- ing to keep quenched gap transmitters working opti- mally, they were eventually superseded by continu- ous wave (CW) transmitters. query 1. Request for data, in which the content of the data is the desired result. Common in database applications. 2. Request for data which provides in- formation about the state (operating parameters, mode, security, etc.) or functioning (availability, readiness, status, responsiveness, etc.) ofa system. Usually at a low operating level and generally trans- parent to the user. query by example QBE. An idea introduced in the 1970s whereby a user interacts with a front end to a database by supplying examples of the type of infor- mation that the user wants to retrieve. Sometimes this is more practical than querying by keywords or al- gorithms. A number of popular database programs provide this capability. query language A programming language intended to facilitate search and retrieval of information, usu- ally from a database. Query languages are frequently in the form of interpreted scripting languages or graphical report generators, with commands that are similar to common English words, to make them easier to program by those without programming backgrounds. Query on Release QoR. A telephone number port- ability mechanism suggested by Pacific Bell to trig- ger a database query, depending upon circumstances related to a subscriber's current carrier. In QoR, a tele- phone call setup signal is routed to the end office switch to which the dialed phone number was origi- nally assigned (e.g., the NPA-NXX of the dialed num- ber). If the dialed number has been transferred to an- other carrier's switch, the database is queried for rout- ing information and the call completed to the new switch. The system is also called Look Ahead. In 1997, the Federal Communications Commission affirmed its conclusion that this (interim) solution was not acceptable over the long term because it violated a statutory requirement for consumers to retain num- bers without impairment of the quality, reliability, or convenience when switching carriers. The Commis- sion felt that degradation in service in terms of post- dial delays could compromise QoR forwarding and supported Location Routing Number (LRN) as statu- torily acceptable. See Release to Pivot. queue A stream of items or tasks waiting to be pro- cessed or executed, such as calls to an operating sys- tem, a network, or a phone system. Queues are used to maximize the use of existing resources, especially on shared systems. It's expensive to put a printer on every computer in a network and, since printing doesn't happen as often as data input/output, it's not efficient either. By allocating one printer to every few workstations, user print requests can be handled ef- ficiently by the network, with simultaneous requests administered through a set of parameters. This also can improve resource choice. By sharing printers, it 783 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary may be possible to offer avariety of types ofprinters and paper sizes, which is more practical and economi- cal than trying to purchase several printers for each computer. See queuing. queue administration Queues are widely used to manage resource-sharing on a network. Whether the resource is a printer or modem, applications program, data file, or gateway to the Internet or Web, computer systems create, manage, authorize, and prioritize ac- cess to these resources and services through queues which are usually transparent to the user. On phone networks, queue administration may in- volve putting a caller on hold, checking to see if and when agents are ready to take the call, playing peri- odic messages to the caller, and assigning the call to the appropriate agent. On computer networks, queue administration may involve logging in users as they sign on to the sys- tem, checking for the existence of devices when a resource request occurs (e.g., a printing job), deter- mining if others are in the queue, and where to slot the new request (the size of the print job, or relative priority of the user requesting the job may be taken into consideration), and may even change the queu- ing arrangement dynamically if another printer comes online or a print request is canceled before the job is run. Queued Telecommunications Access Method QTAM. An IBM communications control protocol which handles some applications processing tasks. QTAM is used in a number of telecommunications applications, including message switching, data pro- cessing, etc. queuing delay QD. In its most general sense, a de- lay caused by queues or lineups within a system through which objects, information, or data are chan- neled. As a simple example, shopping in a downtown store with a queue at the cash register can result in a delay that causes a shopper to receive a parking ticket. When placing a phone call, a delay may be imposed on the caller by congested trunk lines or by the vari- ous switchers, routings, and routing priorities inher- ent in or configured into a system. Queuing delays can have many negative effects including customer frustration, loss ofrevenue, extra costs, and even death (in the case of emergency calls), so queuing theories and solutions are considered to be an impor- tant aspect of telecommunications. The queuing delay in a transmission system can be assessed in terms ofparticular legs within a route or in terms ofatransmission as a whole, from sender to recipient. This is often a dynamic process without a single catch-all solution. Queuing delay is often evaluated in conjunction with other types of delays, including processing, propagation, and transmission delays. Queuing refers to those aspects where data or objects "bump up" against one another, in the sense that (usually) similar objects congregate "behind" one another in order to pass through a gateway or other channel that cannot accommodate the queued enti- ties simultaneously. In cell-based transmissions, a queuing delay is a de- lay imposed on a cell due to the current inability of 784 the cell to be passed on to the next element or func- tion (because of congestion or errors). Depending upon the system and priorities, significant delays may have several results; the buffered cell data may be re- turned or destroyed. See queuing theory. queuing theory Queuing, in its broadest sense, in- volves an understanding ofmathematics, statistics, modeling, data flow, and human behavior as they re- late to the ways in which machines may be config- ured, tuned, and operated so as to carry out worth- while tasks and processes in an efficient and orderly manner. Researchers in queuing theory regularly come from fields such as probability mathematics, complex systems theory, and simulation research. In the context of networking, queuing theory focuses on understanding, describing, and predicting patterns in transmission organization, priorities, delay, loss, and standards for quality ofservice (QoS). One of the most important pioneers of queuing con- cepts was Danish telephone engineer A.K. Erlang, who studied and described telephone traffic in its mathematical context and practical applications in the early 1900s. Another significant contributor to the body of knowledge in queuing theory is Leonard Kleinrock, who was involved in the early develop- ment of the ARPANET and who authored Informa- tion Flow in Large Communication Nets, in 1961. He subsequently wrote Communication Nets, in 1964, which provides design and queuing theory for build- ing packet networks, in spite ofa common sentiment at the time that packet switching wouldn't work. Queuing theory is an important aspect of performance evaluation and configuration in communications net- works. Without a theoretical model for installing, configuring, and tuning a network, much time can be wasted in trying out the many different ways in which network traffic can be routed, especially in aheavily used system in which congestion and "bursty" traf- fic occur. Queuing applies to a broad range ofenvi- ronments, from individual circuit transmissions to global distributed networks. A single queue system is one of the most basic mod- els discussed in queuing theory. When all traffic is routed through a single channel on a first-come, first- served basis (e.g., a single cash register in a comer grocery store), the impact ofextra traffic and over- flow may be different from traffic management in multiple queue systems (a supermarket with multiple cash registers or multiple tumstyles at a sports sta- dium). The same concepts can be applied to telecom- munications systems. A single phone routed through a dedicated line will be managed differently from a single line through a public phone system (wireline or wireless) where congestion might occur. The prob- lems of queuing become more intricate when mul- tiple users ofmultiple phones (or modems) are shar- ing network resources over a public network, espe- cially in distributed networks where individual nodes mayor may not be available at any particular point in time. See Erlang, Agner; queuing delay. QUICC See Quad Integrated Communications Con- troller. © 2003 by CRC Press LLC quickconnection blockA connection block for more quickly and easily making electrical connections without the necessity of learning to use specialized tools and wiring codes. Quick connection blocks are typically made of plastic or other nonconductive materials with metal terminal connecting points and may be preterminated for ease of installation. They are sold for a variety of uses, including electrical wir- ing, quick installation of multiple lights, computer network connections, and internal telephone line in- stallation, especially for multiphone systems. Quick connection blocks are especially appealing to small businesses installing their own phone systems. These blocks enable wires to be inserted with easily available screwdrivers, pliers, and wire cutters rather than punchdown tools. One common configuration for telephone quick connection blocks is a premade 66 block, so-called because it supports up to 66 cross- connections. Panasonic has a commercial Quick Connect Block, a premade 66 block, that connects to the standard building wiring and supports up to eight analog or digital phone stations for each block (depending upon the phone model). Homaco, Inc. provides premade 66 blocks for tele- phone connections in 25-, 50-, and 100-pair sizes. Comm-Omni International supplies cable termination and surge protection for cables for multiple-family residences and office buildings (e.g., private branch exchange terminations) with a quick connection block accessory with 50 6-pin interconnected rows. QuickFileAccess QFA. A system for enabling faster access to data on tape-based storage systems such as computer cartridge drives. Prior to QFA and similar systems, tape drives had to read through blocks of data sequentially to find the desired data, resulting in slow read times, especially if the desired data were near the end of the tape. With tapes and data stored on tapes getting longer, this became impractical. Thus, a system of commands known as Quick File Access enables a block number to be read so that the tape can be fast-forwarded to the appropriate place in the tape to locate the data. Since the block infor- mation pointers cannot be easily manipulated on tape, they are usually held in a database. Unfortunately, if the database is compromised (or logging disabled), then data location can be a problem (especially if it is a backup tape to restore a crashed system upon which the database was stored). Nevertheless, QFA is much more convenient than traditional serial-ac- cess tapes. quick-break fuse A type of fuse which breaks a cir- cuit very quickly ifa surge or other anomalous elec- trical condition occurs. Quick-break fuses are espe- cially useful with electronics components, which are sensitive to electrical fluctuations and prone to damage. QuickDraw A widely used proprietary computer drawing and display specification from Apple Com- puter Inc. QuickDraw can display screen images and processing PostScript files so they can be printed on nonPostScript-equipped printers. quicksilver colloq. mercury. QuickTime Aproprietary cross-platform computer display, audio, and animation environment from Apple Computer Inc. that runs on Macintosh, Power- Mac, Windows 95, Windows NT 4.0, Windows ME, and Windows 2000. QuickTime is actually a suite of software applications for supporting picture display, multimedia authoring, and server support for stream- ing audio/video. QuickTime allows some interesting applications to be developed and distributed, including frame-based animation, whiteboarding, video clips, teleconferenc- ing applications, virtual reality environments, games, and more. The QuickTime fonnat is widely supported on the Internet, with many Web-based multimedia applications distributed in QuickTime. Many digital cameras also support the QuickTime format. Most recently, QuickTime has been enhanced to sup- port streaming media in Internet browsers (HTTP, RTP, RTSP) to support more than 30 different audio and video file formats (AIFF, BMP, GIF, JPEG, MPEG-l, MP3, M3U, PICT, PNG, SGI, Targa, TIFF, VR, Wave, and more), and added modules for sav- ing digital video (DV) camcorder formats for the de- velopment of digital video. Most QuickTime software is freely distributed, in- cluding the QuickTime Player and Picture Viewer. The QuickTime Streaming Server and Darwin Streaming Server are also freely distributed, with no streaming data license fees. See QuickTime chart. quiet tuning In radio receivers, a tuning character- istic in which the signal is kept quiet, that is, not broadcast to the listener, except when the tuner is ~~~: i~~~:?~~l~:J~~~~~~.a I~~~~~~~J:.e~cr; II isn't a good signal, the receiver mutes the sound to save the listener from the distraction of weak or noisy stations. Quorum International The marketing and distribu- tion arm of Applied Electronics, a Hong Kong-based Original Equipment Manufacturer (OEM). Applied Electronics supplies many major computer and com- munications companies, including National Semi Conductor, IBM, Texas Instruments, and others. Products include security systems and pagers. In con- junction with MCI, the MCI-Q Program was devel- oped to enable Quorum to purchase communications products and services at special rates. Through the Quorum Associate Distributor (QuAD), distributors receive discounted Mel Q-Connection rates and ac- cess to additional services (pagers, calling cards, etc.). Quorum Teleconferencing Bridge A commercial, integrated voice and data device from AT&T to fa- cilitate conference call set up and administration. The Quorum Teleconferencing Bridge connects and con- trols multipoint conference calls. It enables a local operator to set up, control, and monitor up to four si- multaneous conference calls from participants in up to seven locations for each call (or a single meeting with up to 28 locations). QWERTY A ubiquitous computer and typewriter keyboard configuration designation, named after the six lettered keys on the top left side. Although each 785 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary computer keyboard has different symbol and func- tion keys, most follow common QWERTY configu- rations. QWERTY was originally designed to slow down typing to prevent jamming on old manual type- writers (they jam easily). Other keyboard layouts have since been proposed which consider ergonomics and physical properties, the most recognized being the keyboard designed by August Dvorak. The Dvorak keyboard was developed on the basis of studying finger motion and lettering combinations which were easier and more efficient to execute, and incorporating them into new keyboard character arrangements. A number of variations of this by other people have also been called Dvorak keyboards, even when they differ from that developed by A. Dvorak. Unlike typewriters, it's easy to remap key positions on computer and alternate keyboards can be designed to put the letters anywhere the user desires. In spite of this, QWERTY keyboards remain prevalent, and manufacturers and teaching institutions are reluctant to change to other systems. Qwest Communications A telecommunications company establishing fiber optic networks in over 100 U.S. and Mexican cities. Commercial services provided include dedicated business Internet access, Internet faxing, Internet phone (Q.talk), and video. In June 2000, Qwest Communications International Inc. completed a merger with U.S. West, Inc. an- nouncing an $85 billion market capitalization with services in 14 states. In October 2001, Qwest and its principal shareholder, Anschutz Company, an- nounced plans to purchase 14 million and 6 million shares, respectively, of the Netherlands company Koninklijke KPN N.V. The company further an- nounced plans for acquiring Global TeleSystems, Inc., to embark on a significant European expansion. QZ billing Atelephone subscriber service in which the time and charges for an outgoing call (usually a toll call) can be obtained from the phone company. This is especially useful for business professionals and educational institutions that bill back to the call- ing department. QZ billing is being superseded by automated call accounting information. QuickTime Applications Application Description QuickTime 3D Apple Computer's 3D QuickTime cross-platform 3D rendering software. QuickTime Conference QTC. Designed on Apple Computer's QuickTime compression technology, QuickTime Conference supports videoconferencing in a window on the com- puter screen. Electronic whiteboarding is also supported, so participants can communicate and collaborate on shared drawing, text, or other projects. The software can be used to deliver Web events using QuickTime Live! software. See Simple Multicast Routing Protocol. QuickTime Player A software application for playing back audio and video files created by QuickTime Pro authoring software and other applications that export the QuickTime Pro authoring file format. QuickTime 5 has support for skip pro- tection for streaming sources with uneven video delivery, media "skins" to enable the user to customize the look of the player, Internet TV channel dis- play and audio control features, and support for plugins from Apple and third- party developers. QuickTime Pro Alow-cost, commercial authoring system for creating QuickTime multime- dia images and presentations. It SUpp0l1S many popular file formats that may be played on freely-downloadable QuickTime Player programs. QT Streaming Server An extension to QuickTime to deliver realtime multimedia over the Internet using the Real-Time Transport Protocol/Real-Time Streaming Protocol (RTP/ RTSP). Thus, it can deliver video-on-demand and, when combined with broadcasting software, live streaming news, interviews, or entertainment through a network. QuickTime Streaming Server is available in Mac as x Server and the Darwin Streaming Server is available through the Darwin open source project. The Streaming Server is available on a variety of platforms and the open source software makes it possible to port to additional platforms. The software provides Web-based server configuration, TCP-based broad- cast support, skip protection, and other features. QuickTime VR An extension to QuickTime that adds cross-platform virtual reality capabili- ties through amovie-like presentation of images. The user can move through the scene, pan the surroundings, interact with objects, and much more. Quick- Time Authoring Studio can be used to create virtual reality scenarios for dis- play in QuickTime YR. QTYR Make Cubic enables users to build Cubic Vir- tual Reality software. 786 © 2003 by CRC Press LLC r abbrev. roentgen (rentgen). See roentgen. R 1. symb. range. 2. symb. resistance. See resistance. R interface In ISDN, a number of reference points have been specified as R, S, T, U, and V interfaces. To establish ISDN services, the telephone company and ISDN subscriber typically have to install a num- ber of devices and links to create the all-digital cir- cuit connection necessary to send and receive digital voice and data transmissions. The R interface is the portion of the link between an ISDN terminal adapter (TA) on the customer pre- mises, and customer non-ISDN station equipment (TE-2) such as phones, facsimile machines, comput- ers using modems, etc. Some communications de- vices are being manufactured with ISDN terminal adapters built in, in which case, the R interface is not needed (or is considered to exist inside the compo- nent itself). See ISDN interfaces for a diagram. R reference point In ISDN, the point in the digital communications path at which non-ISDN TE-l de- vices connect to a Terminal Adapter (TA). See R in- terface. R Series Recommendations A series oflTU-T rec- ommended guidelines for radio systems, operations, and spectrum use. These guidelines are available for purchase from the lTU- T. Since lTU- T specifications and recommendations are widely followed by ven- dors in the telecommunications industry, those want- ing to maximize interoperability with other systems need to be aware of the information disseminated by the lTU- T. A full list of general categories is listed in Appendix C and specific series topics are listed un- der individual entries in this dictionary, e.g., S Se- ries Recommendations. See R Series Recommenda- tions chart. R-Y red-luminance. In the YUV video color model in which chrominance and luminance are separate, the color R (red) minus Y (luminance) equals V, which is used to calculate color differences. Associ- ated with this is the color B (blue) minus Y (lumi- nance) equals U. Ifboth calculations were to be zero (0), it would indicate no color (chrominance). In video engineering, R-Y (red -luma) andB-Y (blue -luma) are multiplied by defined values to derive V and U, respectively. Color difference components with luma removed are represented as R'-V' and B'-Y'. Color component removal is a mathematical approach to decomposing a YUV video signal that is useful for a variety of reasons, including as a means to reduce bandwidth for transmission and for special effects. It is used in the PAL analog video standard and CCIR 601 digital video standard. RlT 1. See realtime. 2. receive/transmit. RIW read/write. R&D See research and development. R&E 1. See Research and Education. 2. research and engineering. R&S research and statistics. 787 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary Rl signalingA type of signaling scheme commonly used in channelized voice networks in North America and Japan that is typically implemented through aTl line. It enables supervisory and address signals to be transmitted between network switches using a single frequency for supervisory (line) information and multiple frequencies for address (register) informa- tion. Tl signaling is specified in ITU-T recommen- dations Q.310 to Q. 331. See channel-associated sig- naling, R2 signaling. R2 signalingA type of signaling scheme commonly used in channelized voice networks outside North America and Japan. In association with E1 networks, it is similar to channelized T 1. R2 implementations tend to be variants ofITU-T Q.400 to Q.490 recom- mendations; there is some flexibility in the chan- nelized signaling parameters for setting the param- eters for specific countries, an important capability in the multicultural European Union. Signal types are configured as line signals and interregister signals. See channel-associated signaling, RI signaling. RA 1. radar altimeter. 2. rate area. A region desig- nated to receive products and services at described rates for the purposes of administration and billing. 3. See RealAudio. 4. Reliability Action Center. RA number See return authorization number. RA-EN See Radio Amateur Emergency Network. RAC 1. See Radio Amateurs of Canada. 2. Radio Austria Communications. Based in Vienna. 3. See re- mote access concentrator. RACE 1. random access computer equipment. 2. See Research in Advanced Communications in Europe. RACES See Radio Amateur Civil Emergency Ser- vice. raceway A duct or channel system designed to hold, protect, and direct interior wiring circuits. Raceways are typically plastic or metal modular construction, with a variety of fittings so individual sections can be interconnected and holes can be punched where needed. Raceways can be mounted on or in walls or floors. See molding raceway. RACF 1. See Radio Access Control Function. 2. See resource access control facility. rack, trayA support structure designed for the easy insertion, removal, and configuration of modular component systems. Racks are frequently equipped with rollers, although large ones may be attached to a wall for better support. They are generally as- sembled from rigid metal strips, interconnected to produce a strong open structure so the components can be quickly slid in and out of the individual bays from the front, and cabled to one another at the back. Racks are commonly used in the broadcast TV and video editing industries; they can also be found in telephone switching installations and on large com- puter networks with a variety of storage media. See distribution frame, rack unit. rack mountable A component designed to specifi- cations so it will fit easily and securely into a storage and support rack ofa standard size for components from that industry. See rack, rack unit. rackunit RU. A measure of distance based on physi- 788 cal rack structures that are common within various industries. Rack sizes have long been standardized in the power distribution, audio/visual, and portions of the retail sales industries. Racks are especially common for supporting video processors, frame synchronizers, frame grabbers, and other video editing and broadcast components. In the video industry, the rack width for rack-mountable audio and video components is typically 19 in. and the vertical rack unit (RU) is 1.75 in. Thus, a3.5-in high component would be described as having a height of2RU. See rack. racon See radar beacon. RACS 1. remote access calibration!controVcomput- ing services/system. RACT remote access computer/control terminal. rad radiation absorbed dose. A quantification of ra- diation energy that describes how much radiation is delivered to 1gofa substance by 100 ergs of energy. Radiation absorbed by body tissue is measured in roentgens. RAD 1. rapid application development/design. 2. See Radiance. 3. random access device. 4. recorded an- nouncement device. 5. remote antenna driver. radar radio detection and ranging. In its basic form, radar is a means of detecting distant or unseen ob- jects by emitting radio frequency electromagnetic waves and measuring the reflected response. As such it can operate at night, during fog, and in situations where something is too distant to be seen by unaided eyes. Radar works on the principle that radio waves will deflect offof solid or sufficiently dense objects in a way that can be anticipated or controlled so the returning signal can be analyzed for the presence of the objects, their general shape and size, and their distance. Radar is a powerful and flexible technol- ogy that has become an intrinsic aspect of navigation, reconnaissance, and imaging systems. Radar typically operates in ultra high frequencies (UHF) and microwave frequencies. See radar, his- tory; sonar; Taylor, A.H. radar, history Radar and sonar originated in much the same way in the late 1800s and the two technolo- gies still share many terms and general principles. Johann Christian Doppler (1803-1853) made impor- tant contributions to both radar and sonar history by studying the way in which compressions arising from motion could alter sound frequencies, relative to the position of the viewer (or sensing instrument). It was discovered that this characteristic was also applicable to electromagnetic phenomena like radio waves and light, resulting in Doppler radar technologies about 100 years later. The fact that electromagnetic waves could be re- flected was first demonstrated by Heinrich R. Hertz (1857-1894) in 1886. In 1904, Christian Hiilsmeyer (1881-1957) patented a "far-moving scope" which used reflected radio waves ( early radar) for detect- ing marine vessels in order to prevent collisions at sea, a system that eventually superseded searchlights for detecting nearby vessels in the dark or fog. In 1906, William R. Blair described the use ofelectro- © 2003 by CRC Press LLC magnetic oscillations to determine the incident en- ergy returning from various reflecting surfaces. By 1916, interest in radio sensing devices was spread- ing rapidly. Dominik and Scherl had invented a ra- dio echo sensing device in Europe and in 1917 Nicola Tesla wrote about radar concepts in the Electrical Experimenter in America. The earliest commercial use of radio frequencies for bouncing signals was in the 1920s and 1930s, where it was used to determine the presence of marine ves- sels and aircraft to help prevent collisions. By the mid-1930s, when cathode-ray tube displays were becoming commercially viable, radar was used in both military and commercial navigation and docu- mented in engineering textbooks. With the onslaught of World War II, interest in radar increased dramati- cally and substantial resources were devoted to its im- provement and adaptation for military purposes. Since then, radar has been adapted to many indus- tries and continues to be used for its original purpose, navigational safety, and for many diverse military and commercial applications. See radar. radar beacon A device associated with a particular location or object that is capable ofemitting aradar- range radio signal to indicate its geographic location. Apassiveradar beacon is one that sends out a ra- dar signal from time to time that can be sensed by an appropriately tuned radar receiver within range. However, it does not have a re- ceiver and cannot detect whether aradar sig- nal has been aimed in its direction. An active radar beacon includes both a radar re- ceiver and a radar transmitter. The receiver en- ables the beacon to sense a triggering pulse from a remote radar that causes the beacon to broadcast a returning signal or a series of re- turning signals. The information contained within the signal depends upon the system used, but can provide range, bearing, and, op- tionally, identification information. Because radar technology tends to be expensive, ra- dar beacons are more often installed in industrial ship- ping facilities and military applications than in con- sumer devices. Sometimes they are used in light- houses. Some less expensive radar beacons do exist, however, in the form ofpolice speed detectors. The speed de- tector determines a vehicle's speed by sending out a radar pulse that essentially acts as a beacon to any suitably tuned automobile radar detection units within range. radar detectorA device designed to detect the pres- ence of radar-range radio signals. These are used in military applications to detect or interpret radar-range communications. They are also sold for civilian use in the form ofcar-mountable devices to detect police speed-detection radar systems. The use ofradar de- tectors is regulated and prohibited in some areas. See radar, radar beacon. radar screen/scope A small display device, usually round or rectangular, which shows target signals as illuminated dots or blips. There may be grids and other alignment and location marks superimposed over the illuminated blips on the screen to aid in track- ing and location. The term radar "scope" comes from the early days when cathode-ray tubes (CRTs) were being adapted for use as oscilloscopes and various types of radar screens. See radar. radar systems Devices incorporating radio waves to detect the presence and characteristics ofdistant or otherwise unseen objects. Although radio echoes were observed in the 1920s and put into practical use in the 1930s, developments in radar guidance, detec- tion, and identification systems did not flourish until the second World War. See cavity magnetron. RADARSAT A Canadian satellite system launched in November 1995. The satellite supports a synthetic- aperture radar sensor that can deliver data in seven sizes based upon 25 beam positions. Images vary, depending upon the way the sensors are angled and the Earth viewed. Each beam position has a specific elevation angle and size. The two beam modes are single beam and multiple-beam ScanSAR. RADARSAT is part ofthe RADARSAT Network System. Radar Scope Much attention has been given to the development of radar technologies for navigation and military trackingpurposes. This radarscope, on boarda u.s. aircraft carrier, is used for aircraft approach control. Civilian and military air traffic controlpersonnelen- sure the safe and orderly flow of air traffic in com- mercial airports and on military vessels at sea. This photo was taken during NATO Implementation Force (IFOR) patrols of the waters of the Adriatic Sea. The U.S. Air Force C-14B aircraft was the first to use ground-based radio beacons for a completelyau- tomated landing in August 1937. The system offive transmittingbeacons used to accomplish thisfeat was developed by Carl J. Crane. [Detail of DoDphoto by J. Hendricks, U.S. Navy.J radial accelerationAcceleration in acircular traj ec- tory, characteristic of a spinning solid or liquid 789 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary substance. Radial acceleration is used in centrifugal separators to isolate particular particles or substances. The radial acceleration characteristics of various spi- raling entities are of interest to astronomers. In opti- cal media, radial acceleration is one of the charac- teristics measured to determine conformance with ex- pected properties or standards, along with axial ac- celeration and radial ronout. Radiance RAD. A native file format for Radiance, a public domain Unix-compatible radiosity rendering engine. The file extension . rad may be used to dis- tinguish RAD files. radiant energy Transmitted electromagnetic energy such as heat, light, or radio waves. Radiant energy is typically measured in calories, ergs, or joules. radio An appliance or other device designed for the transmission and/or receipt of radio wave communi- cations. There are many types of radio technology: amplitude modulation (AM), frequency modulation (FM), shortwave, cellular, short-range (cordless phones, wireless intercoms), etc. With increased de- mand for wireless communications, harnessing and using radio waves efficiently has become extremely important in both scientific and commercial research. More details about radio communications can be found under individual listings in this dictionary. See crystal detector, detector. Radio The publication name ofa widely-distributed Soviet electronics journal which, in June 1957, an- nounced the Soviet Union's plans to soon launch a satellite ("sputnik" in Russian), and provided details of the planned launch date, modulation techniques, and frequencies to be used. Sputnik I did in fact launch at the end of that year. See Sputnik I. RadioAccess Control Function RACF. In a PACA- E Personal Communications System (PCS), the RACF intercommunicates with a number of entities while handling the service logic, including the Ra- dio Control Function (RCF) and the Call Control Function (CCF)/Service Switching Function (SSF). See Priority Access and Channel Assignment. Radio Act of1912 With increasing interest in radio broadcasting and demand on airwaves, the U.S. Con- gress passed an act which granted the U.S. Depart- ment of Commerce the authority to regulate amateur broadcasting in order to prevent interference with government stations and to increase maritime safety, largely due to the sinking of the Titanic. See TItanic. Radio Act of 1927 As a response to the enormous rising demand for broadcast channels in the early part of the century, a conference was held to sort out the chaos. As of the Radio Act of 1912, the U.S. Depart- ment of Commerce took control of radio broadcast- ing. Zenith Radio Corporation applied for a license to operate at a frequency that was being used by other stations as well, and so was granted a license to broad- cast at a different frequency. Zenith changed frequen- cies to one that had already been granted, instead of using the one that had been licensed. In the process of investigating the violation, it was found that the Department of Commerce didn't have sufficient ju- risdiction to stop the actions of the broadcaster, and 790 one of the consequences was the creation of the F ed- eral Radio Commission (FRC) in 1927. This was later to become the Federal Communications Commission (FCC) through the Communications Act of 1934. See Communications Act of 1934, Federal Communica- tions Commission. RadioAmateurCivil EmergencyService RACES. A public emergency service provided by reserve vol- unteer communications personnel to assist regular emergency services in times of extraordinary need. The organization was established in 1952. Planning guidance for RACES deployment is provided by the Federal Emergency Management Agency (FEMA). http://www.races.net/ Radio Amateur Emergency Network Raynet. Raynet was established as a result ofa violent storm that pummeled the eastern coast of England in Janu- ary 1953. Coastal towns and villages were ravaged and more than 300 drowned. Since telephone lines were destroyed as well, there was no reliable com- munication into or out of the area during the storm. The police authorities appealed to radio amateurs to help and the Home Office gave permission for ama- teur radios to coordinate rescue services, saving many lives. Thus RA-EN was born, and grew in capabili- ties in 1989 when legislation restriction was lifted to enable the organization to provide greater help. It is now known as Raynet. Radio Amateur Satellite Corporation RASC, AMSAT-NA. This is the North American branch of the international amateur radio satellite community, a not-for-profit agency founded in 1969. Over the decades, radio amateurs have made signifi- cant contributions to the evolution of satellite broad- casting technologies in spite of the budget constraints typical of amateur organizations. AMSAT-NA sup- ports and promotes scientific research and develop- ment in radio communications satellites and space science in the public interest. The air waves, by legal right in the U.S., belong to the people, and radio ama- teurs are exercising not only their right to use this wonderful resource, but have furthered the art of wire- less communications in countless ways. AMSAT has successfully launched more than two dozen noncom- mercial radio communications satellites into Earth orbit since the historic OSCAR satellites of the early 1960s. See AM SAT, OSCAR. http://www.amsat.org/ Radio Amateurs of Canada RAC. RAC provides liaison, coordinating functions, and policy decisions for the benefit of Canadian amateur radio organiza- tions and individual amateur radio operators. http://www.rac.cal radio broadcasting Commercial radio broadcasting began in the early 1900s, arising out of the experi- mental broadcasts of inventor R. Fessenden in 1906. There were many amateur broadcasts between 1906 and 1920, including the regularly scheduled shows by Charles "Doc" Herrold, at the Herrold College of Wireless and Engineering in California, and the pre- KDKA broadcasts from the garage of F. Conrad in 1919. CFCF and KDKA are acknowledged as the first commercial stations, beginning in 1920. © 2003 by CRC Press LLC Commercial broadcasting in Europe was underway by 1913, and the Eiffel Tower still stands as a his- toric reminder of the lofty ambitions of the broadcast pioneers. It was built for the Paris World's Fair in the 1800s and there have been several attempts to remove it since then, but its usefulness as a giant antenna is one of the reasons it was preserved. Lee de Forest participated in one of the first transcontinental broad- casts from the world's largest radio tower. The Ra- dio Corporation ofAmerica (RCA), founded in 1920, is one of the best known and most influential of the early radio pioneers, and much of its history is related to the activities ofDavid Sarnoff. Sarnoff was also instrumental in forming the National Broadcasting Corporation (NBC), in 1926. The following year the Columbia Broadcasting System (CBS) was formed (originally Columbia Phonograph Broadcasting un- til William S. Paley bought out the company in 1928). From 1921 to 1922 the number of commercial sta- tions in the U.S. increased from five to over 500. In the early 1930s, record companies became nervous about competition from radio stations and began re- stricting the open broadcasting of audio recordings. From that point on, royalties and other means of en- forcing payment for broadcasts were instituted. By the late 1930s the wonderful music from bands and orchestras around the world could be heard through the magic of radio, and listeners who had never been to a theater to hear a live performance enjoyed the new form of entertainment. The advent of radio meant the eventual death ofvaudeville, but some of the vaudevillian actors, perhaps best exem- plified by George Bums and Gracie Allen, made a successful transition to radio, and eventually to TV programming. By the early 1940s, frequency modulated (FM) broadcasting, made possible by the tireless efforts of inventor Edwin Armstrong, was beginning to catch on and, while it didn't supersede AM, it provided clean, clear transmissions that were favored by pub- lic broadcast and classical music stations. The inven- tion of the transistor created a revolution in minia- turization and manufacturing. By the 1950s, radio had competition from TV broadcast stations, but unlike many technologies, it didn't lose its practicality and appeal. Radio stations in NorthAmerica still outnum- ber TV stations, and radio sets continue to be in de- mand. The next majormilestone in radio broadcasting came with Sputnik and the exploration ofspace. In 1969, American astronauts sent sound and images from the Moon to Earth. Soon communications satellites were being launched into orbit in the 1970s and 1980s. This provided a means to develop mobile communica- tions, and linked computers and radios as never be- fore. Many of the pioneer communications efforts and new technologies were contributed by amateur radio enthusiasts, most notably through the OSCAR and AMSAT satellite programs. With digital electronics, laptops, and cell phones, the importance of radio continued to grow, as wireless communications were integrated into increasingly mobile lifestyles. One of the significant recent events in radio broadcasting is the introduction of digital broadcasting, pioneered by Sweden in 1996. See AMSAT; ANIK.; CKAC; Emergency Alert System; KDKA; OSCAR; Radio Corporation of America; Sarnoff, David; radio history. radio broadcasting regulations Many different sets ofguidelines and regulations have been developed to manage radio broadcasting. Some of these were in- tended to curtail unfair business practices, such as more powerful transmitting stations deliberately drowning out less powerful ones, and some were implemented to organize and coordinate the use of limited airspace, that is, the limited availability of broadcast frequencies. Others were put into effect in wartime to shut down broadcasting almost entirely, curbing the broadcast pirates, but also curbing respon- sible amateurs. In 1963 the Emergency Broadcasting System (EBS) was established, recently replaced in 1997 by the Emergency Alert System (EAS). Several Radio Acts and later Telecommunications Acts have controlledAmerican broadcasting over the decades. The jurisdiction has changed hands a num- ber of times, from the u.S. Secretary of Commerce to the Federal Radio Commission (FRC) in 1927, to the Federal Communications Commission (FCC) in the mid-1930s. The FCC has retained its wide-rang- ing licensing and regulatory powers up to the present time. See EmergencyAlert System, Federal Commu- nications Commission, Radio Act of 1912. radio button Aphysical button on a component, or iconic button in a software program, which permits selection of only one option from a group of mutu- ally exclusive selections. Selecting anyone option automatically deselects the previous option. The name derives from the action of pushbutton radio sets in which buttons can be pretuned to selected stations, and then pushed for the desired station, one at a time. Software radio buttons are often seen on input forms on Web pages. Radio Club of America This historic amateur radio group is still operating after its birth in the early 1900s. It held its first meeting in 1909 and was founded as the Junior Wireless Club Limited in 1910 in New York City. The organization changed its name the follow- ing year to the Radio Club of America. The young members of the club successfully lobbied for the in- terests of amateur radio enthusiasts before the U.S. Senate Commerce Subcommittee. The first official meeting of the organization under its new name was in November 1911. As it grew, some of the great names in radio history became associated with the club, including Paul Godley, Edwin Armstrong, and David Sarnoff It exists for the charitable, educational, and scientific furtherance of radio communications and provides scholarship funds for needy and wor- thy students of radio communications. See Junior Wireless Club Limited. http://www.radio-club-of-america.org/ Radio Common Carrier RCC. Service providers of mobile telephone and paging services employing ra- dio technology, as opposed to land line transmissions. 791 © 2003 by CRC Press LLC . Fiber Optics Illustrated Dictionary late 1980s and the 1990s and, more recently, has in- troduced Super DLTtape technologies that provide fast transfer-rate, high-capacity storage on tape car- tridges. See Super DLTtape. Quantum Flow Control QFC. In ATM networks, a congestion avoidance scheme proposed for use on available bit rate (ABR) connections. For example, in a network in which VCI tunneling is implemented, the ATM device will send only after receiving explicit credit from a receiving ATM device at the other end of the connection. If tunneling is not used, buffer al- location and a credit manager must be included. If the buffer allocation is exceeded, noncomplying cells will be discarded. quantum. Standards QIC. An international association, established in 1987, to pro- mote the acceptance and use of quarter-inch readable/ writable data cartridge drives and media. These types of storage media are commonly used for computer backup, secondary storage, and temporary storage for files that need to be transported. More than 100 QIC standards have been developed since 1988. QIC-40, QIC -8 0, QIC-3101, and QIC- 3020 have been particularly prevalent in the tape car- tridge field, although they are now being superseded by higher capacity formats. A complete list and fuller description of each standard are available on the QIC Web site. http://www2.qic.org/ quarter wave The distance, or elapsed time, in a con- ducting line or through a conducting space, which is 90° to a wave disturbance. This information in used in the design of antennas and in the quadrature trans- mission of signals,. a crashed system upon which the database was stored). Nevertheless, QFA is much more convenient than traditional serial-ac- cess tapes. quick-break fuse A type of fuse which breaks a cir- cuit very quickly ifa surge or other anomalous elec- trical condition occurs. Quick-break fuses are espe- cially useful with electronics components, which are sensitive to electrical fluctuations and prone to damage. QuickDraw A