Fiber Optics Illustrated Dictionary interface builder about two years later, which took aesthetics, utility, and logical linking to object-ori- ented structures several steps beyond Power Win- dows, and facilitated graphical creation ofwindows, menus, tables, buttons, and much more, providing a fast and easy way to create an interface and connect- ing structures that were consistent with the NeXT application framework. An hour with the interface builder could easily equal two days ofcoding by hand with a text editor. In the 1990s, other desktop sys- tems began to come out with interface builders, an idea that has great practical value, especially as ob- ject-oriented environments became more prevalent. Some authoring systems also function as application generators, as do some programmable databases. If the software front-end that allows authoring and da- tabase configuration without programming also pro- vides an option to save code that can be accessed and manipulated, usually with atext editor, and to link to operating system or program structures, then it is a form ofapplication generator. See application frame- work. application layer In layered hierarchy network sys- tems, the layer that provides services to the applica- tions programs (as in the Open Systems Interconnec- tion [OSI]model) or the layer that runs the applica- tions themselves, depending upon the network layer design. In OSI, the application layer ensures avail- ability ofparties, may provide authentication, checks the available resources, negotiates data, privacy, and error-checking parameters, and application-level pro- tocols. See Open Systems Interconnection for achart that describes layer relationships. application program Avery broad, generic term for almost any user-level computer program. That's not to say that system administrators don't use applica- tions; they do. They just happen to be more techni- cal applications aimed at atechnical user level. Short, specific applications that do a single task or a small number of tasks are sometimes called utilities, such as a disk utility for formatting disks, or a conversion utility for changing a TIFF file to a BMP file, or a copy utility for duplicating disks. Application pro- grams commonly used in telecommunications in- clude Web browsers, FTP clients, chat clients, gam- ing clients (such as bridge, chess, Go, and casino ap- plications), compression/decompression utilities, and file translation utilities. Application Program Interface API. 1. An interapplication or intervendor interface that provides a somewhat standardized means of allowing pro- grams to talk and work together. The Apache server and the Netscape server API are common interfaces used to implement network applications services. In acompetitive environment, API conformance within consumer products is rarely perfect. By making subtle changes to aspecification in an industry-leading prod- uct, vendors often slow down the competition (e.g., faster modems) and create a short business window during which they are the only company to support a particular product or specification (i.e., a temporary monopoly). However, acertain level ofadherence to 62 standards also has competitive advantages in that it is easier for third party vendors to support a leading product. 2. In the XOpen/Architectural Framework Technical Reference Model, the Application Program Interface is one of five basic elements and one of two interface types (the other being the External Environ- ment Interface). The API is aspecification for the data link between the Application Software and the Ap- plication Platform upon which all the services are pro- vided, thus facilitating portability and interoperability among systems. The API includes the semantics, syn- tax, protocols, data structures, and other definitions necessary to ensure compatibility. See External En- vironment Interface. Application Service Provider ASP. A vendor that distributes software functionality over data networks such as telephone networks, the Internet, or local! wide area networks. To get an idea of what this means, think of the different ways in which a person can get voicemail messages. The user can get a voicemail modem and set up the mailboxes on the computer and manage the messages that are received after a call comes through to the user's premises, or she or he can get a phone with built-in voicemail capabilities. On the other hand, an ASP, such as the local telephone carrier or a third-party applications phone services provider, can set up a phone line so that if it is busy or isn't answered within acertain number ofrings, it will be redirected to a voicemail service associated with the carrier's equipment. That carrier is thus a voicemail ASP. With the tremendous growth in digital telephony and data services, it is likely that markets for ASPs will grow, especially for services that are not easy for us- ers to set up and manage themselves. See ASP Indus- try Consortium, Enhanced Service Provider. Application Software Interface ASI. A means of working within a common application interface for provision ofISDN-related digital telephony services. See North American ISDN Users Forum. Application Specific Fiber Platform ASFP. As implemented by Southampton Photonics (SPI), aplat- form comprising core technologies ofspecialty fiber design and manufacturing, fiber Bragggrating design and fabrication, and amplifier and laser technology. ASFP facilitates the volume manufacture of high- performance in-fiber components and subsystems. application-specific integrated circuit ASIC. A computer chip or small, specialized circuit designed to enable or enhance a specific type of application. As examples, ASIC video cards have been designed to drive specialized monitors, ASIC modem cards provide functionality to specialized or enhanced mo- dems, ASIC daughterboards sometimes provide hard- ware support to rendering and ray-tracing applications. applications access point AAP. In general, an access point is a device or system that allows users to ac- cess a particular type ofservice. An applications ac- cess point is one that permits access to applications software. The access point is usually instituted for the management ofresource sharing and/or for security reasons. Applications that may be shared through an © 2003 by CRC Press LLC access point typically include databases that are ac- cessed or managed by multiple users or collaborative work applications in which changes and updates are relayed to the various participants. applications processorA computerized system that can be integrated with a phone system to add func- tionality. Functions may include voicemail, Auto- mated Attendant, Call Detail, networking (packet switching), and others. See peripheral device. Applications Technology Satellite program ATS. A series (ATS-l, ATS- 2, etc.) ofsatellite launchings carried out by the U.S. National Aeronautics and Space Administration (NASA) to test payloads and study space. Five of these craft in three configura- tions were manufactured by Hughes between 1966 and 1969. See Applications Technology Satellite Pro- gram chart. Applied Computer Telephony ACT. A commercial product from Hewlett-Packard Company for integrat- ing voice and data analysis technologies on HP sys- tems. The system is used in conjunction with private branch phone exchanges to record, handle, and evalu- ate call-related transactions. See Hewlett-Packard. APPN See Advanced Peer-to-Peer Networking. approved circuit See protected distribution system. approximate discrete Radon transform ADRT. A mathematical technique used in situations where sub- stantial redundancy is expected or encountered. See discrete cosine transform, Fourier transform. APR American Public Radio. See Public Radio In- ternational. APS 1. See Advanced Photo System. 2. See Auto- matic Protection Switching. APTS Association of Public Television Stations. AQL acceptable quality level. An industry-estab- lished confidence level. Aqua A new, aesthetically appealing, customizable user interface introduced by Apple Computer with Mac OS X for PowerPC- and Intel-based platforms. SeeMacOSX. Ar symb. argon. See argon. ARA See AppleTalk Remote Access. ARABSAT A communications satellite placed into orbit in the mid-1980s. The ARAB SAT System was ~:~~:~~~sl ~~~:r~ ~:~~~;:;~~a~~f~:f :n~o:: '. cial interaction for the League of Arab States. This effort was extended in 1976 with the founding of the Arab Satellite Communication Organization (ARAB SAT). In the early 1980s, the French Aerospatiale was commissioned to manufacture three satellites. ARABSAT lA and IB were launched in the mid- 1980s. ARABSAT 1C was launched in February 1992 and ARABSAT lA and IB were turned off in 1992 and 1993. ARABSAT lC is expected to be opera- tional until 2002. ARABSAT has control stations at Dirab, Saudi Arabia, and Tunis, Tunisia. Telephony and television services are provided, according to International Standards, to the Saudi Arabia and northern Africa geographic region. Aragon,Dominique In 1820, Aragon described how an artificial magnet could be created by winding a coil around a piece of iron or steel that was carrying an electrical current. Soon after, electromagnets were developed. ARAM audio RAM. A low-cost, low-grade inte- grated memory chip suitable for digital answering machines and other inexpensive consumer products. aramid, aramid yarnA strong fibrous material com- monly used to reinforce fiber optic cables, especially those that may be subject to rough treatment such as abrasion by rodents or small pellet shots. Aramid yam is favored for its low weight, flexibil- ity, water resistance, low conductivity, and high strength properties. Aramid may be used in several parts ofa cable assembly. Most often it is a reinforcing strength member, but it may also provide the mate- rial for the central element in a fiber bundle, and the ripcord used to open cable for attaching connectors. Dupont distributes a type of aramid yarn under the Applications Technology Satellite Program Satellite Launched Notes ATS-I 1966 Spin-stabilized synchronous altitude. Electronically despun antenna. Stationed over the Pacific Ocean. Successfully photographed Earth and provided a presidential communications link for recovery of Apollo II. ATS-2 1967 Gravity gradient stabilized. Insufficient thrust resulted in an elliptical orbit and it lost orbit after only 880 days. ATS-3 1967 Synchronous orbit. Mechanical despun antenna, color camera that photographed tornados in 1968 and an eclipse of the Sun in 1970. ATS-4 1968 Gravity gradient stabilization in synchronous altitude. Failed to reach intended orbit and lost orbit in 1968, two months after deployment. ATS-5 1969 Synchronous orbit. Gravity gradient booms for stabilization didn't deploy correctly, but some of the experiments were successful. It was retired in 1984. 63 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary well-known tradename Kevlar. See Kevlar, swelling tape. Aramid Yarn in Fiber Optic Cable In a typicalfiber optic cable assembly, the aramid yarn layer (1) provides strength and strain relief It is often inserted between the outer strength member and an inner supporting structure, such as a water-resis- tant tube. A ripcord (2) may be provided to make it easier to peel back the layer in preparation for add- ing a connector. ARB 1. Administrative Review Board. Established in 1996 by the U.S. Secretary of Labor within the Department of Labor. 2. Air Resources Board. 3. See all routes broadcast. arcA very bright electrical discharge across a gap in a circuit. In fiber filament fusion splicers, carefully controlled, electrode-generated arcs are used to clean and heat the ends to be spliced so they will fuse into a continuous light-guiding path. See arc lamp; Aryton, Hertha Marks; fusion splice; Poulsen arc. ARC See Ames Research Center. arc converter A device used to convert direct cur- rent (DC) into undamped or continuous wave radio frequency (RF) signals. This technology was used in early radiotelegraphy. Many aspects of global radio communications in the early 191 Os were based upon this technology. See Poulsen arc. arc lamp An electrical lamp that exploits the ten- dency of electrons to jump a gap in a circuit, which can be harnessed to produce an intense light under certain circumstances. It was invented by Sir Humphrey Davy in the early 1800s and came into widespread commercial use in the late 1870s when it was incorporated into street lamps. Arc lamps are important in optical 'etching.' Expo- sures from strong light sources can be used to chemi- cally alter substrate materials through a template mask so that some of the materials are removed and some remain. In this manner, mercury arc lamps have been used in the semiconductor industry for circuit design through optical lithography. This is a technol- ogy that may someday be superseded by higher-pre- cision electron-beam and laser etching techniques. Archie Network archiving software developed by Peter Deutsch, Alan Emtage, and Bill Heelan. Named for the word archive, Archie is an Internet query tool that tracks the contents of anonymous ftp sites. It was introduced at McGill University, Canada, in 1990. Archie allows users to retrieve a list ofFTP locations by submitting file search criteria to an Archie server. See Veronica. Archimedes (ca. 287-212 BC) A Greek mathemati- 64 cian and inventor born in Sicily who made contribu- tions to our understanding of volume and displace- ment, and who created the mathematical treatise "Measurement of the Circle" in which he described the calculation of the ratio ofacircle's circumference to its radius. See Archimedes' principle. Archimedes' principleA body immersed in fluid is buoyed up by a force equal to the weight of the fluid displaced. (This principle is humorously illustrated by actor Gary Oldman in a bathtub in the Cinecom Entertainment movie production of "Rosencrantz and Guildenstem Are Dead.") architect One who designs a layout or topology, such as a building layout, circuit board architecture, net- work routing system, etc. The architect frequently is also the one who drafts the technical drawings asso- ciated with the layout and mayor may not check elec- tronics codes, building codes, or other regulations as- sociated with the design. architecture The design and layout ofa process, sys- tem, or facility. The architecture involves the overall plan and topology, in addition to the relationships and interconnections between the individual parts. It may also include the direction of information paths or movement within the system. Good architectures usu- ally try to incorporate, or at least balance, flexibility, robustness, efficiency, and scalability, whether it be the design ofa building or ofa microprocessor chip. See topology. archivalA format, medium, or protective system de- signed to facilitate preservation. Archival papers and plastic sleeves are acid-free, or free ofplastics that may change the information or degrade rapidly. Ar- chival data storage formats are nonvolatile (magnetic media such as video tapes, audio tapes, floppy dis- kettes, etc. are not very stable over time and may be damaged by proximity to magnets) and resistant to damage and degradation. In the data industry, archi- val file formats are as important as the materials on which they are stored, as the information is useless if it can no longer be read or deciphered. archiveArepository of records or files. A backup or duplicate of information made to preserve or prevent loss in compressed or uncompressed form. AD archive generally contains information that needs to be kept over time, for one reason or another (legal, histori- cal, etc.). Many archives are seldom or ever accessed. Computer data archives are becoming more preva- lent and offer many search and retrieval advantages over traditional paper-based archives. See anony- mous FTP, Archie, archival, FTP. archiverA term for software tools that are designed to store files in such a way that they take a minimum of space and can be retrieved, reconstructed, and viewed at a later date. Software archivers often in- clude compression algorithms and switches to allow an archived file to be scanned for header informa- tion without decompressing it. The degree of com- pression possible is very dependent upon the inter- action between the type of compression algorithm and the type of data being compressed. Common soft- ware archivers include zip, lharc, Stuffit, and tar. © 2003 by CRC Press LLC archiving The process ofstoring infonnation, com- pressed or uncompressed, encoded or not encoded, such that it can be accessed and viewed at some fu- ture date, if needed. Archiving involves selecting a storage fonnat, medium, and location and carrying out occasional or scheduled consolidation and orga- nization of the objects or information. One of the big issues with archiving, besides space, is the develop- ment of efficient search and retrieval methods that make it possible to find a desired piece ofinfonna- tion in a vast amount of data. See archival, archive, database, FTP. ARCnet Attached Resource Computer network. A popular pioneering local area network (LAN) devel- oped by Datapoint Corporation in 1977 for use with thin coaxial cable. Incorporating a modified Token- Ring passing scheme, ARCnet provides high-speed baseband communications at 2.5 Mbps with either a bus or star topology. ARCnet became standardized as ANSI 878.1. Although not as widespread as it once was, ARCnet has been upgraded to include transmis- sion over copper twisted pair wire and fiber optic cables. Arcstar The brand name for the Nippon Telegraph and Telephone Corporation's (NIT) global services including NTT Worldwide Telecommunications Cor- poration, NTT Europe, ntta.com and Asian branches. These include managed bandwidth, Frame Relay, and Internet Protocol (IP) virtual private networks (VPNs). See Nippon Telegraph and Telephone Cor- poration. ARD 1. advanced research and development. 2. See Automatic Ring Down. ARIADNEt The ARIADNE network, an academic and research network operated out of Athens, Greece by NCSR Demokritos, a physics and sciences re- search association. http://www.ariadne-t.gr/ Ardire-Stratigakis-Hayduk algorithm ASH. A lossless compression algorithm, named after its cre- ators at Western DataCom, developed between 1990 and 1993. It was intended for use over synchronous data communications with varying media character- istics. Unlike asynchronous transmissions protocols, framed data can contain a very large number of bits and does not have to be timed with start and stop bits. ASH provides a means to provide good compression ratios on various types of traffic in a multiuser net- work. ASH incorporates interesting concepts from artificial intelligence. By using pattern-matching and predic- tive algorithms, data not yet transmitted and noniden- tical strings can be processed and evaluated. As part of the compression methodology, ASH uses an Oc- currence Optimized Codebook (DOC) for fast-cache access to commonly occurring tokens and strings. ASH safeguards against data expansion and latency. A patent has been sought for the ASH technology. See Lempel-Ziv- Welch. ARDIS A commercial packet-switched nationwide wireless data communications service developed in the mid-1980s by Motorola and International Busi- ness Machines (IBM) and now owned by Motorola. It was originally developed for field technicians and is appropriate for short messages and quick database lookups for a variety of applications. ARDIS is some- what similar to CDPD except that it is a data-only service. It is used for wireless faxing and realtime messaging with any Internet address worldwide. ARDIS can be accessed through laptops, and per- sonal data assistants. See RAM Mobile Data. ARE See all routes explorer. area code Athree-digit code in a phone number that designates the region. See North American Number- ing Plan (NANP). See the Appendix for a chart. area code restrictionA service for enabling the sub- scriber to deny telephone calls to specified area codes. It is not a blanket restriction as in some long-distance call-blocking services. The service is useful in offices and other environments where it is othetwise diffi- cult to monitor phone use. area network See local area network, metropolitan area network, wide area network. Area of Service ADS. The geographical area sup- ported by a vendor, carrier, or service provider. Arena 1. The name of an HTML3 browser from the World Wide Web Consortium (W3C) designed as a proof-of-concept demonstration tool for HTML+ ideas preceding HTML3. ARES See Amateur Radio Emergency Service. ARF See Alternate Regulatory Framework. argon (symb. - Ar) Argon is a colorless, odorless gas used in light bulbs. Argon plasma arc lamps can pro- vide a continuous radiation source covering a broad spectrum from ultraviolet to infrared suitable for test- ing solar energy components for use in satellite com- munications. See argon laser. argon laser A type of gas laser that primarily uses argon gas. This common type oflaser can be used to produce green and blue light, which is useful for cre- ating laser light show effects. It is similar to a kryp- ton laser, except that argon produces a little more light. Argon is sometimes combined with krypton gas to produce an argon-krypton hybrid. Argon la- sers are typically water-cooled. ARI Automatic Room Identification. A telephony service used especially in the hotel/motel industry to identify call locations. ARm See Association of Radio Industries and Busi- nesses. Ariell Historically, the first U.K. satellite project to study the ionosphere, launched in April 1962. The satellite's orbit decayed in 1976. ARIES 1. Angle-Resolved Ion and Electron Spec- troscopy. 2. The name ofa commercial satellite ser- vice. See Constellation Communications, Inc. 3. See Australian Resource Information and Environment Satellite. ARINC-429 Digital Information TransferSystem DITS. DITS is a digital point-to-point hardware ar- chitecture and data specification for describing a digital bus for device communications for the aeronautics industry. The transmission hardware is based upon twisted-pair wires with one transmitter connected to one or more receivers. The data protocol is based 65 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary upon 32-bit words consisting ofa data portion and a label identifying the nature of the data. Development of the DITS specification and ARINC-compatible products aided in the commercialization of digital communications for aeronautics devices and facili- tated the development of modular, off-the-shelf prod- ucts. See ARINC-629. ARIN C-629 A commercial civilian communications protocol based upon a central twisted-pair bus archi- tecture which can accommodate up to 120 peripheral devices or terminals at a 2-MHz bus rate. ARINC- 629 evolved from ARINC-429 , which was developed in the 1970s. ARINC products are manufactured by Excalibur Systems, Inc. ARINC Incorporated An organization formally es- tablished in 1929 by Louis Caldwell and representa- tives of four major airlines as Aeronautical Radio, Inc. ARINC was established to be the dominant nongov- ernment single licensee and coordinator of radio com- munications. Upon its formation, the Federal Radio Commission (FRC) transferred to ARINC the respon- sibility for aeronautical ground radio stations, thus providing a within-the-industry means of administrat- ing aeronautic rules and regulations established by theFRC. ARINC continues to coordinate airline industry tele- communications activities, communications, and in- fonnation processing systems. It publishes standards of relevance to avionics systems and analog and digi- tal equipment. ARISE 1. See Advanced Radio Interferometry be- tween Space and Earth. 2. American Renaissance in Science Education. 3. Applications Reform in Sec- ondary Education. ARISS See Amateur Radio International Space Sta- tion. Aristote Association A French association of orga- nizations and frrms engaged in the development of telecommunications and data transmissions technolo- gies. The Secretariat is located at the Ecole Polytechnique in Paris, France, with seminars and workshops held at the Arago and Poincare amphithe- aters. http://www-aristote.cea.fr/ ARISTOTELES Applications and Research Involv- ing Space Technologies/Techniques Observing the Earth's Fields from Low Earth-Orbiting Satellites. A joint project of NASA and ESA carrying out scien- tific research data gathering on the Earth's gravity and magnetic fields. It is equipped with a Global Posi- tioning Service (GPS) receiver, gradiometer, and sca- lar magnetometer. Arkay CT-650 A commercial computer based upon a description ofa paperclip computer, (a homebrew digital computer that could be constructed out of materials found around a home). ARL 1. Air Resources Laboratory (NOAA). http://www.arl.noaa.gov/ 2. See Association of Re- search Libraries. armature A portion ofa magnetic circuit typically consisting of a conducting material, such as wire, wound around a core, which is moved within a strong magnetic field to create current. If the armature 66 revolves, the wound material interacts with the mag- netic lines of force, in asense, cutting in and out, and the current generated by this interaction can be drawn out. The arrangement is used in generators and alter- nators, where the current may be drawn out by brushes. See coil. Armed Forces Communications and Electronics Association AFCEA. An international nonprofit professional association for communications, elec- tronics, and intelligence. Founded in 1946, the asso- ciation has over 40,000 individual and corporate members in government, industry, and military sec- tors. AFCEA publishes SIGNAL Magazine, techni- cal papers, and books. http://www.afcea.org/ ARM See American Radio Museum. armor 1. Defensive or protective covering. 2. A type ofheavy-duty waterproofing or other shielding used especially in underwater or underground installations. 3. Heavy shielding to protect facilities, equipment, and personnel from radiation or chemical contami- nation. 4. In computer technology, heavy security measures taken to keep users offa system, which may range from inaccessible facilities to extra software measures taken to discourage unauthorized intrusion. armor-plated Aphysical or administrative high se- curity system which the administrators deem to be virtually impenetrable. Highly resistant to access or tampering. Bullet-proof. armored cable See aramid yarn; cable, annored. armoring, ballistic A strong armor layer (e.g., coated steel) used to protect aerial components and cables from shotgun pellet intrusion. Ballistic annoring for fiber optic cables is generally about 0.25 mIn thick. Sometimes dual armoring layers are used, in addi- tion to aramid fibers. The ballistic energy from pellets hitting a cable is dis- sipated by the steel armoring. Increased protection against larger pellets is offered by aramid fibers that cushion the fibers from the impact ofa pellet. ZETABONTM is an example ofasteel-annored cable distributed by Dow Chemical Company. See aramid; cable, armored. Armstrong, Edwin Howard (1890-1954) Agifted American researcher who invented the superhetero- dyne circuit and frequency modulation (FM). Arm- strong was not only a good inventor but also a good theoretician; he was one of the few people who un- derstood, on aphysics level, many of the new inven- tions that were making possible the development of wireless communications. In October 1914, Armstrong was awarded a patent for his wireless receiving system (U.S. #1,113,149). In the 1920s, he contested Lee de Forest in the in- vention ofregeneration, but de Forest won the suit. After many years of painstaking research against con- ventional wisdom and the negative predictions of mathematicians and engineers, Armstrong proposed a method ofwave modulation that varied the fre- quency rather than the amplitude ofa wave. He was awarded a patent for FM radio signaling in Decem- ber 1933 (U.S. # 1,941,066). Armstrong waged a long and tragic legal battle with © 2003 by CRC Press LLC RCA over his patents to the FM technology which were posthumously upheld in his favor. During World War II, Armstrong furthered the art of radar transmis- sion by suggesting the use ofFM signals, rather than the short pulse radar bursts that were used at the time. His ideas are now commonly incorporated into fre- quency modulated (FM) radio, television, and radar transmissions. See frequency modulation, heterodyning. AROS I. Amateur Radio Observation Service. 2. Amiga Research OS. A project initiated in the mid- 1990s to update, bug-fix, and enhance the Amiga Operating System. http://www.aros.org/ ARP See Address Resolution Protocol. ARPA Advanced Research Projects Agency. See Defense Advanced Research Projects Agency. ARPANET Advanced Research Projects Agency Network. The historical basis of the Internet, ARPA- NET was originally discussed by the ACM in 1967, presented to ARPA the next year and put into opera- tion in 1969. The frrst widespread demonstration of ARPANET occurred at a Computer Communications conference in 1972, and ayear later ARPANET traf- fic had grown to millions of packets of data transfer per day. By 1975, the ARPANET had been transferred to the Defense Communications Agency (later the Defense Information Systems Agency). In 1982, ARPA endorsed TCP/IP as its protocol suite. In 1983, ARPANET split into MILNET and ARPA- NET (mandated to use TCP/IP), which together formed the Internet. Each was given a network num- ber, and gateways were installed to provide packet forwarding between them. ARPANET was officially discontinued in 1990, largely due to the evolution of the Internet. See ARPA, BITNET, lANA, NSFNET, NEARNet, SPAN. ARQ See automatic retransmit request. array A type of data organization structure com- monly used in programming. An array consists of an ordered list or matrix of information which can be visualized as 2D or 3D tables of information con- tained in cells which often have common character- istics, such as the size of the data cell (although the data in the cells may vary in length). Arrays form the structural basis for many types of databases, includ- ing tables and lists. Many software programs have built-in array-handling functions to automate com- mon ways in which arrays are manipulated. array antenna I. An antenna with a number of di- recting, reflecting, or other elements arranged in a more-or-Iess regularly spaced, often symmetrical pattern. See antenna. 2. One antenna in an array of antennas that are organized and connected in such a way as to significantly boost power, range, and per- formance. These powerful antenna systems are used for picking up weak signals as in astronomy and mili- tary applications. ARRL See American Radio Relay League. ARRL Monitoring SystemA policing system of the American Radio Relay League to monitor and main- tain the correct, licensed, and responsible use of ama- teur radio frequencies and procedures. For the most part, the amateur radio community successfully seeks to be self-policing, but there are times when unau- thorized use reaches problematic levels or originates in countries that are not regulated by the U.S. Fed- eral Communications Commission (FCC), at which time the ARRL will document the problems and call for assistance from appropriate domestic and inter- national agencies. See American Radio Relay League. ARRN Amateur Radio Repeater Network. ARS See Automatic Route Selection. ARSR See Air Route Surveillance Radar. articulation Clear utterance or playback of sounds - the degree to which reproduced or transmitted sounds are clear enough to be understood by a lis- tener. Mumbling is poor speech articulation. When people say "Testing, testing, " on a sound system, they are testing not only circuit functioning and vol- ume but also the clarity of the sound and capability of conveying a message. Articulation does not have to be high fidelity to be understood. It depends in part upon the ability of the recipient to perceive and un- derstand the message, and may not have to match perfectly the original. This is an important aspect of data communications as well. When conversations are converted from analog to digital, through a pro- cess called sampling and quantization, it is important to determine how much of the information is needed in order for the communication to be understood by the recipient. This information can be applied to com- pression and decompression systems for speeding up transmissions. See fidelity, intelligibility. articulation index AI. A scale from 0 to 1 that pro- vides an obj ective reference for the intelligibility of voice signals expressed. AI is quantified in terms of the percentage of speech units understood by a lis- tener when the units are presented out of context. The index is a useful measure for testing and comparing voice transmission and speech compression/decom- pression technologies. See articulation. artificial intelligence AI. Insights or behaviors at- tributed to an entity, usually a machine, that is not traditionally perceived by humans as having the ca- pability to think in ways that involve problem-solv- ing, insight, and other uniquely human characteris- tics. The field ofartificial intelligence has spawned many useful approaches, languages, techniques, and programming algorithms. Expert systems, neural net- works, robotics, vision systems, and natural language processing all have their origins in AI research. People interested in artificial intelligence come from a diverse range of backgrounds. The origins ofartificial intelligence, as they apply to computers, trace back to the 1950s, though Ada Love- lace proposed in the 1800s that "thinking machines" could be programmed to create music or art. Pioneer researchers include A. Turing, J. McCarthy, and N. Wiener. See expert systems; Intelligent Networks; Lovelace, Ada; robotics. Artron artificial neuron. The familiar name for an electronically simulated neuron used in a maze-run- ning robotic mouse in the early 1960s. See Melpar model, neural network. 67 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary AS 1. See Applicability Statement. 2. See autono- mous system. as is Atenn applied to products that are bought and sold with no implied or stated warranties. Condition may be guessed by inspecting and trying the equip- ment, but there is no way to know the completeness, remaining useful life, or technical functionality of the equipment. See fair, good. AS&C 1. Advanced Systems & Concepts. A division of the U.S. Department of Defense associated with the Deputy Under Secretary of Defense (DUSD). ASCO, the DTRA Advanced Systems & Concepts Office, encourages seed projects for technologies developed to counter threats to national security. 2. Alann Surveillance and Control. AS-Interface, Actuator Sensor Interface, AS-i. An open network protocol for automating actuator and sensor control for industrial applications. It can op- erate as a controller or as a stand-alone automation support bus. It may also be used with higher level field buses to enable remote input/output operations. A single AS-i v2.0 master can support up to 124 ac- tuators/outputs and 124 sensors/inputs. See actuator, INTERBUS, PROFffiUS. ASA 1. See Acoustical Society of America. 2. Assis- tant Secretary of the Army. ASARS See Advanced Synthetic Aperture Radar System. ASC 1. advanced switching communications. 2. Aeronautical Systems Center. A U.S. facility lo- cated at Wright-Patterson AFB. Science and technol- ogy programs are carried out in the Wright and Arm- strong Laboratories. Ascend InverseMultiplexing AIM. An in-band net- working protocol from Ascend Communications that manages interconnections between two remote in- verse multiplexers. Ascend Password Protocol APP. A network User Datagram Protocol (UDP) used in servers to respond to password challenges from external authentication servers. APP Server utilities are available from As- cend for a wide variety of computer platforms. ASAI See Adjunct Switch Application Interface. ASAPI Advanced Speech API. An open, cross-plat- fonn speech applications programming interface de- veloped by AT&T. ASCA See Advanced Satellite for Cosmology and Astrophysics. Ascend Password Protocol APP. A User Datagram Protocol (UDP) network security protocol defaulting to port 7001. ascending node Intersection of a satellite's orbital plane with the Earth's equatorial plane. Ascn (as-kee) The American Standard Code for In- formation Interchange was developed by the Ameri- can National Standards Institute (ANSI). Also known as ASCII International Telegraph Alphabet 5, ASCII is the most widely used computer character set en- coding scheme currently employing seven bits, thus making a total of 128 possible characters/symbols. ASCII is mainly suitable for English language com- munications. Since it is very limited in its letters and 68 symbols, many extensions to ASCII have been incor- porated into key mappings on various computers to include symbols and western European characters. Sometimes called extended ASCII (even though the extensions aren't standardized), these 8-bit encodings provide 256 possible characters, but the higher 128 characters are not usually compatible across plat- forms. See EBCDIC, Unicode. See the Appendix for an ASCII chart. ASCn editorA text editing tool that handles basic, simple characters standardized as ASCII text, which are cross-compatible and transferable over almost all seven-bit-compatible systems, which includes most computer networks. Since the ASCII standard does not support style attributes (bold, underline, oblique, etc.), it cannot be used for extensive formatting. Due to the limitations and simplicity of its character set, ASCII editors are very fast. They are also good for writing computer source code, which typically needs speed and compatibility more than style tags. If you require style tags and indentation for text for- matting, and want to transfer the documents across applications or platforms, the best supported format that includes them is Rich Text Fonnat (RTF), also known as Interchange Format (developed by Micro- soft and supported across its products). It's not 100% compatible across platforms, but it's pretty close and can be read and written by most word processors (with import and export menu options). Another good format for transferring more complex documents is generic Adobe PostScript, which includes not only text and style support, but image positioning, layout effects and more, or its cousin, Adobe Acrobat's Por- table Document Format (PDF). When designing Web pages with links to download- able files, there should be more than one format avail- able. If all Web site managers were to include these three: an ASCII version, an RTF version (which can be read into virtually any popular word processor), and a PostScript or PDF version, then the needs of low-end and high-end users would be well met, and at least one of the files would be accessible to virtu- ally everyone using the Web. See appendix for an ASCII chart. ASDSP application-specific digital signal processor. See digital signal processor. ASE Application Service Element. An element of an application layer protocol in the Open Systems in- terconnection (OSI) layered network model. It is combined with other elements to form the complete protocol. See Open Systems Interconnect. ASFP See Application Specific Fiber Platform. ASH See Ardire-Stratigakis- Hayduk. Asia DAB Committee,Asia DAB ADC. A nonprofit association working in conjunction with the World DAB Forum to promote, support, and coordinate the implementation of digital radio broadcasting tech- nologies in Asia. Digital Audio Broadcasting (DAB) promises to significantly change and improve the quality and richness of programming information available to consumers. See Digital Audio Broadcast- ing Forum. http://www.asiadab.org/ © 2003 by CRC Press LLC Asian Mobile Satellite System AMSS. Asatellite- based mobile phone system of Asia-Pacific Mobile Telecommunications Satellite Pte. Ltd. The system was supplied by Hughes Space and Communications International, Inc. It operates in the L-band to pro- vide a mobile infrastructure for communications in Asian-Pacific regions from Japan to Pakistan. Asia is a world leader in many aspects of wireless com- munications. ASI 1. Advanced Study Institute. 2. artificial sens- ing instrument. 3. Astronomical Society of India. ASIC See application-specific integrated circuit. ASK See amplitude-shift keying, modulation. Ask Jeeves A prominent and specialized freely ac- cessible search engine on the Web, Ask Jeeves uses natural language processing to search information based upon sentence-like queries. Finding information on the Internet can be a daunt- ing prospect and many lexical search engines search on keywords or conditional statements and provide thousands or millions of hits on the queried topic. In contrast, Ask J eeves will parse out English-like que- ries and provide a selective group of good hits from a variety of search sources based upon intelligent search algorithms, a process central to data mining. See data mining; search engine, Web. See appendix for a search engine chart. ASL Adaptive Speed Leveling. A U.S. Robotics mo- dem term for adjusting the speed ofa serial transmis- sion, depending upon line conditions, to optimize the transfer of data. ASN 1. Abstract Syntax Notation. See ASN.l 2. See Autonomous System Number. ASN.l Abstract Syntax Notation 1. An ISO/ITV-T standard machine- and implementation-independent language defined in 1988 for the description of data, to facilitate the exchange of structured data among applications programs. ISO 8824, lTV TS X.208. ASP 1. Abstract Service Primitive. In ATM network- ing, an implementation-independent description of user/provider interactions, as defined by the Open Systems Interconnection (OSI). 2. Adjunct Service Point. A network feature of peripherals designed to respond intelligently to processing requests. 3. admin- istrative service provider. SCSA term. 4. analog sig- nal processing. 5. See AppleTalk Session Protocol. 6. See Application Service Provider. 7. See ATM switch processor. 8. Attached Support Processor. 9. Association of Shareware Professionals. ASPIndustry ConsortiumAn informational global advocacy group supporting Application Service Pro- viders (ASPs), their delivery associates, and their customers, founded in May 1999. The group provides research information, education, and strategic guid- ance. The ASP Consortium currently serves hundreds of members in more than two dozen countries. It is managed by Virtual, Inc., a high-tech industry inte- grated management and marketing firm. http://www.aspconsortium. org/ aspect ratio The relationship of the proportions of the width to the height, usually ofa rectangular form. A two-to-one aspect ratio, for example, is commonly written as 2: 1. The aspect ratios of televisions and monitors are similar, but cinematic films, which are shown in theaters with panoramic screens, have a much greater width-to-height ratio. This is why letterboxed films have a dark strip on the top and bottom to preserve the full width of the image. Unletterboxed films have been modified to remove part of the picture from the sides. See anamorphic. ASPI See Advanced SCSI Programming Interface. ASQ 1. Administrative Science Quarterly. 2. Ameri- can Society for Quality. ASQ sponsors ASQNet. http://www.asq.org/http://www.asqnet.org/3. Appli- cant and Student Query. A system to automate the verification of student admissions information. 4. Ap- plication Status Query. A Web-based tool for allow- ing applicants to check their status, developed by DLAHROC. http://www.hroc.dla.mil/5. Automated Status Query. ASR 1. Access Service Request. A request sent to a local exchange carrier (LEC) for access to the local circuit. 2. See Airport Surveillance Radar. 3. Auto- matic Send/Receive. A system that can send and re- ceive messages unattended. 4. See Automatic Speech Recognition. assemblerA program that converts symbolic assem- bly language program code into machine instructions that can be directly executed by a computer CPU. On early microcomputers, in the 1970s, most serious pro- gramming was done with an assembler. assembly language A low-level symbolic computer language which structurally and mnemonically fits somewhere between machine code and higher level languages such as C, BASIC, Java, and Perl. Lan- guages like BASIC and Perl are typically run in in- terpreted mode (although compilers exist for almost everything, if you really want one). When compiled and assembled, C and assembly language are con- verted into machine language, which typically con- sists of the binary digits one and zero and is very dif- ficult (for normal folks) to read and debug. By coding in assembly language (which is difficult for most folks) and then using an assembler, a soft- ware utility to convert to machine code, the program can often be optimized to run faster and may be more difficult to reverse-engineer. See symbolic code. assigned frequency See Federal Communications Commission. assigned numbers A sequential numbering system administrated by IAN A to organize and assist in the search and retrieval of Request for Comments (RFC) documents. See lANA, Request for Comments. Association Control Service Element ACSE. An International Standards Organization (ISO) applica- tion layer service for establishing a connection, as part of the Open Systems Interconnection (OSI) model. Association for Computing Machinery ACM. A well-known trade association serving more than 80,000 computing professionals in over 100 countries. Members participate in the exchange of ideas, dis- coveries and information in many areas of academia, government, and industry. The ACM was founded in 1947. http://www.acm.org/ 69 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary Association for Cooperation in Telecommunica- tions Research in Switzerland ACTRlS. A telecom- munications research initiative for precompetitive research in telecommunication technologies, formed in 1995 by the Pro Telecom partners, an association of Swiss telecommunications companies. ACTRIS is centered in the Multimedia Communications Lab in Basel, Europe's largest experimental platform. It serves major Swiss telecom companies, as well as those in neighboring countries. The main objectives are to promote research and education in telecommu- nications. Association for Education in Journalism and Mass CommunicationAEJMe. Aprofessional association ofpost-secondary journalism and mass communica- tions educators and administrators. http://www.aejmc.sc.edu/ Association for Educational Communications and Technology AECT. An organization committed to providing communication among professionals with a common interest in using technology for education. http://www.aect.org/ Association for Information and Image Manage- ment AIIM International. AIIM was established in 1943 as the National Microfilm Association. It sup- ports users of document and content technologies with information about technologies and suppliers. AIIM seeks to provide practical, unbiased educational information to its global membership through con- ferences, articles, and member participation. http://www.aiim.org! Association for Information Systems AlS. A pro- fessional organization serving as a global resource for academics specializing in information systems, founded in 1994. AlS publishes The Journal of the AIS and The Communications of the Association for /nfo177zation Systems. http://www.aisnet.org/ Association for Interactive Media AIM. A Wash- ington, D. e based nonprofit trade association dedi- cated to promoting consumer confidence and govern- ment support of interactive media products and re- lated technologies. http://www.interactivehq.org! Association for Literary and Linguistic Comput- ing ALLe. An association for supporting the use of computer technologies for studying languages and literature, founded in 1973. ALLC publishes the Lit- erary andLinguistic Computing journal through Ox- ford University Press. The association sponsors an annual convention in cooperation with the Associa- tion for Computers and the Humanities (ACH). Association for Maximum Service Television MSTY. Aprofessional association of local television stations established in 1956 to undertake studies to support development of Federal Communications Commission (FCC) television technical standards. In 1962, MSTV provided a voice for new television technologies in the All-Channel Receiver Act. In 1987, the association brought together broadcast or- ganizations to petition the FCC to look into high-defi- nition television (HDTV) and participated materially in the Advisory Committee on Advanced Television Services (ACATS). In 1996, the Consumer Electronics 70 Manufacturers Association (CEMA) and MSTV cre- ated the Model HDTV Station Project, licensed as WHD- TV, to educate broadcasters on the implemen- tation of digital television services. MSTV seeks to preserve and improve the technical quality of free, universal, community-based televi- sion service to the American public. MSTV provides its members with information on new technologies and policies, particularly digital television advance- ments and implementation information. See Ad- vanced Television Test Center, Advisory Committee on Advanced Television Services, Digital Television Station Project, Inc. http://www.mstv.org! Association for Women in ComputingAWe. A not- for-profit professional association founded in 1978 to promote the advancement ofwomen in comput- ing. http://www.awc-hq.org! Association ofCollege and University Telecommu- nications Administrators ACUTA. An international nonprofit educational association serving colleges and universities and representing vendors serving the educational market. ACUTA sponsors the award for Institutional Excellence in Telecommunications and publishes news and a quarterly journal. http://www.acuta.org! Association ofCommunications Technicians ACT. An organization to support technicians working in the field of communications. ACT is a member of the PClAFederation of Councils, representing commer- cial and private mobile radio service communications industries. Association of Competitive Telecommunications Suppliers ACTS. ACanadian-based association rep- resenting telecommunications equipment manufac- turers and suppliers in order to support and encour- age market competition. Association of Computer Professionals ACP. A U.K based nonprofit organization providing courses that lead to recognized qualifications, founded in 1984. http://www.btinternet.com!-acp/ Association of Computer Support Specialists ACSS. Atrade organization assisting and represent- ing those who install, support, maintain, test, and re- pair computing systems. Members include vendors and manufacturers who provide customer support, as well as independent consultants and those who pro- vide equipment and services to support these special- ists. http://www.acss.org/ Association of Computer Telephone Integration Users and SuppliersACTIUS. Atrade organization in the United Kingdom which promotes awareness and acceptance of computer-telephone integration (CTI) technology through campaigns and educa- tional programs. Association ofIndependents in Radio AIR. Anon- profit organization representing and promoting the interests ofa diverse membership ofaudio produc- ers, audio artists, radio broadcast stations, and me- dia arts centers. AIR sponsors online discussion groups, group health benefits, and the AIRSPACE journal. See Producers Advocacy Group. http://www.airmedia.org! © 2003 by CRC Press LLC Association of Radio Industries and Businesses ARIB. A research and development organization, headquartered in Tokyo, Japan, that studies radio waves and developing radio systems and industries in telecommunications and broadcasting, in order to promote public welfare. A number of committees work under ARIB, including the Infrared Communi- cations Systems Study Committee. Association of Research LibrariesARL. Anot-for- profit organization of the leading research libraries in North America. The ARL furthers and promotes the evolution of research libraries and scholarly com- munication. http://www.arl.org/ Association of Science-Technology CentersIncor- porated ASTC. An organization of science centers and museums dedicated to fostering the public un- derstanding ofscience through innovation and excel- lence. ASTC was founded in 1973 and has members worldwide in more than three dozen countries. http://www.astc.org/ Association of Wireless System Integrators AWSI. An organization to support integrators working in the field ofwireless communications. ACT is a member of the PCIA Federation of Councils, internationally representing commercial and private mobile radio service communications industries. ASSP 1. acoustics speech and signal processing. 2. application-specific standard product. An inte- grated circuit designed for a specific application. ASSP Magazine Apublication of the IEEE devoted to signal processing. ASSTA See Australian Speech Science and Technol- ogy Association Incorporated. Assured LinkA telephone link meeting certain mini- mum transmission, loss (5.5 dB in the 300- to 3000- Hz bandwidth range), and service standards for a communications circuit for voice grade analog sig- nals and sometimes one-way digital signals. See Ba- sic Link. AST See Automatic Scheduled Testing. astatic galvanometer A device developed by Will- iam Thompson (Lord Kelvin) in 1858 to overcome the limitations ofearlier instruments that were sub- ject to interference from the Earth's magnetic field. Unlike previous galvanometers employing one needle, the astatic galvanometer uses two needles, each with a separate coil. The needles are oriented so that north and south poles effectively cancel out the Earth's magnetic interference. See galvanometer. ASTC I. See Association of Science-Technology Centers. 2. Australian Science and Technology Coun- cil. An association of professionals involved in tech- nical and business communications. 3. Australian Society for Technical Communication Inc. A non- profit society ofprofessionals involved in commu- nicating technical information. ASTER Advanced Spaceborne Thermal Emission and Reflection Radiometer. A Jet Propulsion Labo- ratory (JPL) satellite imaging instrument project. Since 1998, ASTER has been obtaining moderate to coarse detail maps of Earth's temperature, emissiv- ity, reflectance, and elevation characteristics. The satellite that first carried ASTER, the EOS AM-I, is part of NASA's Earth Observing System (EOS). The ASTER instrument was subsequently launched in December 1999 aboard Terra to provide high spa- tial resolution instruments as one of five sensing sys- tems. See Earth Observing System. See the NASA ASTER Web site for information on ASTER's progress. http://asterweb.jpl.nasa.gov/ astigmatismAn aberration associated with lenses in which irregularities in the shape or general curvature of the lens cause more than one line of focus or in which a portion of the preferred line of focus is blurred. Astigmatism is inherent in a number of laser beam- generating technologies such as laser diodes. Since the semiconductor-based emission facet of a laser diode is typically rectangular, it causes an astigmatic beam (a beam with an elliptical cross-section) that is usually corrected with one or more lenses. ASTRAL Alliance for Strategic Token-Ring Ad- vancement and Leadership. A vendor-supported or- ganization formed in the mid-I990s to support mi- gration to High Speed Token-Ring LAN technology. The group prepared a number of white papers and a draft standard for 100 Mbps Token-Ring transmis- sions. With the emergence ofEthernet as a widely- adapted technology, interest in Token-Ring networks was waning in the late-1990s. See High Speed To- ken-Ring. Astro-D See Advanced Satellite for Cosmology and Astrophysics. Astrolink A commercial global satellite communi- cations service scheduled to come online in 2001. Astrolink International Limited is an independent Lockheed Martin venture. Lockheed Martin has been active in global communications frequency utiliza- tion conferences and on various ATM- and lTU-T- related technical and standardization committees and working groups. Astrolink is targeted at providing multimedia appli- cations over virtual private networks (VPN) with a focus on secure transmissions and connectivity be- tween private and public networks. The Astrolink system consists of nine geostationary satellites: five to provide global coverage, four to come online later. They will be operating over Ka- band frequencies with approximately 6-Gbps capac- ity per satellite using continuous beam uplinks and multi frequency TDMA. astronomical unit AU. A unit of length defined as the distance from the Earth to the Sun, a measure that is generally given as about 149,579,000 to 149,599,000 kilometers. The variation in the unit comes about due to the variation in the Earth's move- ment in relation to the Sun and the measuring sys- tem and criteria used to establish the distance. ASU application-specific unit. asymmetric 1. Not symmetric, lopsided, irregularly proportioned, unbalanced, one-directional, having one side larger or longer than the other. Asymmetric Digital SubscriberLine ADSL. A data communications service over traditional phone wires 71 © 2003 by CRC Press LLC . digital communications for aeronautics devices and facili- tated the development of modular, off-the-shelf prod- ucts. See ARINC-629. ARIN C-629 A commercial civilian communications protocol based upon a central twisted-pair bus archi- tecture which can accommodate up to 120 peripheral devices or terminals at a 2-MHz bus rate. ARINC- 629 evolved from ARINC-429 , which was developed in the 1970s. ARINC products are manufactured by Excalibur Systems, Inc. ARINC Incorporated. Notes ATS-I 1966 Spin-stabilized synchronous altitude. Electronically despun antenna. Stationed over the Pacific Ocean. Successfully photographed Earth and provided a presidential communications link for recovery of Apollo II. ATS-2 1967 Gravity gradient stabilized. Insufficient thrust resulted in an elliptical orbit and it lost orbit after only 88 0 days. ATS-3 1967 Synchronous orbit. Mechanical despun antenna, color camera that photographed tornados in 19 68 and an eclipse of the Sun in 1970. ATS-4 19 68 Gravity gradient stabilization in synchronous altitude. Failed to reach intended orbit and lost orbit in 19 68, two months after deployment. ATS-5 1969 Synchronous orbit. Gravity gradient booms for stabilization didn't deploy correctly, but some of the experiments were successful. It was retired in 1 984 . 63 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary well-known tradename Kevlar. See Kevlar, swelling tape. Aramid Yarn in Fiber Optic Cable In a typicalfiber optic cable assembly, the aramid yarn. artificial neuron. The familiar name for an electronically simulated neuron used in a maze-run- ning robotic mouse in the early 1960s. See Melpar model, neural network. 67 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary AS 1. See Applicability Statement. 2. See autono- mous system. as is Atenn applied to products that are bought and sold with no implied or stated warranties. Condition may be guessed by inspecting and trying the equip- ment, but there is no way to know the completeness, remaining useful life, or technical functionality of the equipment. See fair, good. AS&C 1. Advanced Systems & Concepts. A division of the U.S. Department of Defense associated with the Deputy Under Secretary of Defense (DUSD). ASCO, the DTRA Advanced Systems & Concepts Office, encourages seed projects for technologies developed to counter threats to national security. 2. Alann Surveillance and Control. AS-Interface, Actuator Sensor Interface, AS-i. An open network protocol for automating actuator and sensor control for industrial applications. It can op- erate as a controller or as a stand-alone automation support bus. It may also be used with higher level field buses to enable remote input/output operations. A single AS-i v2.0 master can support up to 124 ac- tuators/outputs and 124 sensors/inputs. See actuator, INTERBUS, PROFffiUS. ASA 1. See Acoustical Society of America. 2. Assis- tant Secretary of the Army. ASARS See Advanced Synthetic