Fiber Optics Illustrated Dictionary - Part 51 ppsx

Fiber Optics Illustrated Dictionary provide a forum for participation in the planning and administration of the General Services Admin- istration's long-distance telecommunications services provided through the FTS2000 program. Since then, it has become a focal point for the development and administration of federal technology programs. interapplication communications lAC. A transpar- ent means of intercommunication between computer software applications (e.g., between a word proces- sor and drawing program). A similar concept was dubbed Compound Data Architecture (CDA) by Digital Equipment Corporation (DEC). The concept is now frequently implemented in layered architec- tures on multitasking systems, but in the early 1990s, surprisingly, it was not prevalent on desktop systems. Once a user has experienced the ease of moving around data and images among different types of ap- plications or among applications from different ven- dors, it's hard to go back. INTERBUS An open systems frame-based, data bus interface device standard and protocol for high-per- formance, distributed networks for manufacturing and process control. INTERBUS standards enable devices from different manufacturers to exchange information through standardized profiles for robotic controllers, peripheral drives, data encoders, indus- trial valves, etc. It is a bit-oriented, synchronous pro- tocol that is used with sensors and actuators. INTERBUS is implemented on ring-based, token- passing networks and utilizes a single multipair cable to interconnect all devices, regardless of type or level of complexity. See actuator, PROFffiUS. IntercarrierInterface ICI. One of the two interface ports ofXA-SMDS systems which is used to specify how the carrier switch sends and receives data from an Interexchange Carrier's (IXC's) SMDS network. The other interface is the Subscriber Network Inter- face (SNI). See Exchange Access SMDS. Intercast An Intel term for technology that allows a consumer to interface the TV set with a computer hooked up to the Internet, to receive "push technol- ogy" Webcasts or Netcasts, that is, digital broadcasts of information and entertainment transmitted over the Web rather than through television broadcast air- waves or television cable services. The digital infor- mation from the Web is displayed in the blanking spaces of the TV signals, so the TV can still receive normal TV broadcasts in addition to displaying Intercasts. See Webcast. Intercept Service A service in which a call to a changed or disconnected number is routed to a record- ing or, ifa recording is not available, to an Intercept operator. In the case of the latter, the caller will be verbally asked for the destination number and the operator will attempt to complete the call. Interchange A commercial Internet connection ser- vice from Ziff-Davis, similar to some of the other large Internet Service provisions, but with a slightly more technological slant. Interchange Carrier IC. A common telecommuni- cations carrier that provides inter- or intra-LATA ser- vices through local public exchanges according to 492 definitions and regulatory guidelines established by the Federal Communications Commission (FCC) and the Telecommunications Act. See Inter Exchange Carrier. Interchange Format See Rich Text Format. intercom abbrev. intercommunication, inter- communicator. A set of at least two devices, mini- mally atransmitter (with a microphone) and receiver (with a speaker) or two transceivers, over which re- mote communication can take place in at least one direction. Most intercoms are audio only, but audio/ visual intercoms are becoming more prevalent as the technology becomes more readily available. Intercoms can generally be categorized as wired or wireless. Wired intercoms sometimes use existing wiring (e.g., doorbell wires in the walls of houses). Wireless intercoms use broadcast frequencies sent through the air or sometimes through building wir- ing using the AC sockets as an interface to the wir- ing for better transmission. Many wired and wireless intercom speakers are wall mounted, like the PAsystems in schools or hospitals, and the transmitter may be attached to a handheld mi- crophone or operated through a telephone handset. Baby monitors are a type of wireless mobile inter- com, in which one unit is placed near the baby and the other is placed near the parents or babysitter or attached to their clothing so they can move around. Intercoms are often incorporated into phone systems, so that the handset or speakerphone is the transmit- ter and the receiver is a speakerphone on another con- sole (or on several consoles in broadcast mode). The distinction between wireless intercoms and wire- less radios is not a hard and fast one; there is overlap in capabilities between sophisticated intercoms and simple radio systems; the main difference is in ease of use. Intercoms and basic two-way short-distance radios tend to be unlicensed push-button devices, whereas wireless radios tend to be licensed devices, some requiring a higher level of expertise to operate. In this sense, a computer videoconferencing system can be called an intercom system. Once the software application is installed and launched, the u~er need only sit in front ofa microphone and small camera in order to communicate with the person at the other end of the connection. No sophisticated skills are needed and even the push-button aspect of the com- munication has been eliminated. Since videoconferencing systems aren't subject to the same distance restrictions as low-power wireless de- vices, it's possible that small flat-screen monitors with built-in speakers will eventually replace traditional intercoms. Parents will be able to readily see what their kids are doing in daycare or at school. Friends can keep in touch without making long-distance calls. Business associates can discuss important projects or interact in meetings from home or a remote office (or from the road with a wireless modem). When high- speed communications become available to a major- ity of users, Internet intercoms may well become one of the most prevalent telecommunications technolo- gies. See public address system, videoconferencing. © 2003 by CRC Press LLC Interdepartment Radio Advisory Council IRAC. An assemblage ofcommittees, subcommittees, and working groups providing expertise and notification to the International Telecommunication Union (ITU) regarding the allocation and management of radio frequency spectra. IRAC develops procedures, pro- cesses requests, and assists in assigning frequencies to U.S. Government radio stations. IRAC includes the Frequency Assignment Subcommittee (PAS), the Spectrum Planning Subcommittee (SPS), the Tech- nical Subcommittee (TSC), the Radio Conference Subcommittee (RCS), and the International Notifi- cation Group. Interexchange Carrier Compatibility Forum ICCF. An organization that developed an expansion plan for telephony Carrier Identification Codes (CICs) when they became scarce in the late 1980s. The ICCF also served as a liaison in standardization efforts for fiber interconnectivity in the mid-1980s. interface n. A hardware connection, or logical con- nection or translation point between two or more de- vices or transmissions media. Interfaces are an intrin- sic part of interconnected computers, peripherals, and networks. Almost every aspect of data and electrical connections in the telecommunications industry uses a different format or version of a format, and the in- terface is the point at which all these different hard- ware and software junctions come together. Common electronic interfaces include docking bays, cradles, cable connectors, peripheral card connectors, card slots, and chip sockets. interface, human-machine n. The point ofcontact or translation between humans and machines. • A hardware interface is a device or system that translates human movement, speech, or sensory output into impulses (usually electromagnetic or mechanical, though chemical interfaces also ex- ist) that the machine or computer device can in- terpret and compute into data and instructions or, conversely, that translates machine signals into sensory output or information meaningful to hu- mans. Human-machine interfaces come in many vari- eties, including digital, analog, mechanical, chemical, or a mixture of these. Examples of hardware input interfaces include microphones, keyboards, joysticks, temperature sensors, serial connectors, video cams, data gloves, and pressure pads. Hardware output interfaces include moni- tors, speakers, pulsing lights, thermostat control- lers, infrared device controllers, and more. • A software interface is a system ofalgorithmic procedures/functions to meaningfully communi- cate information and options to humans and/or to interpret human communication and sensory into machine instructions. Common software interface conventions include the use of textual queries and responses, graphi- cal pointers, folders, menus, and other culturally meaningful icons that indicate the state of the de- vice, availability of services, current point in a process, etc. Human-machine interfaces evolve through a system oftrial-and-error combined with the sometimes id- iosyncratic preferences of the people who design the applications or market the devices to the general pub- lic. At the present time, software interfaces are often developed intuitively by computer programmers with little or no input from users even though they are in- tended to satisfy the needs ofa broad spectrum of people, rather than the more individual needs and preferences of the programmer, in order to produce products with commercial viability. Unfortunately, interfaces become entrenched even if they are no longer appropriate or practical. Early ver- sions ofatechnology are often designed to overcome pioneering design limitations. As the limitations are overcome, the increasingly inefficient interface may be retained because users have become accustomed to it or because it is expensive to change production lines. The QWERTY typewriter keyboard layout is a good example. It was designed for historic manual typewriters and laid out with the letters organized so they would slow down the typist to help prevent jam- ming that occurred with old-style mechanical keys. When electric typewriters and computer keyboards were developed without the jamming problems, the QWERTY layout was retained even though the origi- nal reason for the layout became irrelevant. The concept of the interface is an important one as it influences how comfortably and efficiently humans can utilize a technology. Ease of use and interface design are essential to the success and proliferation of many telecommunications products. Interface de- sign also reveals priorities; sometimes humans are expected to adapt to the limitations ofa technology rather than the technology being designed to serve the needs of humans. Interface Control Application Programming In- terface ICAPI. A telecommunications call control library that facilitates network interface access for T1 robbed-bit signaling systems or TIlE1 CAS. It fits between the operating device drivers and the appli- cation. There are similar call libraries for ISDN and ANAPI. An ICAPI protocol uses bit transitions and in-band signaling to establish calls and transmit call information. Events and channel states may be logged. Interface Data Unit IOU. In ATM networking, in- terface control information transferred to and from the upper layer in one interaction across the layer. A service data unit (SOU) may be passed across ATM Adaptation Layer 5 (AAL5) as an IOU correspond- ing to one protocol data unit (DPDU) in a one-to-one correspondence or, depending upon the type ofser- vice (e.g., message or streaming mode), the SDU may also be passed across AAL5 in more than one IDU. Interface Device In Frame Relay networks, the In- terface Device provides a link between an end device and the network through encapsulation. See encap- sulation, Frame Relay Capable Interface Device. interference Extraneous, unwanted signals that hinder transmission or perception of the desired sig- nal. Types ofinterference include noise, static, pops, 493 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary crackles, echo, babble, chatter, crosstalk, cosmic noise, and background noise. See individual entries in this dictionary for details. interference grating A grating created through a photoresist laser etching process by exploiting the in- teraction between the intersection of collimated light beams of the same wavelength. It is sometimes called a holographic grating due to the three-dimensional tapered effect between high and low points in the grat- ing. The sinusoidal cross-section makes it difficult to impose a blazed pattern on an interference grating, putting some limits on the efficiency of this type. In- terference gratings came into practical use in the late 1960s. They are favored over ruled gratings for a number of precision applications due to greatly re- duced incidence of stray light, particularly in grat- ings with fine grating periods (reduced distance between adjacent facets). Photographically etched Interferometer Examples Type Abbreviation Description Fabry-Perot FPI Fizeau FI Mach-Zehnder MZI 494 A high-resolution interferometer utilizing multiple reflections from two proximate reflective surfaces. A Fabry-Perot interferometer with Michelson-type mechanical motion was designed by the National Bureau of Standards (NBS) in the early 1900s to make the first precision measurements of wavelengths published by the NBS. In cooperation with the University ofPittsburgh, MIT uses this type of interferometer with a cooled gallium-arsenide photocathode photomultiplier as a detector, with a computer as a controller, for night sky observations. There are FPIs installed in the Antarctic, Norway, and many other locations to remotely sense upper atmosphere wind and temperature conditions. Doppler concepts are incorporated into the sensor readings for meteorological observations. Fabry-Perot filters have also been suggested by Wickham et al. for use as sub- band tuning mechanisms (in conjunction with Bragg reflection gratings) for optically channelizing radio frequency (RF) signals for spectral analysis ofthe very high frequencies now used for communications signals. Bragg reflection gratings and FP filters have further been described by Bao et al. as a mechanism for determining wavelengths oftransmitted or reflected light through a calibrated wavelength reference, thus creating a reference system. A basic type of image plane interferometer useful for noncontact testing of surface characteristics and for telescope design. The Fizeau interferometer produces a direct image from the source and does not incorporate the same degree of beam diversion characteristics as the other interferometers mentioned here. The FI is used in many astrophysical applications. More recent digital phase- shifting FIs have been developed by CSIRO for in-house precision metrology of optical components. A historic interferometer descended from the Twyman-Green interferometer. With improvements, the MZI is still common as a calibration and diagnostic instrument. It is most often used in aerodynamics, thermal transfer, and plasma physics, but is also being studied in fiber optics research. The MZI is favored for many educational applications, as a basic model can be built by students in a rectangular or parallelogram configuration. Depending upon the alignment of the reflecting surfaces, interference fringes mayor may not be produced and, by controlling the length of the optical path, phase shifts can be introduced in a controlled manner. The extent of the shift provides a means to monitor relative changes in the optical path, thus providing useful measurement information. The beam phasing characteristics of an MZI can also be modeled in computer software. The MZI is both simple and sophisticated, depending upon how it is implemented. It is not only a good student project, but also has been proposed for use as an atomic interferometer. MZIs are useful in the fabrication and testing ofcomponents and various sensors used in telecommunications. They have also been incorporated into integrated circuits for converting optical wavelengths and have been developed into directional coupler switches. cont. © 2003 by CRC Press LLC gratings are often easier to impose on nonplanar shapes than machined ruled gratings. On the other hand, they also tend to require higher intensity light sources than ruled gratings. By placing photoresistive material in an interfero- meter and controlling the angle at which a light beam hits and rebounds from a reflective surface, it is pos- sible to have a single light source etch astandingwave interference pattern, with the angle related to the dis- tance between grooves. If two planar beams of the same wavelength and intensity (at the point of inter- section) are aimed from slightly different directions onto a planar photoresistive surface, they will etch out a regularly spaced, grooved classical grating. Other types ofwaves and other imaging surfaces ex- ist, some of which are useful for compensating for the characteristics of other components, but the abovementioned are common in the fabrication of semiconductor gratings. See diffraction, grating, interferometer, photoresist, ruled grating. interference guard band See guard band. interferometer Because of its wavelike properties, a beam of coherent light can be split and realigned in such a way that factors that interfere with one of the beams can be detected when compared to an unim- peded reference beam or, more simply, the split beams can be compared to detect subtle changes to one or more of the beams. Thus, a device that detects and displays interference between two or more light wave trains and, optionally, compares wavelengths against reference displacements is called an interferometer. Because light technologies can be very precise, com- pared to mechanical devices, interferometers can be used for very fine detection and calibration. The in- terference pattern information derived from an inter- ferometer is useful in measurement or calibration, for example, to determine angular positions in satellite tracking. A series of horizontal or vertical measure- ments at precise distances along apath can yield data that can be processed to yieldplanar information (e.g., a height profile in an optical fiber). There are avariety of types of interferometers, rang- ing in complexity from simple lab-built student mod- els to more sophisticated instruments that incorpo- rate integrated circuit (IC) concepts. There are also different modes for which an interferometer can be designed. The optical path length of a test and refer- ence beam can be changed in their relationship in a series of phase shifts. In an optical fiber, the result is a lateral shift in the interferometric fringe pattern to measure the dimensions of a surface. Another ap- proach is to scan down through a fiber to produce an interference signal along a series of points on a sur- face. With digital processing, the data can be as- sembled to generate a surface height profile. Interferometers have been proposed as instruments to determine electrical states in silicon-based inte- grated circuits (ICs) and as diagnostic instruments for optical computer networks. One interesting applica- tion is the light-in-flight speckle interferometer Interferometer Examples, cont. Type Abbreviation Description Michelson MI A basic interferometer developed by A.A. Michelson to conduct the Michelson- Morley experiment in the 1880s. The scientists used the interferometer to determine whether a theoretical medium called the aether existed and could be detected. Michelson received a Nobel Prize in 1907 for his discoveries in optical science. In a Michelson interferometer, a monochromatic point light beam is split in two by a partially reflective material, such that one beam continues in the original direction, and the other is reflected (usually 90°) from the original course. The beams are recombined with the resulting interference patterns displayed on a screen. These are derived from the wavelike characteristics of light and can be analyzed to determine vibrational or thermal effects, which are useful in fabrication and diagnostics. The image in a Michelson interferometer is not viewed directly as in a Fizeau interferometer but, in viewing instruments such as telescopes, can be reconstructed. By calibrating the MI with a known reference, the wavelengths ofother unknown materials (e.g., gases around astronomical bodies) can be studied through known interference characteristics. MIs are also used to develop standards in atomic lengths. Twyman-Green TGI A basic type of interferometer used as an optical fabrication and diagnostic tool, developed by Frank Twyman and Arthur Green in the early 1900s. The modem TGI is based upon a monochromatic point light source at the focal point ofa lens. By revealing patterns of optical interference resulting from unequal light paths, the TG I can be used to assess optical surface characteristics such as the flatness of a surface, performance ofa component (e.g., aprism), or deviation from a reference shape. 495 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary presented by Swedish engineers for evaluating 3D shapes by using ultrashort laser light pulses. On a software level, algorithms for phase-stepping in- terferometry have been developed by Chinese sci- entists. Interferometers are important in many aspects of as- tronomy. Not only are telescopes based upon inter- ferometric principles, but Fizeau interferometers (FIs) are included as payloads on space missions, selected for their accuracy and capability of sensing over a wide field The Global Astrometric Interferometer for Astrophysics (GAIA) mission, for example, includes three stacked, mechanically connected FIs designed to observe about 50 million stars. Historic interferometers were based upon noncoher- ent, mixed-wavelength light, while interferometers developed since the invention of lasers typically use coherent, nearly monochromatic light. The Interfer- ometer Examples chart includes a short list of some common, representative interferometers used in re- mote sensing, and component fabrication and testing applications relevant to telecommunications. Interferometers may be further optimized for a par- ticular task such as assessing the cleave ( terminal cut) of an optical fiber by forming an interference pattern between the fiber surface and an optical reference. A CCTV camera or other display device may be used to enlarge and display the cleave so the angle and evenness of the cut can be seen. A divergence of angle can be counted as a specific number of fringes in a fiber ofa specified diameter. The shape of the fringe pattern can indicate the evenness of the surface. The inteferometer may be customized to be self-calibrat- ing for this task and accurate within a tolerance of one fringe, enabling a cut to be accepted or rejected (and possibly recut), before connecting to other com- ponents. Some interferometers can interpret the vi- sual information into digital data for further process- ing, thus enabling lists or graphs of component char- acteristics such as angle of cut, smoothness, radius of curvature, etc., to be generated. See beam splitter, cleave, coherent light, ferrule, spectrometer. interferogram A visual measurement diagram de- rived from.output from an interferometer. A series of interferograms may be digitally processed to gener- ate a surface height profile of the medium observed (e.g., optical fiber) See interferometer. Interim Local Management Interface ILMI. A means of providing an ATM device with status and configuration information about virtual connections, and the registered ATM prefixes, addresses, services, and capabilities available at its ATM Interfaces through the Simple Network Management Protocol (SNMP) and an ATM Interface Management Infor- mation Base (Mill). ILMI is an open protocol that was developed as an interim solution by the ATM Forum in the mid-1990s to enable the exchange of UNI management information through direct encap- sulation over ATM adaptation layer 5 (AAL5). How- ever, the interim designation was dropped. ILMI is not universally implemented and meta-signaling may be used to serve this purpose on some systems. 496 Interim Number Portability INP. The use ofvari- ous telephone subscriber services, such as call for- warding, call routing, and call addressing, to allow a call to be redirected to another location, usually on a temporary basis. interior In ATM networking, an item such as a link, address, or node inside a PNNI routing domain. InteriorGateway Protocol IGP. A family of network routing protocols for exchanging information with other routers and switches on the same system. When changes occur in the organization of the network, these changes are communicated to the routers, so the routing table databases may be revised accordingly. InteriorGateway Routing Protocol IGRP. A Cisco Systems proprietary multipath routing protocol de- veloped in the mid-1980s for routing within autono- mous systems. Since then, the protocol has been fur- ther developed and many users have replaced Rout- ing Information Protocol (RIP) with IGRP to run on large, heterogenous networks, like the Internet. IGRP was intended to run in a variety of network environ- ments and enhanced IGRP has been developed to sup- port TCP/IP, IPX, and AppleTalk. IGRP-enabled routers send some or all of their rout- ing tables to neighboring routers at regular intervals, a process that also enables distances among nodes to be calculated as the information propagates out through the network. interlace A system used in frame-based video image display to display images in two-frame passes, with one pass imaging the odd lines and the next the even lines (or vice-versa), in an alternating pattern. Thus, in NTSC, for example, an interlaced screen is imaged in two fields of262.5 lines (to make up the full 525 scan lines), each field taking 1/60 ofa second. Some flicker can be seen on an interlaced display, so non- interlaced monitors, including multi sync monitors, have become prevalent on computer systems. Gen- erally, the faster the refresh, the more stable the im- age. See cathode-ray tube, field, frame, interleave, multisync, scan, scanning rate. interleave v. t. 1. To arrange in alternating layers, rows/columns, or time slices. 2. In concurrent pro- gramming, a logical means to execute sequences in order to analyze the correctness of concurrent pro- grams. 3. In networking, to transmit pulses through a single path through time-division from more than one source. 4. In graphics file storage and display, a means of arranging the image data so that all odd lines of the image and all even lines of the image are stored or displayed as a group. 5. In magnetic and magneto- optical data storage, a means and pattern of storing information on a disk so that the physical character- istics of the read/write sequence are accommodated without the drive head needing to "backtrack" to find the next section of data. 6. In multimedia applications, a means of slicing up the recording space so that dif- ferent media (sound, graphics, etc.) are laid down in strips or sections on the tape or disc. 7. A data trans- mission error-correcting technique in which code symbols are arranged in an interleaved pattern before transmission and reassembled upon receipt. © 2003 by CRC Press LLC interleaved ,rideo A video display in which a frame is constructed and displayed by alternately scanning all even lines and then all odd lines. This system of display is commonly seen on televisions screens and on some NTSC-compatible computer screens. A cer- tain amount offlicker is usually noticeable on inter- leaved displays. See interlace. interleaver In fiber optics systems, a multiplexing component that can increase channel density. Filters may be used to receive channels or route channel groups. See add/drop multiplexer. intermediate frequency IF. In heterodyne receivers, the beat frequency created as a result of the differ- ence between a locally generated signal and the in- coming radio signal. See beat frequency. Intermediate Signaling NetworkIdentification In Signaling System 7 (SS7), acapability that allows an application process in the originating network to specify intermediate signaling networks for noncircuit-associated signaling messages, and/or to notify an application process in the destination net- work about intermediate signaling networks. intermittent errors Fault conditions that happen occasionally, sometimes without apparent pattern, or occur from specific causes that happen seldom or ir- regularly. Difficult to anticipate and diagnose, inter- mittent problems are often not alleviated until a pro- gram has been run hundreds of times or a computer or phone network has negotiated thousands of calls. intermodulation distortion A type of audio distor- tion that occurs when multiple tones interfere with one another in a way that is not harmonically related to the original tones. internal modemAcomputer modem installed inside a larger system that is utilizing the modem. Internal modems are usually powered by the system in which they are housed and usually take the form of small PC boards or very small PCMCIA cards. Sometimes referred to tongue-in-cheek as "infernal modems," in- ternal modems can be finicky to install in systems with several peripherals that require IRQs. Internal modems are convenient in that they are out ofsight and mind, and don't take up extra space - a real plus on laptop computers. They have disadvan- tages as well, as they are often machine- or platform- specific and often can't be reinstalled in a new com- puter of a different type, as can most external mo- dems. External modems are easier to swap among systems, can be shared by a number of users through a switcher, and usually have status lights that are handy diagnostic tools. Since most internal modems install in a slot that faces the back of the system, they often don't provide status lights. In general, people prefer internal modems on small mobile devices and external modems on desktop systems or systems with shared resources. InternationalAd Hoc Committee IAHC. See Inter- net International Ad Hoc Committee. International Alphabet No.2 An older alphabetic coding system ofequal-duration pulses ofnegative and positive volts (called marks and spaces) in groups of five, to represent character signals. The beginning and end ofeach character was signaled by a start sig- nal and a stop signal. The use of five elements in two possible polarities results in 2 5 or 32 character en- codings. Even for a basic alphabet, this was some- what limited, and schemes to double the number by allowing a code to represent one of two characters were devised. Something similar happened later with computer character codes. International Alphabets evolved into ASCII and became widely implemented on comput- ers, but there were only 128 characters, insufficient for accents or math symbols. Many developers added 128 codes for a total of 256 characters and called it "extended ASCII." Technically, the extra codes weren't standard ASCII and were not consistent across platforms. Another limitation was that they couldn't be used together, the user had to select ASCII or "extended ASCII" banks. In the mid-1980s, the Amiga and Mac removed this limitation, enabling individual addressing of letters in both. See Appen- dix for an ASCII chart. See ASCII, Unicode. InternationalAmateurRadio Union lARD. A regu- latory agency and proponent ofworld amateur radio activity established in France in 1925. Amateur ra- dio organizations throughout the world interact with a high degree of cooperation and communications. The IARU is essentially to global amateur radio com- munications what the American Relay Radio League (ARRL) is to American amateur radio. The IARU is organized into three regional organizations that par- allel administrative divisions of the International Telecommunication Union (ITU). See American Ra- dio Relay League. http://www.iaru.org/ International Atomic Time, Temps Atomique In- ternational TIA. An atomic time scale based on the coordinated efforts of more than 200 atomic clocks from more than 50 centers from around the world, which are maintained in France by the Bureau Inter- national des Pods et Mesures. Unlike the Coordinated Universal Time (UTC), which is adjusted occasion- ally in leap seconds to maintain some coordination with the Earth's axis rotation, TIA is not adjusted, but remains consistent with atomic time scales. Other- wise, TIA and UTC are very similar. See atomic clock, Coordinated Universal Time. International Business Machines ffiM. In the late 1800s, Herman Hollerith, an American engineer, evolved the concept ofpunched cards as a storage medium and applied it to the development ofa tabu- lating machine, an early computer that could be used to store and process information in categories. This resulted in Hollerith cards, Hollerith code, and a ma- chine which could tabulate the vast amount of cen- sus data gathered at regular intervals in the United States. The tabulating machine dramatically im- proved the efficiency of storing and analyzing cen- sus data, and Hollerith formed a company called the Tabulating Machine Company. This later merged with several other companies to form the Computer- Tabu- lating-Recording Company, which sold a wide range of industrial products. Thomas 1. Watson, Sr. left NCR to join the company 497 . ' • : • :: • :: •. :.': .• :: .• : )i:J(:: : ~j © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary as general manager in 1914, and remained with the company for over four decades, eventually passing on the position to his son, Thomas J. Watson, Jr. On Valentine's Day, in 1924, the name of the company changed to International Business Machines Corpo- ration. IBM became an enormously influential com- pany in the business and computing market, and funded or partially funded the research and develop- ment of several historic room-sized computing ma- chines. IBM's research laboratory has contributed a great legacy oforiginal and fundamental scientific discoveries of interest both inside and outside the computing industry. IBM inventions are awarded more than 1000 patents per year; in other words, IBM develops as many unique inventions in a single year as the best individual inventors of the 1800s devel- oped in their entire lifetimes. In 1975, IBM released its first microcomputer, the IBM 5100; it was not a commercial success, and it was not until 5 years later that the first of the long IBM PC line was introduced to the public. This time sales were good, particularly in the business market, and IBM and IBM-licensed personal computer tech- nology became the most common platform for desk- top computing. See Hollerith, Herman; IBM Personal Computer, Jacquard loom. International Center for Technology Assessment ICTA. A nonprofit, bipartisan organization dedicated to helping government officials and the public in un- derstanding technology and how it affects human society and the environment. ICTAexplores and com- municates the social, economic, ethical, political, and environmental impacts related to the manufacture, distribution, and application of technologies. ICTA also uses legal petitions, comments, and litigation to fight against harmful deployment of technology. http://www.icta.org/ International Commission on Technology and Ac- cessibility ICTA. A commission to explore develop- ments in technology that may assist people with dis- abilities and to promote and disseminate their under- standing and use. ICTA was founded in the 1960s in Sweden in conjunction with Rehabilitation Interna- tional (RI) and the Swedish Handicapped Institute. In 1969 ICTA and RI developed and adopted the In- ternational Symbol of Access (ISA). http://www.ictaglobal.org/ International Commission for Optics ICO. An in- ternational organization affiliated with the Interna- tional Union of Pure and Applied Physics the sup- ports and promotes the dissemination of knowledge in optics, founded in 1947. http://ico-optics.org/ International Correspondence Chess Federation ICCF. This is one of the more interesting historic bod- ies using telecommunications to enhance gaming communications. The ICCF has evolved from the lnternationa/er Fernschachbund, founded in 1928, which was succeeded by the International Correspon- dence Chess Association, in 1945, to become the ICCF in 1951. Correspondence chess hasn't only been conducted through postal mail services. ICCF members and chess players in general have always 498 been technology conscious and have enjoyed their matches through the use of homing pigeons, tele- grams, trains, planes, computer modems, and high- speed connections to the Internet. International Data Encryption Algorithm IDEA. A European-designed, 128-bit, single-key encryption algorithm used for data security. It has been incorpo- rated into Pretty Good Privacy (pGP) partly because it doesn't have the same U.S. export restrictions as other encryption algorithms. Use of IDEA is license- free for noncommercial use. See encryption, Pretty Good Privacy. International Development Markup Language IDML. An Internet protocol and associated set of standards to facilitate development in a global con- text. In 1998, the Development Markup Language (DML) was seen as a means to support the markup of information on computer networks that describe developmental activities and mandatory data ele- ments described by relevant standards. It was in- tended to be consistent with other meta data schemes and capable of multilingual markup. In February 1999, DML was renamed IDML. The IDML Work- ing Group was formed to develop recommendations and a process for electing an IDMLAdvisory Group. It is recommended that XML be used for Site Descrip- tion files even though other formats may be used. Extended IDML is a superset of the Core Activity Schema with additional audit trail and informational items. IDML was established as a pilot standards- track candidate in early 200 I. See Extensible Markup Language, IDML Initiative. International Electrotecbnical Commission IEC. An international standards-development and recom- mending body, founded in 1906 as a result ofa 1904 resolution at the Electrical Congress. The IEC pub- lishes standards for electrical, electronic, magnetic, and related technologies and promotes cooperation among member countries. IEC standards form the core of the World Trade Organization's Agreement on Technical Barriers to Trade (TBT). Hundreds of technical committees and working groups carry out the mission of the IEC. Technical committee papers are submitted to a full-member National Committee members' vote in preparation for approval as inter- national standards. http://www.iec.ch/ International Engineering Consortium lEe. A nonprofit professional organization supporting engi- neering research and education sponsored by univer- sities and engineering societies, founded in 1944. The focus of the organization has broadened from a na- tional to international purview and from electronics to information engineering. IEC sponsors courses, conferences, virtual exhibits, and a number ofpubli- cations. http://www. iec.org/ International Federation for Information Process- ing IFIP. A nonprofit, nongovernmental, information processing research organization. IFIP was estab- lished in 1960 under the auspices of UNESCO after the first World Computer Congress of 1959. A num- ber of technical committees provide expertise on tech- nological matters. http://www.ifip.or.at/ © 2003 by CRC Press LLC InternationalForum on the White Paper IFWP. An international series of workshops, founded in June 1998, intended to bring together professionals and experts in law to respond to White Paper recommen- dations for assigned numbers on the Internet. The process of open discussion and the goal of self- regulation were key aspects of these proceedings. The Internet community believed that it was possible for those in the industry to produce a viable system for assigning Internet addresses without government takeover of the process and used the Internet itself as an important venue for meetings, opinions, and some- times heated debates over how addresses would be allocated and assigned. As a result of initial discussions, a California non- profit public benefit corporation called the Internet Corporation for Assigned Names and Numbers (ICANN) was tendered as a draft recommendation as a means to coordinate the administration of Inter- net domain names and Internet Protocol (IP) ad- dresses. The draft proposal, jointly presented by Net- work Solutions, Inc. and the Internet Assigned Num- bers Authority (lANA), was discussed in September 1998 by IFWP with regard to how it fell within a model of common principles and structure specified by the u.s. Department of Commerce Statement of Policy on the Management of Internet Names and Addresses. Three proposals were presented to the Deptartment of Commerce in October 1998 by dif- ferent groups, and testimony was presented on trans- ferring the Domain Name System to the private sec- tor. ICANN's bylaws and its first public meeting were held in November 1998. See Intemet Assigned Num- bers Authority, Internet Corporation for Assigned Names and Numbers, InterNIC. International FrequencyRegulation Board IFRB. An agency established by the International Telegraph Union in 1868 to manage the broadcast frequency spectrum. In 1912, the IFRB's Table of Frequency Al- locations became mandatory. The frequency alloca- tion table specified frequency bands for specific uses in order to minimize interference among stations. See Federal Communications Commission, International Telegraph Union. InternationalInformation Systems Security Cer- tification Consortium ISC2. A nonprofit corporation established in 1989 to develop certification programs for security professionals working in the informations services field. http://www.isc2.org/ International Intellectual Capital Codes Associa- tion IICCA. Anot-for-profit association tasked with defining a comprehensive lexicon of skills of inter- est to industries and users for employment/employee matching through the iCAP Catalog and the Intellec- tual Capital Inventory (iCAP) system. IICCA is re- sponsible for the development, maintenance, and uniformity of the iCAP Catalog. See iCAP. International Internet Association A fee-based In- ternet service that provides access to more than 20,000 databases from around the world. InternationalInternetIndustrialAssociation lIlA. A professional association of Internet Service Provid- ers (ISPs), Web developers, software developers and others directly influencing or being influenced by the development of the Internet. The IlIA is concerned with issues such as the addition of a larger available base of international Top Level Domains (TLDs). http://www.iiia.org/ http://www.iatld.org/ InternationalMobile SubscriberIdentity IMSI. An lTU- T identification number assigned by a wireless carrier to a mobile station to uniquely identify the sta- tion locally and internationally. InternationalNetworkforDevelopmentInforma- tion Exchange INDIX. Acoalition for organizations involved in development in information exchange. INDIX developed the CEFDA standards for data ex- change and participated in the development of the International Development Markup Language (IDML). See IDMLlnitiative. http://www.indix.org/ International Organization for Standardization (International Standards Organization) ISO. An important international standards-setting body which has produced many of the specifications and docu- ments used by telecommunications professionals. ISO is familiar to many through its ISO-9000 series of quality assurance specifications. ISO-9000 stan- dards can be summarized as "Say what you do, then do what you say, and get it certified, if necessary." http://www.iso.ch/ International Radio Consultative Committee CCIR. A standards and regulatory-recommending body founded in 1927, descending from the Interna- tional Radiotelegraph Conference in 1906, in connec- tion with the International Telegraph Union. This or- ganization was formed in response to public broad- casts over radio waves in the early 1920s. See Inter- national Telecommunication Union (ITU-R). InternationalRadiotelegraphic Convention One of the early international gatherings, resulting from the growth of telegraphy, resulted in a multinational con- sent agreement regarding Protocol and Service Regu- lations that was documented in November 1906. The convention was to be entered into force in July 1908 by Great Britain, Germany, Austria, Hungary, Den- mark, and a number ofother European nations, Ja- pan, Argentine Republic, Brazil, Chili, Uruguay, Rus- sia, Turkey, Persia (now Iran), the U.S., and Mexico. The convention defined various types of telegraphic establishments common at the time, including coast and ship stations, and delineated operating parameters to ensure cooperation in the use of telegraphic trans- missions and designated frequencies, responses to distress signals, telegraphic charges, and other tele- graphic matters of international importance. See Ra- dio Communication Laws of the United States. International Society for Measurementand Con- trol ISMC. Formerly the Instrumentation Society of America (ISA), ISMC is a nonprofit professional or- ganization supporting manufacturers and engineers involved in the theory, design, manufacture, and use of measurement and control instruments and com- puter systems. See Instrumentation, Systems, and Automation Society. http:/www.isa.org http://www.isaca.com/ 499 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary International Special Committee on Radio Inter- ference CISPR. An international committee with members from a broad spectrum of the radio com- munications/engineering industry who work to pro- mote international agreement on aspects of radio in- terference to facilitate international trade. CISPR is composed ofa number of international organizations plus each National Committee of the International Electrotechnical Commission (IEC). Through conferences and subcommittees, CISPR promotes and produces information guidelines, sta- tistical methods, and standards related to the protec- tion of radio reception from interference from con- sumer goods and industrial equipment, electrical sup- ply systems, and broadcasting equipment. CISPR es- tablishes limits and requirements for immunity to in- terference and takes into consideration safety regu- lations as they affect interference suppression of elec- trical equipment. Of particular interest to telecommu- nications are CISPR publications on electromagnetic compatibility (EMC) and emission standards. http://www.iec.ch/ InternationalSpeech CommunicationAssociation ISCA. A nonprofit organization promoting interna- tional speech communication, science, and technol- ogy originally founded in 1988 as the European Speech Communication Association, ISCA was es- tablished in 1999. It is now an independent, self-sup- porting organization. ISCA's interests include re- search in synthetic speech development and process- ing. http://www.isca-speech.org/ International Switching Center ISC. A gateway exchange whose function is to switch telecommuni- cations traffic between national and international countries. International Telecommunication Regulations ITR. A set of international regulations intended to supplement the International Telecommunication Convention while also recognizing the individual rights of nations to regulate their telecommunications sectors. The ITR framework seeks to promote the efficiency, harmony, and evolution of global telecom- munications through established general principles for international telecommunication transport media and services offered to the public. Draft proposals of the ITR were presented at the world Administrative Telegraph and Telephone Conference in Melbourne, Australia, in 1988 per a resolution of the Plenipoten- tiary Conference of the International Telecommuni- cation Union (ITU). International Telecommunication Union ITU. A significant, influential, global United Nations stan- dards agency descended from the International Tele- graph Union. The lTU, headquartered in Geneva, Switzerland, provides extensive publications, pro- motes communication, sponsors international meet- ings and conferences, disseminates news, and devel- ops standards and regulations. The lTU oversees a number of subgroups, called sectors (see chart). The lTU is involved in a number of important com- munications venues for discussion and the dissemi- nation of findings. Examples include: 500 • The publication of the lTU Operational Bul- letin every 2 weeks to report on the adminis- trative and operational information exchanged among administrators, service providers, and recognized operating agencies (ROAs); coun- try codes and other statistical indicators are published in conjunction with the bulletin as annexes. • The organization of the World Radio- communication Conference (WRC) to admin- ister international agreements in wireless tele- communications technologies. • The organization of the World Telecommuni- cations Standardization Assembly to deter- mine needs and priorities related to standards development and dissemination. The convening of a Plenipotentiary Confer- ence every 4 years (1998, 2002, etc.), an im- portant meeting ground for member states where decisions on direction and policy are made and previous actions reviewed and de- bated. The 1998 conference was characterized by calls for greater involvement of the private sector in lTU activities. When the council is not convened, administration and oversight of the lTU is handled by the lTU Council. See Telecommunication Standardization Bureau. For abrief description oflTU-T history, see International Telegraph Union. For series lists and individual rec- ommendations, see Appendix C and alphabetized lists under letter designations. http://www.itu.int/ International Telegraph Union lTU. An old and influential organizing and standards-recommending body formed in 1865 when the telecommunications industry was beginning to boom. The lTU was cre- ated in response to the need for cooperation and for- mal agreements related to the installation and use of multinational telegraph systems. Twenty participat- ing countries signed the first International Telegraph Convention. After the invention of the telephone, the Telegraph Union drew up recommendations for legislation gov- erning international telephony. Radio communica- tions began to develop, so the Telegraph Union con- vened a preliminary radio conference in 1903 lead- ing to the Radio Regulations and founding of the In- ternational Radio Consultative Committee (CCIR). In 1934, the name was broadened to International Telecommunication Union. It became an agency of the United Nations in October 1947, and the head- quarters was transferred from Berne to Geneva in 1948. The Union later became known as the CCITT, as there were a number of cels set up for different areas of communication in the 1920s; the CCIT and the CCIF were amalgamated in 1956. In 1992, an important conference took place in which the organization was evaluated with the aitp of up- dating it to align with the complex, changing envi- ronment of current and future technologies. The or- ganization has recently been renamed International Telecommunication Union (ITU) because the funda- © 2003 by CRC Press LLC International Traffic in Arms Regulations ITAR. Rules issued by the U.S. State Department, under the authority of the Arms Export Control Act, to control the export/import ofdefense-related articles and ser- vices, including information security systems such as cryptographic systems and TEMPEST suppression technology. International World Wide Web Conference Committee See World Wide Web Conference Committee. ITV-D Telecom. Development Sector Facilitates global telecommunication development by providing organizing and coordinating expertise and assistance. The lTV -D works through conferences, study groups, the Telecommunication Development Advisory Group, and the Telecommunication Development Bureau (BDT). mental objectives of the original organization remain essentially the same today as they were over 100 years ago, and the convergence of the many media and communications technologies through digital trans- mission has united many formerly separate areas. (Source:elTU-TWeb site history.) In Canada, communication with the lTD is accom- plished through the Canadian National Organization for the lTV (CNO/ITD- T) and the Steering Commit- tee on Telecommunications of the CSA (CSA/SCOT). See International Telecommunication Union; Morse, SamueIB.F. ITV-R Radiocommunication Sector Descended from the International Radio .Consultative Committee (CCIR), this is the arm of the lTV responsible for researching technical and related regulatory issues. It regulates ground- and space-based radio frequency telecommunications. ITV-T Telecom. Standardization Sector Founded in March 1993, ITV- T replaces the International Telegraph and Telephone Consultative Committee (CeITT). The ITV- T endeavors to ensure efficient and on-time production of high quality standards covering all fields of telecommunications with the exception of radio, which is handled by ITV-R. The work of the ITV-T is handled by numerous study groups and is documented in tens of thousands of papers. Presently more than 2500 standards recommendations are in force that form a framework for global communications. internet When spelled with a lowercase "i," generi- cally refers to an interconnection of two or more data networks. While individual networks may be con- nected in any number of ways, it is common to inter- connect them through the Open Systems Interconnect (OSI) model as it ensures a good level of compatibil- ity with existing technologies and supports interoper- ability among a variety of types of systems. See In- ternet. Internet A global communications community of more than 60,000 cooperating networks, evolving in the early 1980s out of ARPANET, now known as the Internet or colloquially as the Net. The Internet consists ofa distributed network of tens of millions of computers linked together through small and large communications services providers. By early 1995, the Internet had more than 4 million hosts and the term was officially defined by the Fed- eral Networking Council. The Net is defined in the Telecommunications Act of 1996 and published by the Federal Communications Commission (FCC) as I " the international computer network of both Federal and non-Federal interoperable packet switched data networks." The evolution of the Net has been influenced by a broad base of technical and lay interests and an equally wide range of commercial and public inter- ests. The vocal promoters of the Net as a universal access communications medium to serve the public good have been joined by commercial interests seek- ing a way to use the Net to further private and public business interests. In the early days, the Net had a high proportion of users in technical and scientific fields and focused on cooperative communication and re- search. Since the mid-l 990s, an overwhelming influx of commercial vendors has changed the character of the Net, but there has also been a large growth in co- operative nonprofit and community organizations. In 1993, the United Nations and the U.S. White House came online, thus changing the ways to access and think about politics. Global doors have opened up to people doing genealogical studies and people are re- discovering friends they haven't seen since elemen- tary school. The phone network is undergoing sub- stantial changes due to competition from long-dis- tance email and chat resources that are available on the Internet without long-distance phone costs. The impact of the Internet on communications ven- ues and global culture is highly significant and will likely exceed the changes brought about by the in- dustrial revolution. The information glut and impact on personal privacy will be far-reaching as well. Speculations about the emergence of the Net as a fonn of digital intelligence may not be farfetched, and, with the cooperative communication possible among sci- entists and interested lay persons, research will move forward at an unprecedented rate. See ARPANET, Telecommunications Act of 1996, RFC 1958. Internet 2Aconsortium of more than 100 academic and nonacademic organizations working to develop a vision and implementation plan for the next Sector Notes ITU-T Subgroups (Sectors) Abbrev. 501 © 2003 by CRC Press LLC . Fiber Optics Illustrated Dictionary provide a forum for participation in the planning and administration of the General Services Admin- istration's long-distance telecommunications services provided through the FTS2000 program. Since then, it has become a focal point for the development and administration of federal technology programs. interapplication. LLC Fiber Optics Illustrated Dictionary presented by Swedish engineers for evaluating 3D shapes by using ultrashort laser light pulses. On a software level, algorithms for phase-stepping in- terferometry have been. user has experienced the ease of moving around data and images among different types of ap- plications or among applications from different ven- dors, it's hard to go back. INTERBUS An open systems frame-based, data bus interface device standard and protocol for high-per- formance, distributed networks for manufacturing and process control. INTERBUS standards enable devices from different manufacturers to exchange information through standardized profiles for robotic controllers, peripheral drives, data encoders, indus- trial valves, etc. It is a bit-oriented, synchronous pro- tocol that is used with sensors and actuators. INTERBUS is implemented on ring-based, token- passing networks and utilizes a single multipair cable to interconnect all devices, regardless of type or level of complexity. See actuator, PROFffiUS. IntercarrierInterface ICI. One of the two interface ports ofXA-SMDS systems which is used to specify how the carrier switch sends and receives data from an Interexchange Carrier's