Fiber Optics Illustrated Dictionary commonly used with audio/visual recordings that will later be edited, dubbed, or otherwise manipulated or played within strict time constraints. Time code is typically stored as hours, minutes, seconds, and frames. Time code was developed in the late 1960s when ana- log recording tapes became prevalent, in many cases replacing film. The system was developed because video tape lacked the sprockets which previously had been used on film to synchronize sound and images. In the 1990s, another transition was made from ana- log video tapes to digital recording technologies, and the time code techniques used for analog video and audio encountered certain problems when applied to digital recording technologies. See chase trigger, MIDI time code, reference clock, SMPTE time code. Time Division Multiple Access TDMA. A digital technology designed to overcome some limitations of analog cellular mobile communications. Time slot assignments allow several calls to occupy one band- width, thus increasing capacity for various wireless technologies. E- TDMA (Extended TDMA) provides even more time slots. TDMA is widely supported by AT &T Wireless Services. It is similar to Code Divi- sion Multiple Access (CDMA). See Demand As- signed Multiple Access. There are a number ofTDMA implementations, with three primary ones: European TDMA (GSM), Japa- nese TDMA (PHS/PDC), and North American TDMA (18-136). See AMPS, DAMPS, cellular phone, time division multiplexing. time division multiplexing TDM. A technique for combining a number of signals into a single signal by allocating a time slot in the combined signal with a multiplexer. At the receiving end, a demultiplexer is used to separate the interleaved signal back into its original signals. Some of the early developments of this technique were accomplished by J.M.E. Baudot in the 1870s. In current usage, TDM allows a variety of types of communications, audio and video, to be transmitted at the same time in one in- terleaved signal. time signals From around the mid-1800s before time zones were established, to the present day, people have sought to devise ways to determine the time and synchronize their activities. The first time signals were drums or bells that were regularly sounded in local communities based upon the sun's position. Later, in the 1860s, the U.S. Naval Observatory used the telegraph to transmit time signals, and soon West- ern Union was sending standard time signals, a tra- dition they continued for a century. Telegraph time signals were similar to current Coordinated Univer- sal Time signals, in that audible clicks were used com- ing up to the hour, just as tones now signal the up- coming minute. See Coordinated Universal Time, Greenwich Mean Time. Time T An lTU- T designation for 2359 hours Coor- dinated Universal Time (UTC) on 31 December 1996. time-delay modulation In optics, a form of phase modulation signal encoding the involves modulating a signal in the luminance channel with delays between pulses as the "carrier" signal. 932 time-space processing Also called temporo-spatio processing, this type ofprocessing is used in appli- cations and devices such as infrared motion detec- tors or radar systems which are using time and space as interrelated factors in their decision-making in terms ofprocessing data or signaling an alarm con- dition. Time-space processing is also used in adap- tive beam-forming antenna mechanisms. time-to-digital converter TDC. An instrument for sampling a short time interval between two electri- cal signals, usually in pico- or nanosecond resolu- tions. TDCs are useful for measuring the leading edge of the time interval between transmitting and receiv- ing pulses for tuning, maintaining, and troubleshoot- ing electrical systems. They may also be used for detectors, imaging systems, laser rangefinders, and time-of-flight measurements. In clock correction sys- tems, a TDC may be installed between a local clock and a processing system that derives optical data from theTDC. There are tradeoffs in timing resolution and linearity between digital and analog interpolation methods used with TDC data. Commercial TDCs typically include LEDs for dis- playing status and may support multiple independent channels (usually 4, 8, or 16). For longer time inter- vals, a counter and oscillator may be used. timing Configuration ofa system so successive rep- etitions are controlled for the desired interval (which may be desired to be variable), or so certain events begin and! or end at designated times or according to certain events. Timing is important in magnetic stor- age mechanisms, motors, signal amplitude sequences in electronics, and broadcast equipment configura- tions. Timing is also important on networks, where, for example, video and audio signals may be sent separately or on separate lines, but have to be coor- dinated at the end to provide services like videocon- ferencing. Constant oscillators are often used in con- junction with very precise timing devices. See atomic clock, quartz, SMPTE time code. timing signal 1. A signal generated according to an accepted standard of time, usually for the purpose of providing a precise or obj ective baseline against which to measure events. 2. A signal generated by measuring some repetitive event which is then com- pared to some standard or clock. 3. A signal simulta- neously recorded with data to provide a measure or standard against which the data can be analyzed. 4. A regularly emitted signal against which other time-re- lated events can be synchronized. TINA Telecommunications Information Networking Architecture. A networking telecommunications soft- ware architecture intended to be developed into a glo- bal standard. See Telecommunications Information Network Arc hi tecture Consortium. TINA-C See Telecommunications Information Net- work Architecture Consortium. tinned wire Wire that has been treated with tin to provide insulation and/or to facilitate soldering. Com- mon on copper wire. tinselA fine, very long thread or strip of metal some- © 2003 by CRC Press LLC times wound around electrical conductors between the insulator and the main core or wire. Because of its properties, tinsel is used in cables that need to be tightly wound or very flexible (such as phone hand- set cords). tint Lighter or darker values ofa particular color; hue. Tints are created by successive additions of white or black pigments, or by successively increasing or de- creasing values of red, green, and blue (RGB) at the same time. Greater amounts of each color of RGB will produce lighter tints and lesser amounts will pro- duce darker tints. tip 1. The line or connection attached to the positive side ofa circuit or battery. 2. In two-wire telephone wiring, the tip is traditionally the green wire attached to the positive side of the circuit at the central switch- ing office. The name originates from the configura- tion of a manual phone jack in an old telephone switchboard in which the large plug was divided into two sections, with an internal wire electrically con- nected to the tip of the plug, and another wire to the ring around the plug partway up the jack nearer the insulated cord. See ring, tip and ring. tip and ring Historically, the tip and ring designa- tions derive from the configuration ofa phone jack from a manual switchboard, called a cordboard. The tip was the positive circuit connected to the tip of the jack, and the ring was negative, located slightly away from the tip encircling the jack, sometimes called "sleeve." Later the tip and ring became standardized to correspond with the green and red color-coded wires traditionally used to install phone line services. Often telephone wire is composed of four wires with red, green, black, and yellow sleeves. Since dual lines have become more common in small businesses and in some homes, the black and yellow lines are used for tip and ring, respectively, for the second line. While these codes are standardized in North America, there are variations in other countries and in larger installations with multiple phone lines. tip jack,pup jack One of the simplest connectors, a tip jack has a single, usually round, contact point plug that fits into a matching single-hole plug. TIPHON See Telecommunications and IP Harmo- nization Over Networks. TIRKS Trunk Inventory Record-Keeping System. A commercial product from Telcordia that aids in plan- ning, inventorying, and assigning the telephony cir- cuit order control and circuit provisioning of inter- office equipment and facility inventory. FEPS is a component of TIRKS that provides a range of auto- mated software tools for planning and provisioning interoffice facilities and transmission equipment. TIROS Television Infrared Observation Satellite. A historic series of global polar-orbiting meteorological satellites developed by GSFC, built by RCA, and managed by the Environmental Science Services Administration (ESSA). It was followed by the TIROS Operational System (TOS), then by Im- proved TIROS (ITOS), and subsequently the NOAA satellites. The TIROS spacecraft included low-reso- lution television and infrared cameras. The TIROS craft 1 to 10 were launched between 1960 and 1965 into low Earth orbits. TIROS-N was launched in 1978. In general, they looked like cylin- drical "mirror balls," studded as they were with so- lar cells, and were about the size of an oil barrel sliced in half. Spiny leglike antenna protruding from the flat end of the cylinder gave them an insect-like look. TIROS systems provided the first meteorological data for weather forecasts that were received from space. Continuous coverage of the Earth's surface began in 1962 and proved the feasibility of space data for me- teorological research and forecasting. Remote-Sensing Satellite An artist sconception of the antennas, sensors, and solar cells in the TIROS 7meteorologicalsatellite, as envisioned in April 1961. {NOAA In Space Collec- tion.] TIROS NINOAA ProgramA remote-sensing satel- lite program based on the TIROS satellite series that was initiated to improve upon the operational capa- bilities of the original TIROS numbered series from the 1960s and its successors in the 1970s. In contrast to the earlier barrel-shaped TIROS sys- tems, the TIROS- N satellites were longer and more rectangular, and about three times larger. The systems were three-axes stabilized and Earth-oriented. Improvements in sensing technologies and solar power were incorporated into the later TIROS/N se- ries which includes a number of successful and failed satellites beginning in 1978 and continuing into the late 1990s and present. ITROS-N satellites carried the Advanced Very High Resolution Radiometer (AVHRR) for day and night sea surface and cloud- top sensing. An atmospheric sounding system was also included, as well as a solar proton monitor to detect energetic particles from the Sun that might sig- nal an upcoming solar storm. 1itanic, RMSThe famous, ill-fated ''unsinkable'' ship that sank in 1912, with hundreds of lives lost, while crossing through ice fields north of Canada. The ra- dio operator of the Titanic sent distress calls, but two of the closest ships dido 't receive the communications, as 24-hour watch programs and radio regulations had 933 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary not yet been established (this changed after the sinking of the Titanic). Fortunately, however, some of the sea-goers were saved by the Carpathia, who came to their rescue after receiving the radio distress call. The sinking of the Republic, an earlier ocean-going ship, had a strong influence on legislation requiring wireless communications systems to be installed on ocean-going vessels. Due to the wireless distress calls, all but two of the hands on the Republic were saved. The sinking of the Titanic resulted in further legislation associated with keeping those communi- cation lines open and monitored 24 hours a day. See the JASON project, MARECS, MARISAT. TL See tie line. TLD See top level domain. TLF See trunk link frame. TLP See transmission level point. TLS transparent local area network (LAN) service. TLS Protocol See Transport Layer Security Proto- col. TLV type, length, value. An encoding approach used in Basic Encoding Rules for the information content ofelements. TM I. terminal multiplexer. 2. traffic management. A term associated with network transmission cell traf- fic flow, monitoring, and control. See cell rate. TMA Telecommunication Managers Association. See Communications Management Association. TMC traffic management center. TMGB See telecommunications main grounding busbar. TMN See Telecommunications Management Net- work. TMS 1000 A one-chip 4-bit microcomputer intro- duced by Texas Instruments in 1972. Arguably the second microcomputer ever released with the Intel MCS-4 chip set, it never gained popularity. TMSI See Temporary Mobile Station Identifier. TOGAF See The Open Group Architectural Frame- work. toggle 1. In general, a two-state process or switch. 2. Flip-flop. An electrical current that alternates in in- tensity at two distinct levels, or which has two states: on or off. 3. In software applications, a button or icon that has two states or positions. 4. In computer pro- gramming, a flag that is either set or not set, on or off. Toggles are very commonly used to keep track ofsoftware configuration settings. toggle switch A switch that moves between two po- sitions typically representing two states: on/off, high! low. (Three-state switches are sometimes also loosely referred to as toggle switches.) A traditional buildinng switch that turns a light on or off (in contrast to a dim- mer switch) is a common type oftoggle switch. In aviation and audio equipment, a small narrow switch rounded on the end and tapered more finely at the point of attachment, roughly the shape of a baseball bat is sometimes called a bat switch. This type ofswitch is common in the aviation and audio industries where quick toggle adjustments are needed and many components are crowded for space in a small area. token On a Token-Ring network, a status/priority information block used in coordination oftraffic on the network. A token consists of a 24-bit frame that operates at the Media Access Control (MAC) level. It is continually passed around the ring in one direc- tion and consists of a start delimiter (SD), an access control (AC) field, and an end delimiter (ED). Most of the information for controlling events is contained in the AC. It is further subdivided into a 3-bit prior- ity field, a token bit (zero indicates it is a token), a monitor bit, and a 3-bit reservation field that lets the Token-Ring Basic Frame Components Item Abbreviation Notes Starting Delimiter SD Indicates the beginning ofa frame. Access Control AC Contains the Priority, Token, Monitor, and Reservation bits. In a frame, a workstation can only change the Reservation bits in the access control field. Only the active monitor can change the "M" bit, and only the workstation or device changes the Token bit. Frame Control FC Indicates the type of frame: data frame or maintenance frame. A maintenance frame is used by the protocol to manage the ring. Destination Address DA Physical or NrC address of the receiving workstation or device. Source Address SA Physical or NIC address of the sending workstation or device. Information Layer control, routing control, and data. Frame Check Sum FCS Error checking at the destination. Ending Delimiter ED Indicates the end of a frame. If one of multiple frames or the last frame in a transmission, it's an I bit; if an error occurred, it's an E bit. Frame Status FS Indicates ifa frame has been recognized and copied by the destination station. 934 © 2003 by CRC Press LLC station get in the priority queue for future transmis- sion of frames. A token is reissued after use by a sta- tion of the suitable priority, and continues on its way. See token-passing, Token-Ring frame, Token-Ring network. Token-Ring interface coupler TIC. A Token-Ring local area network (LAN) port that is typically in- stalled on a computer peripheral network interface card (NIC). The TIC facilitates the connection of the computer to the local network. token latency In a token-passing scheme, the time it takes for the token to make it all the way around a token-passing local area network. See token-passing, Token-Ring. token-passing A process on a Token-Ring network by which status/priority tokens are used as a mecha- nism to coordinate traffic around the unidirectional ring. A token is a 24-bit frame that operates at the me- dia access control (MAC) level. It consists ofa start delimiter (SD), an access control (AC) field, and an end delimiter (ED). The token-passing continues around the ring where each station checks the prior- ity before adding frames to the traffic on the ring. Once a token has been used, assuming the proper pri- ority, it is sent out again by the transmitting station to continue its journey around the ring through each station, carrying out the same sequence of events, ac- cording to priority levels. Token-Ring frame A Token-Ring frame in the IEEE 802.5 specification consists of the components speci- fied in the Token-Ring Basic Frame Components chart. Token-Ring Interface Processor TRIP. A Cisco Systems high-speed interface processor with two or four Token-Ring ports, which can be independently set to speeds of4 or 16 Mbps. Token-Ring network TR network. A local area net- work developed by IBM in the mid-1980s, based upon a star or ring topology, that is, with nodes con- nected either directly to one central hub, or in a con- tinuous loop not requiring termination. The token- passing is a scheme for data transmission between the stations which prevents collisions from different workstations sending messages at the same time. A workstation cannot transmit until it receives permis- sion, that is, a token of the proper priority. The token is passed from station to station around the ring in one direction. At each station, the priority is checked before a frame is transmitted on the ring. Token- Ring uses a source-routing system that moves information among stations based upon information in data packet headers, thus uti tizing inexpensive bridges, a system different from Ethernet LANs. Speeds are up to about 16 Mbps, a limitation that has been addressed in High Speed Token-Ring, and throughput is about 60 or 70%, somewhat higher than Ethernet. Frames hold about 4000 bytes. Token-Ring LANs are sometimes combined with Ethernet LANs. They typically run over copper twisted-pair cables, although some are now implemented with fiber. Since IBM's introduction, Token-Ring has been de- veloped into a Media Access Control (MAC) level standard protocol by the IEEE (802.5). A Fiber Distributed Data Interface (FDDI) network employs various token-passing concepts using dual rings to provide redundancy and fault tolerance. See Ethernet, Fiber Distributed Data Interface, High Speed Token-Ring, ring topology, topology. TokenTalk An Apple Computer Macintosh-based implementation ofa Token-Ring local area network. See AppleTalk, Token-Ring network. toll call Any call to a location outside the local ser- vice area, so called because it is billed at a rate above and beyond the local subscriber service. A long dis- tance call. toll denial Denial of service outside the local service area. Toll denial may be part ofa private exchange in order to limit calls to local calls, except as autho- rized. Toll denial may also be set up on an individual subscriber line (e.g., a subscriber who is behind in payments on long distance charges), or a line in a col- lege dorm, or other location where potential toll abuse or fraud may occur. It may still be possible to make toll calls by going through an operator or entering authorization codes. See toll diversion, toll restriction. toll saverA feature of answering machines and some computer software programs that lets you call into an answering machine from a long distance location and know whether there are any messages before the line is connected. The system is based upon the num- ber of rings, usually four or two. With toll saver en- abled, if there are no messages, the answering sys- tem will ring four times before answering. If there are messages, it will answer on two rings. That way, if the caller hears three rings, there are no messages, and he or she can hang up before the machine answers on the fourth ring and save the long distance charge. toll terminal A phone system set up only for long distance calls (toll calls). Toll terminals expedite long- 1~~t~~cI0~~~~i~~~~~~~:~~~I~~f :a~b~~~ • a secure location, accessible only to authorized callers. tone above band TAB. A form of linear broadcast signaling used in conjunction with single sideband suppressed modulation. In TAB, corrections are ap- plied to the received signal, as needed, to produce recognized pilot tones above the frequency of an in- formation signal (as opposed to its center), to correct the accompanying information signal. Transparent tone above band (TTAB) is the same essential idea except that the tone is explicitly chosen to be outside the hearing range audible to humans. See tone in band. tone dialing A system of audio tones called dual tone multifrequency (DTMF) used to generate distinct sig- nals with which phone numbers and symbols can be transmitted. Frequencies are selected in such a way that dual tones are not harmonically related. Each tone is actually a combination of two tones, high and low, which are decoded when sent down the line to the switching office. The high tone is usually slightly louder than, or at least as loud as, the low tone. The tones range in frequency from about 697 to 1633Hz. Two advantages of tone over pulse dialing are speed 935 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary and flexibility. As direct-dial long-distance services became available, numbers became longer, and it takes more time to dial a number on a pulse phone, partly because of the mechanical act of rotating the dial and partly because the dial has to return to the base position. Touchtone systems also provide more options. With a combination of digital processing and touchtone signals, automated menu systems can be accessed through the phone. These are now widely used by banks, mail order houses, and others. See pulse dialing, DTMF, touchtone dialing. tone generator Any device or software application that generates tones. These may be at a particular fre- quency or may vary. Tones can be generated in the audible frequency range for humans, or higher ranges for electronic detection. Tone generators may be used as diagnostic devices on telephone networks. See buzzer. tone in band TIB. A form of linear broadcasting modulation in which corrections are applied to the received signal, as needed, to produce recognized pilot tones at the center of a baseband information signal, thus making it possible to correct the accom- panying information signal. F olWard signal regenera- tion may be used to enhance TIB. Linear modulation techniques provide narrower channels than frequency modulation techniques, thus making it possible to increase the number of channels in a specified amount of space. By the mid-l 980s, transparent tone in band (TIIB), which uses a tone frequency inaudible to the user, was being developed for use in mobile radio networks, for example, to help reduce fading loss. TTIB has become a standard in North America and Europe. See linear modulation, tone above band. tone probe A network diagnostic device for testing voice and other audio networks by detecting and am- plifying acoustical signals. The probe may be passive, detecting only existing signals, or may be active, sounding a tone that is read by adetector somewhere else on the system or by the probe generating the tone (which can then read the echo). tone receiver unit TRU. The electronics in a tele- phone receiver which detect and interpret touchtone codes. TOP See Technical Office Protocol. top-down An organizing or processing hierarchy that distributes itself downward, usually in a branching pattern. Top-down often implies higher priority or more generalized functions or items at the top of the hierarchy. Thus, a top-down outline lists more impor- tant concepts first, a top-down personnel chart usu- ally shows executive managers at the top, a top-down phone system starts with priority-listed agents, etc. Top Level Aggregate TLA. An IPv6 prefix and a cov- eted commodity to the Internet community, the pro- posed assignment of Top Level Aggregates to privi- leged companies caused controversy. To quell the objections, TLAs were significantly increased and TLA requirements were removed from the IPv6 specification. Many Internet developers are con- cerned with preventing the development of a VIP Network Topology Examples A c r~.·I.· LzI These are three common topologies for interconnecting local area networks (LANs). The star topology (A) is a popular way to interconnect computers, printers, and other peripherals with signal negotiations through a central hub (e.g., "thick" Ethernet). If a system on the network becomes nonfunctional, the network as a whole continues to intercommunicate. The ring topology (B), as in Token-ring networks, is an older network topology that is still used in many LANs. In its simplest configuration, it is notfault-tolerant, however; if one system goes down, the networkgoes down, due to the missing link in the ring. In FDDI ring-based networks, there are dual rings to provide redundancy in case of a break in the link in the main ring. The bus topology (C) is popular with daisy-chainable peripherals and with "thin" Ethernetworks that don thave too many systems attached. It is also used in certain backbone connections with LANs as the tributaries. The ends of the networkare typically be terminatedon bus topologies to inform the system that there are no more devices beyond a certain point. 936 © 2003 by CRC Press LLC system on the Net. See IPv6, Next Level Aggregate. top level domain TLD. A hierarchical subset of the domain name system (DNS) which has been further subdivided into generic top level domains (gTLDs) and country code top level domains (ccTLDs). The distinction is administrative rather than functional; TLDs all theoretically have the same access and con- nectivity to the Internet. Within individual designa- tions, some domain name extensions are open and some are restricted. For example, the popular .com designation used primarily for business entities is unrestricted, whereas the .gov designation is restricted for assignment to u.S. federal government agencies. Country code TLDs are open or restricted to varying degrees depending on the country maintaining the designation. Country code TLDs include .ca for Canada, .uk for the United Kingdom, .au for Austra- lia, etc. By 1999, it was estimated that almost 100,000 domain names were being registered per month, with demand steadily increasing. See the Appendix for a list of domain name extensions. topology, network topology A schematic represen- tation and configuration of the geometric and electrical connections and relationships ofa network and its various routing components. Depending upon the number of servers, terminals, routers, and switches, a variety ofpossible configurations are practical, including token rings, stars, and others. See backbone, mesh topology, node, star topology. See Network Topology Examples diagram. Topology Database Update TDU. The refreshing of interconnections and routing information within a network system to reflect the current connections. The Topology Database may have upper limits as to the number of nodes that can be specified to describe the system. In many systems, there are commands for querying the Topology Database parameters and logs as well as commands for setting the basic operating parameters. For example, the frequency of updates may be logged to help a system administrator deter- mine if configuration parameters are optimally set. topology management In networks, the configura- tion, tracking, and management of connecting de- vices, particularly switches. The software used to manage them will often show graphical images of the various devices and their interconnections in the system. TOPS See Traffic Operator Position System. Torricelli, Evangelista (1608-1647) An Italian physicist and mathematician who invented the torricellian tube, now known as a mercury barometer. Barometers later became important in weather fore- casting and in altitude-measuring instruments, par- ticularly for aeronautics and ionospheric experimen- tation. The technology was also important in the evo- lutionary development of the vacuum tube, the basis for electronics for many decades until transistors and semiconductors were developed. ToS See Type of Service. total internal reflection In a light-guiding cable, the total reflection resulting when light rays guided through a waveguide (e.g., fiber optic filament) impact another material and are reflected back into the origi- nal waveguide. For example, in a fiber optic cable, the cladding has a slightly lower refractive index than the conducting core. When light impacts the cladding at angles that are not too steep (beyond the critical angle), the difference in the refractive index causes the light beam to reflect back into the light core. Total internal reflection is not limited to fiber optic cables. It is characteristic of any optical component that has refractive quantum interactions at the inter- face between optical components. R.W. Woods was one of the first to document some unusual refractive properties in metallic surfaces, in 1902. See refrac- tion; surface plasmon resonance; Woods, R.W. Total User Cell ruC. In ATM networking, a recur- ring count of the transmitted Cell Loss Ratio (CLR), stored in the ruc field. The information is useful in assessing throughput. The CLR may be calculated using the Total User Cell (ruC) and the Total Re- ceived Cell (TRC) counts. touchscreen A specialized computer monitor which is activated by contact with a finger or pointing in- strument. The idea was that it was more natural for people to point than to use a mouse of keyboard. Un- fortunately, holding an arm up for any length of time is uncomfortable, so touchscreens haven't become popular for extended or repetitive work. However, they are suitable for occasional input, as in kiosks and directory systems, and for some types of childhood education. Townes, Charles Hard (1915-) An American physi- cist and professor, Townes joined Bell Laboratories in 1933 and worked there until 1947 after which he became a professor at Columbia University. Begin- ning in the early 1950s, Townes became a significant pioneer in maser/laser technology and collaborated on many projects with Arthur Schawlow. A number of his students and those who interacted with Townes in the Columbia lab also distinguished themselves in subsequent laser technologies. In 1961, Townes became a professor and Provost at MIT and stepped down from Provost in 1966 to devote more time to research. In 1967, he became a profes- sor at the University ofCalifornia (Berkeley). Townes has received many awards for his work, most significantly a Nobel Prize in physics coawarded in 1964. Since 1980 the Optical Society of America has annually awarded the Charles Hard Townes Award for outstanding work in quantum electronics. See Basov, A.; Capasso, F.; laser; laser history; Prokhorov, A.; Schawlow, A. TP 1. test point 2. transaction processing. 3. transport protocol. 4. twisted pair. TPA See Telephone Pioneers of America. TPDU See Transport Protocol Data Unit. TPEX twisted pair Ethernet transceiver. TP. See tracks per inch. TPOS See Training, Planning & Operational Sup- port. TPWG See Technology Policy Working Group. TQM total quality management. A management phi- losophy and means of putting it into action to develop 937 i., • '.'." :) ~:~~ © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary and maintain quality principles in commerce, service, and manufacturing. Quality assurance and ISO-900x certification are two kinds of tools in the TQM arse- nal. See ISO 9000. TR transmit/receive. tracer A diagnostic tool for tracing a link through a circuit. In fiber optics, a tracer shines a visible light into the lightguide so atechnician can check whether it is following the appropriate path and making it all the way through the lightguide (e.g., there are no breaks or excessive bends). An invisible beam (e.g., infrared) may also be used if an appropriate detector is at the destination point to detect the incoming light. A fault locater is a type oftracer that uses apowerful laser light source that can illuminate through the fi- berjacket into the fiber to reveal anomalies such as a break in the lightguide. See optical spectrum analyzer, reflectometer. traceroute A Unix shell utility written by Van Jacobson at Lawrence Berkeley Labs which seeks out and displays the path of a transmission packet as it travels from host to host, detailing the hops in the path. Traceroute sends an IF datagram to the desti- nation host, then it iterates through each router, dec- rementing TTL, discarding the datagram, and send- ing back ICMP messages until the destination host is reached. Traceroute is extremely useful as anetwork diagnostic and optimizing tool and often used in con- junction with ping. See ping. The Traceroute Example inset below shows a sample of traceroute output showing the IF numbers, hops, and packets. trackball A hardware peripheral device which re- ceives tactile directional input and transmits it to a computing device. The information transmitted is similar to that ofa mouse or stylus, and is often used in conjunction with graphical user interfaces (Gills). Unlike a mouse or stylus, a trackball is generally fixed in place, with physically separate buttons. Trackballs are common in video arcade games and on laptop keyboards to increase portability. See joystick, mouse. tracks per inch TPI. A measure of the density of a recording medium such as a phonograph record or formatted hard drive. The tracks may be physical (as in grooves) or virtual (as in a logical segmentation on a drive that varies according to the file standard and/or operating system). TRACON Terminal Radar Approach Control. An airfield navigation radar system designed to aid in landing approaches and takeoffs. In commercial air- ports, the TRACON is typically housed in the air traf- fic control tower (ATCT). The Federal Aviation Ad- ministration (FAA) has almost 200 ofthese radar ap- proach facilities in the U.S. A TRACON control room may accommodate a number ofoperators and typi- cally has backup generators to ensure air traffic safety in the event of power outages. As cities grow, the need to support increased and more complex air traffic grows as well. To meet this need, the Federal Avia- tion Agency (FAA) has been working on projects to consolidate individual TRACON s into what is termed Large TRACONs. tractor feeder Asprocketed paper alignment device used mostly on impact printers. It provides more pre- cise control of positioning than most roller feeders by preventing slippage. The tractor feed resembles a pair ofshort regular series of inverted cleats which fit through corresponding holes in tractor feed paper. Tractor feed mechanisms are especially useful for multipage documents (invoices, checks, etc.) on dot matrix printers. tradesecretInformation, data, process, or procedure which would lose its commercial value if revealed to outsiders. Nondisclosure agreements (NDAs), policy statements, and inservice training are mecha- nisms which restrict external communication oftrade secrets. If trade secrets are not specifically identified by an employer, it may be more difficult to stop or prosecute an offender who has willfully or inadvert- ently revealed them. See patent, copyright, nondis- closure agreement, trademark. trademark A legal designation for the right of an association to the use of a mark in trade. It can con- sist ofa word, phrase, or symbol sufficiently unique Traceroute Example $ traceroute abiogenesis.com traceroute to abiogenesis.com (207.173.142.184), 30 hops max, 38 byte packets 1 chapman.nas.com (198.182.207.6) 322 me 252 me 251 rna 2 orthanc.nas.com {198.182.207.1} 251 rna 247 rna 275 rna 3 milo-s4.wa.com (204.57.232.1) 277 me 257 rna 296 rna 4 dilbert-fe4-0.wa.com (192.135.191.254) 530 rna 303 rna 273 rna 5 dogbert-f4-0.nwnexus.net (206.63.0.254) 263 me 282 me 286 me 6 borderx2-hssi2-0.Seattle.mci.net (204.70.203.117) 306 me 277 rna 373 me 7 core2-fddi-l.Seattle.mci.net (204.70.203.65) 288 rna 511 rna * 8 bordercore1.Denver.mci.net (166.48.92.1) 299 me 323 me 293 me 9 electric-lightwave.Denver.mci.net (166.48.93.254) 294 me 351 rna 313 rna 10 H3-0.1.scrlib01.eli.net (207.0.56.162) 329 me 394 rna 591 rna 11 gW2-CALWEB-DOM.eli.net (208.131.46.46) 730 ma gwl-CALWEB-DOM.eli:net (208.131.46.30) 507 roB gw2-CALWEB-DOM.eli.net (208.131.46.46) 357 me 12 abiogenesis.com (207.173.142.184) 362 rna 358 me 350 me 938 © 2003 by CRC Press LLC to be distinguished from others in the same general industry. Provided it is not already owned by another entity, a trademark becomes valid as soon as a com- pany uses it in trade according to certain stipulations, provided the company continues using it. You can- not com~ up with a trademark idea, not use it, and claim it later if someone else uses it. Trademarks may be registered federally for a fee, although this is not required. The motivation for trademark registration is to provide prima facie evidence in the event ofa legal dispute. Unregistered trademarks must be iden- tified with a ™ symbol, and registered trademarks must be identified with an ® symbol. Policing of trademark violations is not a responsibility of the fed- eral government or of the agency that registers a trademark; it must be done by the company seeking to protect the trademark. Trade names are similar to trademarks and are registered at the state level. There can be more than one company using the same trade name, if the line of business is sufficiently different to prevent confusion. The Commerce Department's large database of patent text and images, 800,000 trademarks and 300,000 pending registrations dating from the 1800s, has been gradually uploaded to the Web since 1998. See copy- right, patent. http://www.supot.gov/ Traf-O-Data The first business partnership of Paul Allen and William R. Gates, founded around 1972, growing out of the business experiences of the less formally organized Lakeside Programming Group. Allen and Gates worked together on a variety of soft- ware projects including an automobile traffic flow system. At about the same time, they prototyped an early microcomputer based upon the recently released Intel 8008, with the participation of a hardware de- signer, Paul Gilbert. They made some tentative at- tempts to sell this early machine, but it didn't work during an early demonstration. At about the time Gates graduated from high school, Allen encouraged him to join him to start a company to build and sell computers based upon the Intel 8080 chip set, but Gates wasn't fired up about the idea ofa hardware company, and his parents were encourag- ing him to continue his post-secondary education. The majority of Gates and Allen's subsequent efforts were software-related, most significantly, a BASIC inter- preter for the Altair, and a disk operating system for IBM, which resulted in the founding of Microsoft Corporation. The subsequent success of the company was due to sales of software, primarily operating sys- tems and business applications, and Apple Computer became the small business success story in computer hardware. traffic A tenn often used on large communications systems to describe communications signals, data, cells, or packets which comprise the information and signaling associated with the transmissions. The term is sometimes also used to describe the overall flow and pattern of traffic in the context of the system it is on, as in traffic congestion, traffic flow, traffic moni- toring, traffic engineering, traffic routing, etc. In te- lephony and various systems that are largely analog based, the term may be used to describe the flow of information in the context of calls, as in call attempts, call connects, call volume, etc. In digital systems, it is often used in a more specific sense to indicate num- bers of packets or cells. See leaky bucket. traffic capacity A measure of the capability of a system to carry a certain maximum number of calls, cells, frames, or packets, depending on how capac- ity is measured or data carried on that particular sys- tem. The maximum capacity may not be a fixed num- ber, as on systems where multiple channels may be aggregated to carry certain broad bandwidth types of information. On other systems, where one or two wires can carry one and only one communication, traffic capacity is more likely to be expressed as a set amount. Traffic capacity is used in systems design and marketing to provide buyers a general guideline as to the capability ofa system. For example, a rural phone switching system in a small community may only require a capacity of 20,000 call seconds (usu- ally expressed in increments of hundred ca~l seconds) per hour during peak calling times, providing a mea- sure of whether a system can meet or exceed those needs. See traffic concentration. traffic concentration A measure of communications traffic that indicates how different peak traffic peri- ods are compared to traffic on the whole. In telephony, the service day is usually broken down into hours for traffic monitoring to determine high and low traffic periods. Traffic concentration is typically expressed as a ratio of the traffic (number of calls) during the busiest hour to the total traffic during a 24-hour pe- riod. This may further be calculated over a period of weekdays, weekends, or 7 -day weeks to provide sta- tistical averages. traffic engineering In more traditional communica- tions systems, traffic engineering is the estimation and application of the type, quantity, and configuration of devices and equipment required to meet the needs of a predicted number of users of the system being designed. Experience, trial and error, probability theory, similar system comparison, and insight are all brought into play in designing a system to meet cur- rent and predicted future needs. This system works quite well with traditional telephone switching sys- tems and local area networks. As systems become more complex, however, and dis- tributed digital data systems more prevalent, traffic engineering, once the initial equipment is set in place, becomes an even more esoteric process, with much of the configuration and selection carried out by com- puter software, not just through physical connections. Virtual networks are now laid over physical networks, resulting in several levels of traffic engineering. When these networks are interfaced with a global network like the Internet, then prediction of the num- ber of potential users becomes more difficult and less important than incorporating flexibility and scala- bility into the system to handle unpredictable traffic loads and activities. At this level, traffic engineering becomes a collaborative activity between program- mers and traffic engineers, with careful evaluation of 939 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary data and message priorities - scheduling and incor- porating deliberate delays, for example, so some types of traffic can be set to transmit during off-peak hours. On data networks, many traffic decisions are now built into the software on servers, gateways, routers, and some of the high-end switchers. traffic load The sum total of the traffic on aparticu- lar system or portion ofa system, such as a specific trunk, leg, or hop, measured at a particular point in time, or during aparticular specified range of time. traffic monitor A mechanism for keeping track of traffic on a system. On data networks, some of the software included for system administrators allow the monitoring of various processes, and typically dis- play them as sampled or realtime graphical charts. Thus, CPU usage, number of users, number of trans- missions, level of traffic, etc. can be visually assessed, and statistics derived from computerized traffic and analysis can be stored and evaluated to make changes as needed. The results of the monitoring are some- times directly incorporated into other software on the system which makes adjustments to priorities, number of users permitted online at one time, and other pa- rameters that can be changed to increase or decrease the traffic to optimize use of the system. Sometimes traffic monitoring is a very simple mecha- nism. One of the simplest and most familiar applica- tions is on modems, where little blinking lights give some indication of how much data are traveling through the modem, and when. If auser is download- ing a large file from a Web site and those lights stop blinking, it's possible that the connection has been dropped or there is a glitch in the system. In ATM systems, traffic monitoring is an essential aspect of preventing network congestions and bottlenecks, and some cells will be flagged as to their discharge eligi- bility. See cell rate, leaky bucket. Traffic Operator Position System TOPS. A system to support telephony operators from a toll switch, TOPS was developed by Northern Electric (later Northern Telecom) in the early 1970s, a time when manual cord-based operator terminals were poised to be gradually replaced by automatic stored-program switches. The historic TOPS-I utilized an Intel 8008 CPU; the first TOPS office was installed in 1975 in Alaska. As computer technologies improved, TOPS was upgraded to faster, more versatile processors. traffic overflow Asituation where demand exceeds capacity. When overflow occurs, the traffic is either routed to another trunk or leg, or it is rejected and a signal sent to the user in the form ofa signal (like a fast busy) or a text message (as a broadcast on a com- puter system). In some data networks, particular pack- ets may be discarded if there is traffic overflow, or they may be routed back to the sender. traffic path The physical or virtual pathway taken from the sender to the receiver. This may be fixed, as in direct wire communications and smaller data net- works, or it may be flexible, as in switched systems and many larger data networks. On very small sys- tems, where the setup is known and doesn't often change, a fixed traffic path may be the fastest and 940 most practical implementation. In dynamic data net- works, the communication may not be quite as fast, but the system has an advantage in that it can toler- ate and adjust to unpredictable changes. A path in a phone system usually passes from the sub- scriber to a demarcation point, usually ajunction box between the internal and external wiring, through one or more switching centers which are connected with pathways called trunks, or sometimes through a wire- less link during part or all of the transmission. In a digital computer network, the data may pass from the sender through various servers, gateways, switches, and routers; each section in the path is called a hop or a leg, with the various terminal points generically called nodes. A data network transmission may also be wireless for part or all of the path. traffic policing In ATM networking, a mechanism which detects and controls cell traffic according to specified parameters. See cell rate. traffic recorder A means to record traffic on a speci- fied transmissions channel in order to monitor capac- ity, load, efficiency, etc. It mayor may not be paired with software that helps analyze the traffic. traffic reporting In networks, information on traf- fic flow gathered and organized by external analyz- ing devices or internal monitor agents. This informa- tion about packet volume, distribution, collisions, and errors may be reported in the form of tables, ASCII graphs and charts, or images, and is essential for con- figuration, tuning, and troubleshooting. traffic shaping In ATM networking, a mechanism which shapes or modifies bursty traffic characteris- tics in order to create the desired traffic. See cell rate. train v. To instruct, teach, indoctrinate, or drill. Train- ing is an important component of any computing sys- tem that must recognize input beyond point and click or keyboard instructions. In pen computing, hand- writing must be interpreted into commands, and it is usually necessary to train the system, by successive trials and feedback, to recognize an individual's style of writing. Some camcorders have eye-controlled systems which need to be trained to track the direc- tion offocus of the user's eye. In voice recognition systems, software is trained to recognize an individual's mode of speaking. OCR systems can be trained to improve recognition ofunfamiliar or un- usual character sets. While software training systems are not perfect, they have evolved to the point where they do much useful work, and improvements in tech- nology and software algorithms indicate that some day natural methods ofcomputer input may super- sede keyboard and mouse entry for many applica- tions. training An automatic feature of some hardware and software systems to evaluate the characteristics of incoming signals (timing, delay, etc.) or information (handwriting, voice, etc.) and improve performance or recognition through successive adjustments and feedback. See artificial intelligence, expert system, robotics. Training, Planning & Operational Support TPOS. Asupport function within the Operations Division of © 2003 by CRC Press LLC the National Communications System (NCS). TPOS coordinates telecommunications operational planning among NCS elements, provides educational semi- nars, cooperates with other federal and regional or- ganizations, and participates in the Regional Inter- agency Steering Committee (RISC) meetings. See National Communications System. transaction 1. An agreement, or exchange of infor- mation or goods, between two or more parties or en- tities. 2. A business transaction, which may be sub- ject to various recording requirements (contracts, taxation, audit records, etc.). 3. An entry into a data- base or spreadsheet. transaction, network Any ofa number of situations in which information or signals are exchanged, passed on, recorded, or evaluated. Examples of network transactions include protocol determinations and con- versions, security-level evaluation and processing, routing, transmission between nodes, error process- ing, etc. Transaction CapabilityApplication Part TCAP. In the SONET specification, there are several chapters regarding the function, formats, and definitions for TCAP provided in the ANSI T 1.114-1996 document. Transaction Team A group with the Office of Gen- eral Counsel that coordinates the Federal Communi- cation Commission's (FCC's) review of applications for major transactions and changes. The Team was announced in January 2000 as a response to an un- precedented number of significant mergers in the tele- communications industry and was tasked with streamlining the review process while still safeguard- ing the public's interests. transaction tracking A system of recording each instance ofa transaction and, sometimes, the actual transaction or its outcome. In database or spreadsheet applications, for example, each transaction may be recorded as entered, in order to prevent loss of data due to a series oftransactions not having been saved at regular intervals. This type of live recording of transactions frees the user from worrying about "saves" and ensures that, under most fault situations, no more than the most recent entry may be lost. See ticket. transatlantic cable A communications link across the Atlantic Ocean incorporating a bundle of wires or, more recently optical fibers, within a tough, cor- rosion-resistant insulating protective sleeve. The cable is laid along the ocean bottom in regions and at depths where the likelihood of severing by boat an- chors is less. Maintenance of oceanic cables is a com- plicated business, so much emphasis is put on build- ing and installing them correctly in the first place. The invention of the telegraphy in the 1800s provided a strong motivation for laying a cable to bridge the communication gap between North America and Eu- rope. Since postal messages could take from several weeks to several months to traverse the Atlantic, there was a potential goldmine in the provision of cable services. Samuel Morse was one of the more promi- nent inventors who suggested the feasibility ofa cable between North America and Europe. Only three decades elapsed between the development of the first commercially practical telegraphs in En- gland and America and the laying of the first work- ing oceanic cable. The first attempts did not succeed, however, due to problems with installation, insula- tion, and capacitance over long distances, but im- provements in insulation, and trial and error experi- ence, resulted in eventual success. The first working transatlantic cable was installed in August 1858, initiated by F.N. Gisborne's efforts to interlink maritime Canada, and financed and pro- moted by Cyrus W. Field. A more permanent instal- lation was realized by Field and his associates in July 1866. An additional link was established between Ire- land and Canada, in 1894. Cables to other continents and through other oceans followed as the technology improved. In the 1870s and 1880s, companies were formed to lay cables to South America and Africa. With increasing demands for high-speed wideband communications links for data communications, transatlantic cables are more important than ever; the old wire cables are being replaced by fiber optic cables and new cables are being installed to link re- gions not previously interlinked. See British Indian Submarine Telegraph Company; Field, Cyrus West; Gisborne, Frederic Newton; gutta-percha; Pender, John; Submarine Telegraph Company. Historic Transatlantic Cable Telephone Call PrimeMinisterRichardBennett (with cabinet mem- bers) speaking over a transatlantic telephone to George Perley at the British Empire Trade Fair at Buenos Aires, Argentina, in March 1931. [National Archives of Canada National Film Board image.] Transcontinental Cable A generic euphemism for the U.S. Defense communications system stretching from Washington, D.C. to California and Florida dur- ing and after World War II. It was called this because of the labeling of the dig warning signs located in fields and near garden shed-like repeater stations po- sitioned every few miles along the cable routes across the country. See L CXR. transceiver Device which transmits and receives within a single unit, often sharing circuitry to reduce size and weight. See transmitter, receiver. 941 © 2003 by CRC Press LLC . temporo-spatio processing, this type ofprocessing is used in appli- cations and devices such as infrared motion detec- tors or radar systems which are using time and space as interrelated factors in their decision-making in terms ofprocessing data or signaling an alarm con- dition. Time-space processing is also used in adap- tive beam-forming antenna mechanisms. time-to-digital converter TDC. An. LLC Fiber Optics Illustrated Dictionary and flexibility. As direct-dial long-distance services became available, numbers became longer, and it takes more time to dial a number on a pulse phone, partly because of the mechanical act of rotating the dial and partly because the dial has to return to the base position. Touchtone systems also provide more options. With a combination of digital processing and touchtone signals, automated menu systems can be accessed through the phone. These are now widely used by banks, mail order houses, and others. See pulse dialing, DTMF, touchtone dialing. tone. flexibility and scala- bility into the system to handle unpredictable traffic loads and activities. At this level, traffic engineering becomes a collaborative activity between program- mers and traffic engineers, with careful evaluation of 939 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary data and message priorities - scheduling and incor- porating deliberate delays, for example, so some types of traffic can be set to transmit during off-peak hours. On data networks, many traffic