Fiber Optics Illustrated Dictionary - Part 93 ppsx

Fiber Optics Illustrated Dictionary and suppliers ofcommunications products for mat- ters of public policy and international commerce. TIA is accredited by the American National Standards In- stitute (ANSI) to develop standards for a variety of communication products. See TIAFiber Optic Com- munication Standards chart. http://www.tiaonline.org/ Telecommunications Information NetworkArchi- tecture TINA. A common architecture for building and managing communications services developed by the Telecommunications Information Network Ar- chitecture Consortium in the early 1990s. This archi- tecture logically separates the physical infrastructure and the applications from the need to communicate directly with each another. Control and management functions are integrated and can be placed on the net- work independent ofgeography through asingle Dis- tributed Processing Environment (DPE). See Tele- communications Information Network Architecture Consortium. Telecommunications Information Network Ar- chitecture Consortium TINA-C. An international association ofover 40 telecommunications operators and manufacturers who first came together at a TINA Workshop in 1990 and formed the consortium to cooperatively define a common architecture (TINA) to be promoted as a global standard for building and managing telecommunications services. This work draws heavily on the work of other organizations and standards bodies in order to take advantage of ongo- ing studies and developments, to expedite the progress of the TINA project, and to promote the har- monious cooperation of various groups with similar goals. http://www.tinac.com. telecommunications lines Physical lines, usually metal wire or fiber optic cable, over which commu- nications are transmitted, usually by electrical im- pulses or light. Contrast to wireless communications. telecommunications main grounding bus bar TMGB. An important component of a telecommuni- cations electronic grounding system that extends the building grounding electrode system for a telecom- munications network infrastructure. Typically one per building is housed in an accessible communications closet as a central attachment point for atelecommu- nications bonding backbone (TBB) with one or more telecommunications grounding busbars (TGBs). A TMGB is designed to facilitate low-resistance con- tact between lugs and busbars. It should be directly bonded to the electrical service ground and to a TGB which, in tum, connects to a permanent metallic TIA Fiber Optic Communication Standards Document Designation Description TWEIA-455-164A FOTP-I64 TIAlEIA-455-171A FOTP-171A TWEIA-455-191A FOTP-191 TIA-526-2 OFSTP-2 FOTP-5 FOTP-78 100 Mbps FOTP-87 FOTP-98 FOTP-157 Humidity Test Procedure for Fiber Optic Components Spectral Attenuation Cutback Measurement for Single-Mode Optical Fibers Fiber Optic Cable Knot Test Fiber Optic Cable External Freezing Test Measurement of Polarization Dependent Loss (PDL) of Single-Mode Fiber Optic Components Single-Mode Fiber, Measurment of Mode Field Diameter by Far-Field Scanning Attenuation by Substitution Measurement for Short-Length Multimode Graded-Index and Single-Mode Optical Fiber Cable Assemblies Measurement of Mode Field Diameter of Single-Mode Optical Fiber Effective Transmitter Output Power Coupled into Single-Mode Fiber Optic Cable Single-Mode Fiber Optic System Transmission Design Fiber Optic Connector Intermateability Standards Blank Detail Specification for Single-Mode Fiber Optic Branching Devices for Outside Plant Applications Physical Layer Medium-Dependent Sub layer and 10 Mbps Auto- Negotiation on 850 om Fiber Optics Relevant Technical Committees TIAlEIA-455-87B TWEIA-455-98A TIAlEIA-455-157 TIAlEIA-455-5B TIAlEIA-455-78A TIA-559 TWEIA-604 TWEIA-620AAOO TIAlEIA-785 FO-2.l Single Mode Optical Communication Systems FO-2.2 Digital Multimode Systems FO-2.3 Optoelectronic Sources, Detectors, and Devices FO-2.6 Reliability ofFiber Optic Systems & Active Optical Components FO-6.1 Fiber Optic Field Tooling & Instrumentation FO-6.2 FO-6.3 FO-6.6 FO-6.7 FO-6.9 Terminology, Defmitions, & Symbology Interconnecting Devices and Passive Products Fibers and Materials Optical Cables Polarization-Maintaining Fibers, Connectors, and Components 912 © 2003 by CRC Press LLC structural element of the building. The TMGB should never be bonded to a secondary electrical conduit or pipe, as this may result in different ground potentials between the TMGB and the communications equip- ment grounding. If multiple closets exist in the same building; the TGBs should be bonded to one another and to the TMGB through approved insulated wires to form a TBB. The TMGB resembles a metal cribbage board in that it has pairs of holes punched (all the way) through a thin rectangular board and is supported by brackets and insulators with noncorrosive fasteners. The holes are drilled according to recognized size and spacing standards (e.g., NEMA). It is made ofa conductive material such as copper, and may be plated with an- other metal such as nickel. TMGBs are generally designed to conform to ANSI! TIA/EIA-607 specifications and BICSI recommen- dations and come in avariety of widths and lengths. Once installed, TMGBs should be labeled with warn- ings not to remove the structure or disconnect any of its components. Telecommunications Management Network TMN. A global network management model for Network Elements (NE) and Operation System (OS) and the interconnections between them. Global standardiza- tion provides greater incentives for common interface development. Discussions of O&M aspects of intel- ligent transmission terminals began, and TMN was first formally defined in 1988, with the recommen- dation for M.30 10 (Principles for TMN) published in 1989, in addition to others over the next three years. OSI Management, originating in ISO, was adopted as a framework for TMN to provide transaction-ori- ented capabilities for operations, administration, maintenance, and provisioning (OAM&P). Elements of a TMN interface consist of various definitions, models, and profiles, including architectural defini- tion of TMN entities, OAM&P functionality, man- agement application and information models, re- source information models, communication proto- cols, conformance requirements, and profiles. Telecommunications Policy, Office of OTP A gov- ernment agency, established in 1970 as an Executive Office of the President during Richard M. Nixon's administration. The OTP evolved from the 1968 President's Task Force on Telecommunications Policy. Clay T. (Tom) Whitehead was the first OTP Director. Some of the staff were taken from the ear- lier Office of Telecommunications Management (OTM). The OTP was rolled into the U.S. National Telecommunications and Information Administration in 1978 resulting from reorganization. Telecommunications Policy, President's Task Force on A significant milestone in telecommunica- tions policy development which came about partly because of controversies regarding cable and long distance services. The Task Force was established in 1968 during the term of President Lyndon B. Johnson. Some of the important outcomes of Task Force research included the establishment ofa government agency to deal with telecommunications policy and increased emphasis on competition and deregulation. Telecommunications Policy Research Conference TPRC An annual forum, first convened in 1972 as the OTP conference, for public and private sector scholars and decision-makers to discuss recent em- pirical and theoretical research and the needs of the telecommunications industry. See Telecommunica- tions Policy, Office of. http://www.tprc.org/ Telecommunications Reform Act An act by the U.S. government opening up local and long distance mar- kets to competition. The act included a highly con- troversial provision called the Communications De- cency Act (CDA) which was, after a great deal of dis- cussion and input from the Internet community, de- clared unconstitutional. The Reform Act significantly altered regulations of the telecommunications industry. Telecommunications Regulatory Email Grapevine TREG. An informal organization that carries on regu- lar online discussions about real world issues asso- ciated with taking products and services through the various regulatory processes. This self-help, group an- swers queries and shares experiences, archiving the information on the Web. telecommunications relay service A 24-hour tele- phone service to assist hearing impaired individuals to intercommunicate and to communicate with hear- ing subscribers. This service may have a variety of telebraille, TTY, and voice options. In general, the subscriber calls a telephone agent, who intercepts the call, translates it, and relays it to the callee on behalf of the caller. The calls and call content are confidential. Telecommunications Research Establishment TRE. A once-secret facility at Malvern where com- munications research such as radar research was con- ducted during World War ll. The TRE was established in 1940, evolving from the Ministry of Aircraft Pro- duction Research Establishment (MAPRE). Some of the early research in digital storage devices was car- '. ried out here towards the end of the war. Many of the ]~~. researchers at this facility made significant scientific achievements in a number of fields including radio astronomy. See Small Scale Experimental Machine. telecommunications service This is defined in the Telecommunications Act of 1996 and published by the Federal Communications Commission (FCC), as " the offering of telecommunications for a fee directly to the public, or to such classes of users as to be effectively available directly to the pub- lic, regardless of the facilities used." See Federal Communications Commission, Telecom- munications Act of 1996. Telecommunications Service Priority TSP. A pro- gram of the Federal Communications Commission (FCC) for identifying and prioritizing telecommuni- cations services that support national security and/or emergency preparedness (NS/EP) missions. The TSP regulates, administers, and operates priority restora- tion and provisioning of qualified NS/EP telecommu- nications services to support emergency readiness and response to local, national, or international events or crises that might harm Americans or their property. http://tsp.ncs.gov/ 913 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary Telecommunication Standardization Bureau TSB. The TSB provides support for the standardization sector of the International Telecommunication Union (ITU). As such, it helps to coordinate the work of the lTU - T, provides secretarial services, assists in dis- seminating information, and ensures the publication of various references resulting from the work of the lTU-T. See International Telecommunication Union. Telecommunications StandardsAdvisoryCouncil of Canada TSACC. A Canadian industry-govern- ment alliance formed in 1991 to develop strategies for Canadian and international standardization in in- formation technology and telecommunications. Infor- mation on telecommunications technologies is pro- vided on their Web site. http://www.tsacc.ic.gc.ca/ Telecommunications Technology Association TTA. Established by the Korean Ministry of Communica- tion in 1988, beginning operations in 1992. http://www.tta.or.kr/ telecommuting Virtual commuting to the work site, that is, communicating through various telecommu- nications methods instead of physically traveling to the work site. A number of factors have contributed to the increasing desire for, and availability of, tele- commutingjobs: increasing congestion in cities caus- ing higher housing costs and less availability ofhous- ing; increased traffic congestion; more families with two working parents who don't want to leave chil- dren unattended; improved telecommunications ser- vices, with faster and better transmission, more hookup services through phone lines, and videocon- ferencing options. Telecommuting is not for everyone; many people pre- fer to work under direction or to work in close physi- cal proximity to co-workers, but many work better undisturbed and will use the time saved by not com- muting to produce a higher-quality product. There are also increasing numbers of businesses willing to pro- vide telework options so that they can recruit highly skilled workers from diverse regions. See telework, virtual office. telecomputer, computerTVA TV broadcast system- computer integrated system that allows a user to con- trol program selection or menu options for viewing, such as split screen for more than one show, digital effects, sound options, integration of TV and phone (e.g., on-screen Caller ill on the TV when the phone rings), email and Web access, shopping from home, etc. This is an example of the convergence of the com- puter and broadcast industries. Standards for ATM for the home are being promoted so that standardized commercial consumer systems can be developed which allow these many technologies to link and work together. See Broadband Residential, fiber to the home, Home Area Network, WebTV. teleconference A telephone conference where three or more participants share in a conversation. Confer- ence call buttons or codes are available on some lo- cal multiline systems, and operators can set up con- ference calls across public lines for participants who are distant from one another. See videoconference. telecopier See facsimile machine. 914 teledensity A measure of the number of telephone lines per 100 POPs (individual people) used to as- sess service distribution, economic compromises, revenues, etc. Teledesic, LLC A privately owned constellation of literally hundreds of satellites orbiting at 700 km (LEO) designed to provide switched broadband bi- directional network services, including Internet ac- cess, data, voice, videoconferencing, and interactive multimedia. It is designed to operate at up to 64 Mbps for downlink and up to 2 Mbps for uplink. The top transmissions speed is more than 2000 times faster than standard modems operating over wired phone lines. Connection is through small parabolic antennas. The Teledesic group approached the Federal Com- munications Commission (FCC) in 1994 for a 500- MHz frequency allocation within the Ka-band for this service. In May 1998, Motorola Inc. joined the venture as the prime contractor, bringing in its Celestri technology, along with Boeing Company and Matra Marconi Space, a European satellite manufacturer. In August 2001, the company announced that either Lockheed Martin Commercial Space Systems (LMCSS) or Alenia Spazio (an Italian vendor) would be selected as the prime contractor to build the network as both had experience in building nongeostationary-orbit satellite systems. In November 2001, a talked about merger with another McCaw company, ICO Global Communications was discontinued. In February 2002, an agreement was signed with Alenia Spazio to contract the systems. Teledesic LLC is a McCaw/Gates company sched- uled to launch its satellites in the early 2000s and to be in service by 2005. TeleDirectory A telephone directory service from British Telecom for personal computer users who have a frequent need for directory assistance services (e.g., five or more numbers per day) and wish to ac- cess the number online. Enquiries are billed on aper- number basis. See BT Phonebase. Telefunken A German radio station founded in 1903 soon after Marconi's wireless demonstrations in Lon- don, England, excited the imaginations of radio ex- perimenters and future broadcasters. telegaming Gaming over a distance communications medium (telephone, computer network, postal ser- vice). Telegaming has been around for a long time. F or centuries, people have played long distance chess and backgammon games by messenger and, more re- cently, by mail or phone. Currently it implies an un- broken connection, since that is now possible through computer networks and games like chess and go are routinely played on the Internet. Video arcade games are played on local networks, usually on an Ethernet link, although the term telegaming doesn't apply as well to an activity in which the participants can see or hear one another in the same or next room. telegenic Having characteristics that appeal to tele- vision audiences, such as charisma, talent, humor, relevance (news), or other qualities favored by broad- cast networks and viewing audiences. © 2003 by CRC Press LLC telegram Originally telegramme (France, 1793). A printed record ofa telegraphic communication. Early telegraph signals were transcribed on paper tape as wiggly lines; later, audible signals were interpreted by human operators and written down by hand; and, finally, devices that could interpret the signals into text and impress them on paper as telegrams were devised. For decades the telegram was delivered into the hands of the intended receiver or at least brought to the doorstep. Courier services and facsimile ma- chines are superseding telegram services. See tele- graph system, teletypewriter. telegraph fire alarm That telegraph signals could be used to report fires through signal boxes was realized not long after the invention of the telegraph, and many of the larger communities installed this type of safety system by the early 1900s. The Boston Fire Alarm system was one of the first, following a published description of its feasibility by William F. Channing in 1845. Later, with the help ofa telegraph engineer, Moses G. Fanner, Channing supervised the 1851 city funding and 1852 construction of the first fire alarm telegraph in the world. Originally based on manual crank boxes, painted black, the mechanisms were later changed to pull switches, and eventually dials. By 1881, the fire boxes were changed to red. telegraph history The telegraph was a system of equipment and data encoding that enabled commu- nication over distance, originally through drum beats, signal fires, and signal towers, and later by wires pow- ered by high-intensity batteries. As with many tech- nologies, the telegraph was invented in a number of places at about the same time, and many of the early models were never practically or commercially implemented. In a sense, the technology has come full-circle. Many of the earliest modern telegraphs were optical tele- graphs which gradually gave way to electrical sys- tems and now, 200 years later, we are returning to the use of optics, channeled automatically through fiber rather than being transmitted by humans through air. Lesage had created africtional telegraph as early as 1774, and A. Ampere and P. Barlow proposed early designs as well. 1. Munro reports that someone iden- tified only as C.M. described an electric telegraph in Scots Magazine in February 1753 that suggested a multi-wire system (similar to those later implemented by Campillo in Spain and Sommering in Germany). If so, it is the earliest recorded reference to a modern telegraph system. Samuel T. von Sommering created a 35-wire telegraph based upon electrochemical con- cepts which, in turn, was derived from the work of Francesc Salva i Campillo in Spain, in 1795. Optical telegraphs were developed by Claude and Ignace Chappe in the early 1790s and were probably built upon the ancient tradition of signal fires. The Chappe system used physically coded letters and symbols relayed through a system of towers by hu- man "transceivers." The concept spread to other parts of Europe, including Denmark, where an optical postal telegraph was established in 1801. One of the first practical commercial implementations ofa nonoptical telegraph was in 1837 by C. Wheat- stone and W. Cooke in England. The telegraph in America owed much of its design and development to Samuel Morse and Alfred Vail. Morse's original telegraph caveat (an intention to file a patent) de- scribed a mechanism with a horizontally moved key which made corresponding zigzag marks on a mov- ing paper tape to represent numbers, which were then looked up to find the corresponding words in a refer- ence dictionary prepared by Morse. Vail improved on the mechanics of the key, making it move up and down instead of side-to-side, thus forming dots and dashes with breaks in between on the paper. As this system was simpler and more direct than doing a dic- tionary lookup, it evolved into the system now known as Morse (Vail) code. Their telegraphic invention was demonstrated to the Presidency in 1838. Morse sub- sequently won funding from Congress to construct a telegraph long distance line, carried out the project with assistance from Ezra Cornell, and began to spread telegraphy throughout America in the mid- 1800s. Both Wheatstone and Morse received advice and encouragement on the development of tele- graphic instruments from Joseph Henry in the 1830s. Morse, unfortunately, didn't duly credit Henry's as- sistance. Historic Telegraph Communications Technology One of the early Bell telegraph patent documents. There were many inventors at the time independently makingsimilardiscoveries, and substantial competi- tion to be the first to patent and commercialize the new communication technologies. In its simplest form, the telegraph consists ofa sender (a keying device), a receiver (with a sounder or printer), and a simple code for conveying characters. Early telegraph receiving machines used paper tapes to record messages (Morse's telegraph created a wig- gly line), but operators began to recognize the slightly audible incoming clicks and could copy messages faster than a paper tape could print them, so machines were soon equipped with sounders and resonators to amplify and direct these clicks. Not surprisingly, 915 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary many inventors sought ways to translate the signals into letters that could be recorded directly, as in a tele- gram or teletype-style printout. One of the first to succeed was David Hughes, a schoolteacher, in 1856. In America, messages were sent by shutting current on and off, while in Britain, Wheatstone introduced polar keying, a means of using polarity to convey sig- nals. The concept of polarity is still used today in high-speed data transmissions. In 1866, M. Loomis demonstrated that signals could be sent from one airborne kite to another, when each was strung with fine copper wire of the same length, without direct physical contact. This later lead to his 1872 U.S. patent for awireless improved telegraphic system, although it was some time before his discoveries were put into practical use. By the 1880s, scientific investigations and demon- strations had confirmed the viability of wired and wireless telegraphy. The end of the century then be- came a time ofcreative application of the concepts and evolutionary improvements in speed and practi- cality. In 1895 and 1896, in Russia, A.S. Popow was con- ducting experiments with wireless telegraphy and succeeded in sending a shipboard message to his labo- ratory in St. Petersburg. Unfortunately, due to the se- crecy surrounding Russian naval technology and in- ventions in general, Popow's discoveries were not communicated to the rest of the world, and he did not receive credit for his early experiments. In the late 1800s, telautographs that could transcribe handwriting were created by several inventors such as E. Gray and F. Ritchie. While these were used for several decades, they didn't originally work over long transmission lines and were superseded by telewriters and, eventually, facsimile machines. In 1886, Amos Dolbear, a Tufts University scientist and writer, was awarded a patent for a wireless tele- graph based on induction. In 1889, EG. Creed invented a High Speed Automatic Printing Telegraph System. By 1898, his Creed Printer could transmit 60 words per minute and his technology was widely sold in many countries. He broadened.his enterprise in 1923 by demonstrating marine wireless printed telegraphy, a system even- tually used for marine safety. Wireless telegraphy was ofinterest almost from the beginning oftelegraphic history. In the early 1900s, V. Poulsen and P. Pedersen used an electric arc to generate high-frequency waves, setting the ground- work for wireless communications. Poulsen also de- veloped the telegrafon, a historic electromagnetic tape recorder. Tape recorders were later used to de- velop dictation and telephone answering machines. The telegraph had a revolutionary impact on commu- nications, changing forever the concept of distance. It networked the predominantly rural early settlers of North America and spurred the installation of the first transatlantic cable, providing instant (by l800s stan- dards) communication with Europe. Prior to the oce- anic cable, messages typically took 2 months or longer to travel in ships from one continent to the 916 other. News, business, warfare, and family contacts were dramatically affected by the availability offast long distance communications. See Creed, Frederick George; heliotrope; Davy, Ed- ward; Dolbear, Amos; Morse, Samuel F.B.; Popow, Aleksandr Stepanowitsch; Salva i Campillo, Francesc; S6mmering, Samuel Thomas; Steinheil, Karl August; telegram; telegraph system; telephone; Wheatstone, Charles. telegraph key A mechanical switch on early tele- graph systems that enabled acircuit to be opened and closed in order to generate transmissions through a signal such as Morse code. telegraph signals For telegraph signals through wires, two main methods were used: polar transmis- sion, in which the polarity was changed to reverse the current; and neutral, or open/close transmission, in which open current (space) was interspersed with no current (mark). telegraph system An apparatus for sending and/or receiving information over distance, coded in some fashion, usually in Morse code dots and dashes. A basic telegraph circuit consists of a key to translate finger or other mechanical pressure into signals, a relay sensitive to the very small current that may be coming through the wire, and a receiving device which can express the message by means ofaudible tones, paper tape code, or printed letters. Telegraph systems have coexisted with, rather than been superseded by, telephone systems for a number of reasons, including the expense and time delays of setting up long distance toll calls to some areas, and the importance, in some situations, of creating awrit- ten record in the form ofa telegram. With electronic telephony advancing and facsimile machines prolif- erating, the telegraph is becoming more historically interesting than practical. See telegraph history; tele- graph, needle. Telegraph Network System A telegraph network map of the United States pub- lished ca. 1870 which shows the Pony Express Mail & Telegraph Route (in spite of the fact that the Pony Express was velY shortlived). telegraph, needle A type of five-needle telegraph devised by Charles Wheatstone and put into service in England in 1837. Faulty equipment lead to the © 2003 by CRC Press LLC gradual realization, by telegraph operators, that two needles were sufficient and, eventually, only one needle and one dial were used to efficiently convey messages. The needle telegraph also represents the development ofpolar keying, which employed posi- tive and negative voltages for indicating mark and space signals. See polar keying. telegraph, printing Early telegraph papertape and manually operated sounding systems did not satisfy the needs of inventors and users who wanted quick, automated written messages. Thus, the development of printing telegraphs was of interest to many. One of the first successful systems was developed by A. Vail in 1837, employing a type wheel. Later D. Hughes developed a practical working type wheel system in 1855, which became established in Europe, but didn't catch on well in America, where Morse systems were in use. Improvements to printing tele- graphs continued and, in 1846, R.E. House developed a printer that printed telegraphically transmitted let- ters directly. Further improvements to House's sys- tem resulted in a patent in 1852. In 1905, Donald Murray published "Setting Type by Telegraph" in the Journal of the Institute of Electrical Engineers and went on to improve telegraphy in a number of ways. The necessity of noise-free transmissions and tech- nical expertise to maintain the equipment prevented printing telegraphs from coming into widespread use until decades later. See teletypewriter. Historic Automatic Telegraph System An automatic telegraph sender. The wheels shown at the top represented characters that could be selected and placed in order to spell out a message. This ex- ample is from the American Radio Museum collec- tion. telegraphese A terse, abbreviated mode of messag- ing (or speaking) which has the character ofa tele- gram. Since telegrams were often charged by the let- ter or by the word, a compact style of communica- tion emerged in order to keep the cost as low as prac- tical. telegraphone, telegrafon This is not only a type of telegraph instrument, but more important, was an early electromagnetic tape recorder, designed in 1898 by Danish inventor Valdemar Poulsen. Poulsen suc- ceeded in recording electronic waves on a thin wire of steel, and improved on the technology enough to receive a u.S. patent in 1890. This developed into dictating machines sold through the American Tele- graphone Company. See tape recorder. TeleLink Project The full name is TeleLink Train- ing For Europe Project. This is a European Commu- nity (EC), Euroform-funded project which seeks to promote and develop telework training opportunities and qualification guidelines. This includes qualifica- tion level certification (currently at the vocational level) for teleworkers and a system of TeleLink cen- ters around Europe. See ADVANCE Project, tele- work. telemarketing The promotion of products and ser- vices through telephone calls to individual premises. There are various regulations governing when tele- marketers may call, whom they may call (e.g., calls to a person at his or her place of business must be stopped if the callee requests it), and what they must say to identify themselves and their affiliations. There are also restrictions on where they may obtain names, and how they must dial the call. Many scams have been perpetrated through telemarketing schemes, and it is important for the callee to get sufficient infor- mation to ascertain that the offering is legitimate. If you don't wish further calls from the source, you should request that your name be taken off their list. See war dialer telemarketing broadcasts The promotion of prod- ucts and services through mass market advertising usually providing a 1-800 or 1-900 number for the interested buyer to call. Automated systems for tak- ing the caller's name and billing information through touchtone selections are becoming prevalent. telemedicine Medical information and services and medical education provided over distance through telephone, radio, facsimile, videoconferencing, and the Internet. Information such as medical imaging results can readily be transferred as data, since much ofit is digital in nature. Teaching and other commu- nications among medical professionals and their pa- tients are possible through newer technologies. telemetry, telemetering The art and science of gath- ering information at one location, usually in terms of some quantity, and transmitting that information to another location for storage, analysis, or evaluation. Weather balloon data gathering and transmission through a radiosonde to a weather station for inter- pretation is one example of telemetry. The transmit- ting of information from space probes is another. Te- lemetry equipment is typically included on artificial satellites to aid in the control and orientation of the satellites. TeletextA commercial computer service offered by NBC, which was discontinued in 1985. Many of these early computer services came and went, but they are coming back in updated forms now that there is a large user base drawn to the Web. telephone A communications apparatus designed primarily to convey human voice communications. In its simplest form, a telephone consists of a tran- sistor that converts sound into electrical impulses, and 917 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary a receiver, which converts them back again into sound. Additional technology is used to amplify and direct the communication between these two basic de- vices. The design of the telephone set has gone through five overlapping phases in its development. See the Telephone Development Phases chart. See telephone history. Historic Telephone The earliest telephone was a simple device that looked more like a pinhole camera than current fa- miliar desktop phones and mobile handsetphones. telephone amplifier A device to amplify sounds at the receiving end ofa call. This can be incorporated into the handset, headset, or speakerphone, or may be an add-on to provide even more amplification for the hard of hearing. Most handset telephone amplifi- ers draw current from the phone line, but many speakerphones and add-on amplifiers require a sepa- rate power source. The amplifier is often adjustable through a dial or slider on the side of the phone. telephone answering machine An electronic or me- chanical device for answering calls and often for re- cording them digitally or on tape. Telephone answer- ing machines based on reel-to-reel mechanisms have been available since the early 1960s, but small cas- sette and digital answering machines did not become common until the late 1970s and early 1980s. Most households now have answering machines to respond to calls, take messages, or screen calls. Many of these will include information on the time and date of the call, and some will record the identity of the caller, if Caller ill is activated on the subscriber line. Computer voicemail applications can also be hooked to a phone line through a data/fax/voice modem to allow the software to function as a full-featured an- swering machine with multiple mailboxes. telephone answering service 1. A service offered by commercial vendors in which a human operator or voice-automated system will answer the subscriber's phone line when it is call fOIWarded, or when the an- swering service number is called directly and for- wards the message to the subscriber. This service is widely used by small businesses, freelancers, and real estate agents. Sometimes these services are combined with paging. 2. A service offered by local phone com- panies in which a human operator or voice-automated 918 system will take calls and fOIWard messages to the subscriber, or through which the subscriber can use a touchtone phone to retrieve messages. telephone central office See central office. telephone circuit An electrical connection consist- ing minimally ofa transmitter, receiver, amplifier, and connecting wires, and more commonly comprising a system of two-way audio and signaling connections between local exchanges and subscriber lines and telephones. Telephone Company of Prince Edward Island A historic telephone exchange, incorporated in 1885, the year after the phone exchange was first established on the island. telephone exchange Switching center for telephone circuits. See central office, private branch exchange. Innovative Optical Telephone An innovative optic telephone, based on the stimu- lation through a diaphragm of aflamefrom an acety- lene burner. The impulses were thenfurther transmit- ted optically through a light-sensitive selenium cell and reflector. The optic telephone was developed by Ernst Ruhmer, and was used for long distance com- munications. [Scientific American, November 1, 1902.} telephone history The telephone was a significant evolutionary development, occurring a few decades after the invention of the telegraph. While the tele- graph revolutionized telecommunications by making communications over great distances possible, the telephone personalized it, and many inventors were excited by the potential of sending tones, or even voice, over phone lines. The use of tubes and strings to magnify sound and channel acoustic vibrations existed at least as early as the time of Robert Hooke, long before the devel- opment of modem telephones, but such devices, like the acoustic tubes demonstrated in 1682 by Dom Gauthey, were physically limited as to loudness and distance. It was not until electricity and magnetism were harnessed that amplified, long-distance modem telephony was possible. In the early 1800s, German inventor Philip Reis ob- served that a magnetized iron bar could be made to © 2003 by CRC Press LLC emit sound. In America, Charles Page made a similar discovery, terming the sound "galvanic music." Sub- sequently, a number of inventors advanced tele- graphic and microphonic technologies leading up to the invention of the telephone. Belgian inventor Charles Bourseul described his idea for transmitting tones in 1854, but wasn't able to implement a fully working version before Philip Reis and Alexander Graham Bell developed their own telephonic devices. Reis first demonstrated the transmission of tones through wire in Frankfurt in 1861. He reported in a letter that he could transmit words, but there is no direct way to verify the claim. Around the time ofReis's death, an American physi- cist, Elisha Gray, was making numerous experiments in telegraphy and developed early concepts for har- monic telegraphy, the transmission of tones, and te- lephony. In the mid-1800s, Italian-born Antonia Meucci was successfully experimenting with wires attached to animal membranes to transfer sound through current, but news of his significant discoveries did not become widely known outside Cuba. When he later emigrated to the U.S., he filed a caveat for a patent, in Decem- ber 1871, for a teletrofono. Bell's Telephone Demonstration Here Alexander Graham Belldemonstrates his tele- phone invention. The inset shows one of his early sketches of the invention, from the famous Bell note- books. Bellachievedgreatfinancial success from com- mercializing his discoveries. The better-known precursors to the telephone in America and later variations appear to have been in- vented more-or-Iess independently by Elisha Gray and Alexander Graham Bell, but Bell filed his tele- phone patent (it was actually a precursor to the tele- phone, a hannonic telegraph) a few hours before Gray filed a caveat (intention to file within 3 months) in February 1876. The murky history of the invention of the telephone at this point stems in part from the fact that many innovations were being developed si- multaneously and also because the inventors under- stood the great commercial potential of their devices. Hundreds of lawsuits were threatened and filed over the next few decades, although some claims were more amicably settled. For example, in January 1877, Bell wrote to Gray rescinding any previous accusa- tions he may have made that Gray copied from Bell's work. (In fact, both men may have copied from a third source, Antonia Meucci. It has been suggested, but not confirmed, that both Bell and Gray had access to Meucci's teletrofono documents when they were in the hands of Western Union.) Emil Berliner was an inventor with a strong interest in music and the improvement of the quality of transmission of sound (which applied equally well to telephony). In April 1877, he filed a caveat for a patent for a telephone transmitter, three and a half months before Thomas Edison applied for a patent for a similar device. In a 1911 lecture on the origins of the membrane tele- phone, Bell described how he worked out the idea in discussions with his father while on a family visit in Canada in the summer of1874,2 years before it was successfully implemented. Bell and Watson reported that Bell first spoke intelligibly over wires in March 1876. The transmission succeeded by use ofa liquid medium, something not mentioned in Bell's patent. This voice capability was not publicly demonstrated until some time later, which seems odd given the magnitude of the reported achievement. Ironically, Bell had been discouraged by investors from trying to make a talking telegraph and was prodded to con- centrate on a harmonic telegraph instead. Gray had publicly demonstrated rudimentary tele- phone-related technology before the Bell patent was filed, and later successfully earned a number of tele- phone-related patents. He designed a telephone in the 1870s not unlike the second-generation switch-hook phones that employed separate ear and mouth pieces which came into use in later years. The first commercial telephone exchange was estab- lished in Connecticut, U.S., and became operational in 1878. It was followed the same year by the second commercial exchange in Ontario, Canada. The Bell patents formed the basis of the early Bell System in the United States, a company that has in- fluenced the development of communications, and thus the course of history, in countless important ways. The Bell Telephone Company of Canada was incorporated in 1880. By this time, telephone technology began to spread to other nations outside Europe and North America. The first telephone exchange was established in Ja- pan in 1890 in the TokyoNokohama region. In 1926, automatic step-by-step switches were introduced in Japan. The most interesting evolutionary step in telephone technology, besides the growth of wireless commu- nications, is probably the videophone, descended from early picture telephones such as the Picture- phone. The Bell Labs were transmitting pictures in the late 1920s and demonstrated the early technol- ogy to the Institute of Radio Engineers in 1956, but it was not until 1964 that a practical experimental system was completed and the Picturephone was 919 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary exhibited cooperatively by Bell and the American Telephone and Telegraph Company (AT&T) at the New York World's Fair. Currently many companies are scrambling to be the first to get a cheap, publicly accepted version ofa pic- ture telephone or as they are known now, audiograph- ics systems, videophones, or videoconferencing sys- tems. With the growth of the Internet and the drop in price of small video cameras, they began to be com- mon computer peripherals in 2002. Another significant change in telephony has been the sending of voice over computer networks by means ofa specialized handset attached to a computer. This permits the connection of long distance calls world round without any long distance toll fees. The tech- nology threatens to dramatically change the estab- lished economic structure of the telephone system, and it is difficult to predict whether the same revenue- generating model that has worked for about 100 years will be viable in the future, given the current rate of change. In fact, some of the long distance carriers, worried by this threat to their survival, have lobbied for this type oftransmission to be blocked. See Bell, Alexander Graham; Berliner, Emil; Bourseul, Charles; Callender switch; Gray, Elisha; Meucci, Antonio; Photophone; Reis, Philip. See telegraph his- tory which has a common ancestry and additional details. telephone landline density A measure of the num- ber of installed phone lines per 100 people. telephone pickup Any of several devices for con- necting into an ongoing telephone conversation, usu- ally for monitoring purposes. Telephone Pioneers of America TPA. A nonprofit organization founded in 1911, with chapters through- out the United States and Canada. Originally consist- ing of telephone pioneers with 25 years ofservice or more, with Theodore N. Vail as its first president, membership later opened up to a wider group, now numbering almost 100,000, as fewer pioneers re- mained from the original group. TPA engages in a number of community-oriented activities, with a particular focus on education. A somewhat analogous organization serving non-Bell employees is the Independent Pioneers. http://www.telephone-pioneers.org/ telephone receiver The portion ofa handset, head- set, or speakerphone which converts electrical impulses into sound. On a handset, the receiver is the part that you hold up to your ear. Inside a basic tradi- tional receiver is a magnet, with coils wound around the poles connected in series and a light, thin, vibrat- ing diaphragm mounted very close to the magnet poles. When current passes through the coils, the dia- phragm vibrates, producing sound by moving the air next to it. Early receivers used a bar magnet, which later was replaced by a horseshoe magnet. See tele- phone transmitter. Telephone Relay Service A telephone service en- abling handicapped individuals to communicate over telephones through third party interpreters. It is usu- ally provided free of charge. telephone repeater An amplification device em- ployed on telephone circuits to rebuild and maintain signals across distances, which otherwise would be subject to loss. telephone signaling Any device that indicates an in- coming call, usually a bell, but may also be a light or moving indicator. telephone switchboard A centralized distribution point for managing telephone calls. Early switch- boards consisted ofa human operator answering calls, and plugging a large physical jack into the receptacle of the person to whom the call was being patched. The first commercial switchboard in North America Overview of Telephone Development Phases Type Time period Notes original invention late l800s Proof of concept, tbe first discernible, intelligible buman voices can be heard over distances. hand crank pbones late 1800s, early 1900s Pbones were large, to accommodate a battery, and had to be cranked to send a ringing current. Hand-crank phones were still in use in rural areas, including some of the San Juan Islands in the 1960s. dial phones early 1900s to 1980s Common batteries and automatic switching systems made it possible to create smaller, line-powered phones and rotary dials so the subscriber could direct dial a local call, and later, long-distance calls. touch tone phones late 1970s to present Phones that sent tones rather than pulses through the line, which were interpreted according to pitch. This made automated menu-controlled systems possible. digital phones early 1990s to present Interface speakers or beadset peripherals that attach directly to a computing device or desktop system to enable the user to talk into a digitizing program that samples the sound and transmits it over public data networks. 920 © 2003 by CRC Press LLC Semiautomatic Telephone Switching System went into operation in Connecticut in 1878. Switches were mechanized in the mid-1900s, although it was not uncommon for human switchboard operators to staff manual switchboards in rural areas and private branches until the 1950s. Although mechanical switchin~ stations still exist, updated switchboards function electronically. telephone tag Colloquial phrase for two parties at- tempting to contact one another by phone, not reaching the other person, and leaving messages with an answering machine, operator, or voice mail system. Doing this back and forth a few times is telephone tag. telephone transmitter The portion of a handset, headset, or speakerphone which converts sound into electrical impulses. On a traditional handset, the re- ceiver circuit connects to the part that you hold next to your mouth. Inside the mouthpiece is a movable diaphragm with an attached carbon electrode, behind which another carbon electrode is fastened securely inside the housing. Between the electrodes are car- bon granules (it's possible to build a simple phone transmitter using the core of a carbon pencil laid across two conducting surfaces connected to wires and a diaphragm). When a current is applied, resis- tance decreases, as a result of the carbon granules compressing more closely together. Thus the current increases and attracts the diaphragm more strongly. The diaphragm vibrates to produce an electrical im- pulse that corresponds to the movement of air caused by the speaker's voice. An induction coil may also be used to increase the voltage to compensate for sig- nalloss through the transmissions medium. See Blake transmitter, coherer, telephone, telephone receiver. telephone user interface TUI. The use of telephone equipment, usually a handset or headset or telephone line attached to a peripheral card, to interact with computer software. Instead of using a keyboard and mouse as the input devices, voice or touchtones over the handset or phone line are used to control the ac- tions of the computer. For example, you may have a computer set up like an answering machine to answer calls, respond to callers, and log time, date, and caller messages. Then, from a remote location, you may call the line attached to the computer, and by speaking or pressing touchtone buttons, have the computer send back information about the calls or replay the calls. telephony The science and practice of transmitting audio communications over distance, that is, over a greater distance than these communications could be transmitted without technological aid. The term has broadened from audio communications to encompass a wide variety of media, typically now including vi- sual communications that accompany sound commu- nications (as in audiographics and videoconferenc- ing), although it is preferred that the more general term telecommunication be used for audio/visual transmissions. Most telephony occurs over wires, but wireless services transmitted by radio waves and sat- ellite links are increasing. I Telephony, in its simplest sense, is not a high band- width application; each conversation requires only a narrow channel, but because of its continuous bidi- rectional nature, bandwidth needs increase as the number of simultaneous calls increases. Traditional telephony media, such as copper wires, are no longer strictly used for oral communications; they now ser- vice a large number of data transmission services such as Internet connectivity, facsimile transmission, and more. Due to increased demands for lines with greater speed and accuracy than are needed for simple voice transmissions, fiber and coaxial technologies are be- ing used to upgrade data lines and, consequently, the phone lines. See HFC, telephone, telegraph. Telephony Application Interface TAP!. A standard- ized telephone interface developed by Microsoft and Intel Corporation for the creation of a variety of A schematic for a historic semiautomatic telephone switching system (it still required a human operator to turn a spring-loaded knob to send the dialpulses through the wire). [Scientific American, October 11, 1902.] 921 © 2003 by CRC Press LLC . metallic TIA Fiber Optic Communication Standards Document Designation Description TWEIA-45 5-1 64A FOTP-I64 TIAlEIA-45 5-1 71A FOTP-171A TWEIA-45 5-1 91A FOTP-191 TIA-52 6-2 OFSTP-2 FOTP-5 FOTP-78 100 Mbps FOTP-87 FOTP-98 FOTP-157 Humidity Test Procedure for Fiber Optic Components Spectral Attenuation Cutback Measurement for Single-Mode Optical Fibers Fiber Optic Cable Knot Test Fiber Optic Cable External Freezing Test Measurement of Polarization Dependent Loss (PDL) of Single-Mode Fiber Optic Components Single-Mode Fiber, Measurment of Mode Field. Diameter by Far-Field Scanning Attenuation by Substitution Measurement for Short-Length Multimode Graded-Index and Single-Mode Optical Fiber Cable Assemblies Measurement of Mode Field Diameter of Single-Mode Optical Fiber Effective Transmitter Output Power Coupled into Single-Mode Fiber Optic Cable Single-Mode Fiber Optic System Transmission Design Fiber Optic Connector Intermateability Standards Blank Detail Specification for Single-Mode Fiber Optic Branching Devices for Outside Plant Applications Physical Layer Medium-Dependent Sub layer and 10 Mbps Auto- Negotiation on 850 om Fiber Optics Relevant Technical Committees TIAlEIA-45 5-8 7B TWEIA-45 5-9 8A TIAlEIA-45 5-1 57 TIAlEIA-45 5-5 B TIAlEIA-45 5-7 8A TIA-559 TWEIA-604 TWEIA-620AAOO TIAlEIA-785 FO-2.l Single Mode Optical Communication Systems FO-2.2 Digital Multimode Systems FO-2.3 Optoelectronic Sources, Detectors, and Devices FO-2.6 Reliability ofFiber Optic Systems & Active Optical Components FO-6.1 Fiber Optic Field Tooling & Instrumentation FO-6.2 FO-6.3 FO-6.6 FO-6.7 FO-6.9 Terminology, Defmitions, & Symbology Interconnecting Devices and Passive Products Fibers and Materials Optical Cables Polarization-Maintaining Fibers, Connectors, and Components 912 ©. Committees TIAlEIA-45 5-8 7B TWEIA-45 5-9 8A TIAlEIA-45 5-1 57 TIAlEIA-45 5-5 B TIAlEIA-45 5-7 8A TIA-559 TWEIA-604 TWEIA-620AAOO TIAlEIA-785 FO-2.l Single Mode Optical Communication Systems FO-2.2 Digital Multimode Systems FO-2.3 Optoelectronic Sources, Detectors, and Devices FO-2.6 Reliability ofFiber Optic Systems & Active Optical Components FO-6.1 Fiber Optic Field Tooling & Instrumentation FO-6.2 FO-6.3 FO-6.6 FO-6.7 FO-6.9 Terminology, Defmitions, & Symbology Interconnecting Devices and Passive Products Fibers and Materials Optical Cables Polarization-Maintaining Fibers, Connectors, and Components 912 ©