Fiber Optics Illustrated Dictionary - Part 32 pptx

Fiber Optics Illustrated Dictionary around the equator at 2000 kilometers using CDMA in the i-iS-band frequencies for down/uplink transmissions, and C- or Ku-band for feeders. The target service area is the equatorial belt between 23 ° north and south latitudes, comprising over 75 countries and a high proportion of the world's population. In spite of the large number of people who live in this region overall, many of them are in remote, small, rural communities with few or no wired communications services. From the user's point of view, ECO-8 telephony services are functionally similar to cellular. The caller's desired number is transmitted through the satellite system to the local gateway where it is further relayed to a public phone circuit, wireless system, or to another ECCO satellite to link with another subscriber. ECCO Working Group European Chapter on Com- binatorial Optimization. This is a EURO Working Group that discusses recent and important issues in combinatorial optimization, founded in 1987. echelle grating (Fr. - echelle meaning ladder) A high- resolution, stepped (blazed) optical grating structure used as a wavelength conditioner in certain spectrom- eters, telescopes, and optical communications components. Aluminum is commonly used as a coating on the grating to provide the reflective surface and there may be an additional coating to prevent corro- sion of the aluminum. An echelle grating has a broader groove than an echelette grating and thus fewer grooves over a specified length. It is used in near-iittrow, high reflection angles in high diffraction orders. In general, light is reflected from a collimated light source or reflecting mirror onto the blazed steps of the echelle grating where it selectively reflects off the angled surfaces of the grating to a detector or intermediary component such as a cross-dispersion grating. Since the orders overlap, practical embodiments of echelle gratings in optical systems may include additional ele- ments to optically separate these orders (e.g., ~ prism as shown in the accompanying diagram). Echelle gratings have the advantage of being compact, while still providing relatively high resolution. They also affect a fairly wide spectrum of frequencies. There have been a number of patents for fiber optic communication technologies incorporating gratings to support dense wavelength division multiplexing (DWDM). Bragg gratings have been cited in many of these. In July 2000, A. Sappey and G. Murphy sub- mitted a patent application for a dense wavelength multiplexer/demultiplexer for propagating multiple optical channels with a select channel spacing as a single optical signal in the near-infrared range, using an echelle grating optically coupled to the collimating/focusing component. A practical embodiment of the Sappey/Murphy invention would incorporate an echelle grating with a resolution of at least 20,000, with between about 50 to 300 grooves/mm, a blaze angle between 51 and 53°, and a free spectral range at least as large as the near-infrared frequency range to yield a multiplexed channel spacing of 0.4 DIn or less with a separation 302 of at least 40 IJ See diagram. See blazed grating. echellette grating Similar in structure and function to an echelle grating, except that the reflection angles may be lower and the grating period finer. Echellettes are associated with different dispersion characteris- tics compared to echelle gratings. The pattern of dispersed wavelengths tends to be slightly broader for an echellette grating, with less overlap of the orders than is found in echelle grating dispersion. For detection instruments, it is useful to be able to switch between echelle and echellette grating reflectors in order to view the light phenomena from a slightly different statistical point of view. echo 1. Repetition ofa sound (or other reflective phenomenon) due to reflection, with the echo gradually dying away through attenuation. Undesirable echo is sometimes experienced on phone lines and radio links where there is a delay or other technical problem. Deliberately induced echo may be used as a testing strategy and is intrinsic to reflected signal detection schemes such as sonar and radar. 2. Output to a command line or output window on a computer. Echo is a command used by many batch and other scripting languages to echo or print to a terminal, whether that terminal is a window on a computer screen, a tele- type, or a printer. ECHO European Commission Host Organisation. A noncommercial network host gateway to support and promote the use of network information services within the European Community (EC), established in 1980 by DG XIII/E. It is now managed by the In- formation Market Policy Actions (IMPACT) program. ECHO provides a means for businesses to understand the use and benefits of multilingual database information services. It provides a demonstration host, training, online access to directories of electronic information services, and a means to intercommunicate with associated individuals and orga- nizations. ECHO 1A telecommunications and geodesic satellite launched into an orbit of 1600 Ian by the u.S. on August 12, 1960. ECHO 1 is historically important because it provided the first government sateHi te telephone links and television broadcasts on February 24, 1962. This satellite's orbit decayed in 1968. See ANIK for information on the first commercial television broadcast. echo cancellation A technique for isolating and fil- tering unwanted echo signals which may accompany and interfere with the main analog transmission. Echo cancellation is often used on voice circuits, especially satellite transmissions, and may also be used in frame relay systems. In general, echo cancellation attempts to maintain a full-duplex circuit, although there are exceptions as in clear channel or ISDN calls. See echo suppressor, interference, noise. echo check A diagnostic technique in which data is transmitted and then echoed back from the receiving end to the sender to check the completeness and in- tegrity of the data. ECHO satellites A series of satellites launched by the United States, beginning in 1960. The early © 2003 by CRC Press LLC ECHO Project launched large highly reflective bal- loons capable of bouncing back radio signals. With- out active relays, the communications signals were weak, but much was learned from these early experi- ments. The series included ECHO A-IO (never achieved orbit), ECHO 1, ECHO 2 (delayed from 1962 to 1964). Improvements in active relays superseded the ECHO Project. See ECHO 1, West Ford satellites. echo suppression A means of reducing undesirable echoes, especially in satellite voice communications. Echo suppression differs from echo cancellation, in that echo suppression disables the reverse transmission while the person continues to talk, thus function- ing more like a half-duplex line. See echo cancellation, interference, noise. echo suppression disabler A means to coordinate echo suppression, the removal of undesirable echoes, especially on satellite voice lines. Since echo suppres- sors limit the capability of the system to half-duplex transmission by suppressing the signal in the direction opposite to the sending signal, it is important to be able to disable the echo suppression to restore full- duplex operation. Echo suppression is typically dis- abled by sending a high-pitched signaling tone from an answering modem. Eel 1. equipment catalog item. 2. End Chain Indi- cator. A boolean indicator signifying the end of a chain of data. In Systems Network Architecture (SNA) systems, it is contained in the sna.rh.eci field. 3. engineering change instruction. 4. external call interface. Generically, a hardware and/or software means to intercommunicate with a local or internal system and an outside or external system, as between a local network and the Internet or between a private branch exchange (PBX) and a public switched Echelle Grating Incorporated into DWDM Multimode Optical Communications System This diagram illustrates the basic components assembled with an echelle grating in a D WDM system. A pigtail harness (left) supports thestructural output of multiple waveguides. Lightpasses through a collimating/focusinglens (18) that is optically coupled to the echelle grating (20). The grating subdivides the incident light beam containing multiple channels and angularly disperses the output wavelengths with good spatial and channel separation. The schematic on the left is a closeup cross-section of the echellegrating, illustrating the incidentlight interacting with the blazed grating structure. The riser (a) and reflective step (b) combine to form a grating period. In this DWDM embodiment, the system would have a groove density of<300 grooves/mm and a blaze angle (8J >45 0 to efficiently separate closely-spaced channels within a reasonbly compact area. The schematic on the right illustrates the basic components of an echelle grating multiplexer/demultiplexer. Light from a single-mode optical fiber (62) is reflectedto theprism (68) by the collimating/focusing mi1Tor (64). The two- dimensionally dispersed wavelengthsfrom theprism reflect off the echellegrating (72) and are directed to a concave collimating/focusingmirror (74) which then directs thebeams towardan outputfiber array (76). [Sappey andMurphy; U.S. patent #6,415,080, July 2002.] 303 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary telephone network (pSTN). 5. External Call Interface. On a CICS system, an application programming interface (API) that enables a non-CICS client program to communicate with a CICS program, calling it from a CICS server. Thus, the client can access server rou- tines such as utilities and databases. ECIS 1. European Committee for Interoperable Sys- tems. 2. European Computer Industry Research Cen- tre 3. European Conference on Information Systems. 4. European Council of International Schools. Eckert, John Presper (1919-1995) An electronics inventor and collaborator with 1. Mauchly on the historic ENIAC computer project. With Mauchly, he formed the Eckert-Mauchly Computer Corporation in 1946, which was acquired by Remington Rand Corporation in 1950. When Remington Rand merged with Sperry Corporation in 1955 to form Sperry Rand, Eckert became an executive with the company. The firm eventually merged with Burroughs Corpo- ration to become Unisys. See BINAC, ENIAC. ECL See emitter-coupled logic. ECMA See European Computer Manufacturers As- sociation. ECMATC32A project of the Standardizing Informa- tion and Communications Systems Technical Com- mittee of the European Telecommunications Stan- dards Institute jointly with ECMA, an international standards association, with a working agreement between the two bodies signed in September 2000. ECMATC32 working groups include TG 14, for private integrated services and corporate network services and signaling, and TG 17, for corporate open architecture and systems for IP-based services. Thus, the focus of the standardization efforts is private and corporate telecommunications systems. ECN See explicit congestion notification. ECOMEG See E-commerce Experts Group. ECP 1. electronic commerce platfonn. 2. See Encryp- tion Control Protocol. 3. See Enhanced Call Process- ing. 4. See Executive Cellular Processor. ECPA See Electronic Communications Privacy Act of 1986. ECSA See Exchange Carriers Standards Association. ECT explicit call transfer (e.g., as in ISDN Q.82 or Q.732 call offering services). ECTRA European Committee for Telecommunica- tions Regulatory Affairs. ECTUA See European Council ofTelecommunica- tion Users Associations. ECTEL See European Telecommunications and Pro- fessional Electronics Industry. ECTF 1. See Enterprise Computer Telephony Forum. 2. See European Community Telework Forum. ECTUA See European Council ofTelecommunica- tions Users Association. EDAC error detection and correction. EDACS See Enhanced Digital Access Communica- tions System. EDDA See European Digital Dealers Association. eddy current An electrical current induced by an alternating magnetic field, which can be found in good conductors such as iron and may contribute to signal 304 loss in electrical circuits. EDF erbium-doped fiber. See erbium doping. EDFA See erbium-doped fiber amplifier. edge connectorA common type of thin, printed circuit board foil-imprinted extension used for making an electrical connection to a slot, usually inside a computer or in a peripheral card bay. edge-emitting A component that emits acoustic or electromagnetic waves through the structural or func- tional side of the component. For example, in semiconductor laser diodes, which are fabricated in lay- ers, the laser emission is from the side and thus each individual component must be stamped out before it can be tested. See vertical-cavity surface-emitting laser. EDH See electronic document handling. EDI See Electronic Data Interchange. EDIFACT, UN/EDIFACT Electronic Data Inter- change for Administration, Commerce and Transport. Arising out of work by ANSI and the United Nations, EDIF ACT was developed during the 1970s and 1980s by the United Nations Working Party on Facilitation of International Trade Procedures to provide a standardized means to facilitate data exchange. EDIF ACT provides internationally agreed-upon standards for platform-independent directories, syntax, and struc- tures for character- fonnat electronic documents. The transmission of EDIF ACT documents involves the creation ofa flat file (e.g., through export from a compatible application such as a word processing program) that is passed to an EDIFACT translator where it is converted to an EDIFACT Message following the U.N. guidelines. The file, which includes routing and destination information, is sent over the network and, when it reaches the destination, is de- coded according to the type of Message sent and stored or imported to a compatible application. EDIFACT conventions are published by the United Nations in their Trade Data Interchange Directory (UNTDID). See Electronic Data Interchange, Trade Data Interchange. EDIS See Emergency Digital Information System! Service. . Edison base The standard screw-in light bulb base common in North America. Edison cellA historic variable-storage nickel hydrate (positive) and iron oxide (negative) battery cell with an electromotive force lower than that ofa lead cell (about 1.2 volts). It was developed by Thomas Edi- son and became suitable for use in automobiles due to its ruggedness. See battery for a chart of other types of cells. Edison effect A phenomenon that Thomas Edison observed in 1883 and patented in 1884. While working with electrical illumination, he sealed a metal wire into a bulb near the filament and noticed that electricity flowed across the gap between the hot filament and the metal wire, a discovery that became important to later electronic researchers in the deve10pment of broadcast technologies. See Audion. Edison Electric Institute EEL A professional association supporting U.S. shareholder-owned electric © 2003 by CRC Press LLC utility companies and their affiliates and associates worldwide. Members service about 70% of the U.S. electric customer base. The EEl advocates public policies and provides strategic business and market- ing support. http://www.eei.org/ Edison General ElectricA company formed by thomas Edison in 1889. Throughout his prolific career, Edison sought practical, commercially viable applications of his ideas, and he actively marketed many of the products that were invented in his laboratory. Thomas Alva Edison - Prolific Inventor Thomas Alva Edison was a significant inventor of audio recording and playing technologies. [U.S. Na- tional Archives collection.] Edison, Thomas Alva (1841-1931) An American inventor who, at the age of 15, learned telegraphy and soon became a very fast and competent telegrapher. In 1868, he invented a device to record votes, and later, in New York, invented a stock ticker. In 1876, he set up a pioneer industrial research lab in Menlo Park, New Jersey, where he turned out hundreds of inventions, including the phonograph, electric type- writer, and fluoroscope. He developed the ideas of others, as well, making practical improvements to Bell's early telephone devices. Edison's inventive output was prodigious, and he pursued his interests almost to the complete exclu- sion of his business affairs, practical matters, and family. In all, he received more than 1000 patents. Edison is probably best remembered for developing the incandescent lamp in 1879, following the invention of the arc lamp by Humphry Davy early in the century and a short-life incandescent bulb by Joseph Wilson Swan. His efforts were aided, in part, by the earlier research of M.G. Farmer, who supplied him with advice and a number of materials that might be useful in building a lamp. Almost immediately following his historic invention, Edison began an electrical utility company in New York City, in 1882, called the Pearl Street Central Station. This and other early utility companies provided direct current (DC) which has since been almost universally superseded by alternating current (AC), an approach promoted by Nikola Tesla and denounced by Edison. See Farmer, Moses; incandescent lamp; Tesla, Nikola. editor A software program for manipulating information, particularly textual information. While graphics can be edited online, the tools to do so are not usually called editors, but rather paint or drawing programs or image processors. The term editing is used more in the context ofline-oriented information car- ried out with word processors, desktop publishing programs, and text editors. Programming editors are often optimized for the special formatting needs of programmers. For example, they may monitor parenthetical statements and alert the programmer if the parentheses or brackets are unbalanced, which would result in a syntax error in the program. They may provide different colors for different kinds of information, as for comments, variable names, or procedural labels. They may also provide the capability of telescoping or expanding the text (a feature also found in some word processors). Scriptwriting editors are often set up with templates that indicate the correct margins and line spacing required by the theater and motion picture industries. Word processors are optimized for document creation and basic formatting of text. Extensive formatting of text and graphics shouldn't be done with a word processor. Yes, it's possible, and yes, individuals have created some great documents with word processors, but it's also possible to hammer with the backside of a hatchet. It just isn't very efficient or comfortable. Complex page layout should be done with a page layout program. In a business environment, the extra cost of the software is incidental compared to the extra hours, weeks, or months that have to be paid to some- one to use a word processor for an unintended purpose. GNU-Emacs is one of the most powerful text editors in existence, developed by Richard Stallman in the mid-1980s. It is configurable, scriptable, full-fea- tured, and freely distributable. EDM electronic document management. Edmund Industrial Optics A New Jersey-based designer and manufacturer of optical solutions for electronic imaging, biomedical and biometric applications, telecommunications, and semiconductor industries. Affiliated with Edmund Scientific, it is an international supplier of industrial optical components and devices, including coatings, lenses, illumi- nators, lasers, etc. Edmund Scientific A significant supplier of scientific professional and hobbyist lab supplies and optical and robotics components. If you like cool techie toys and great science projects, this company has a wide variety of interesting products. EDO RAM extended data-out random access memory. A type of faster random access memory (RAM) that began to become prevalent around 1997. Many Intel-based desktop architectures were de- signed with expansion slots for EDD RAM, as it was less expensive than previous types of RAM. 305 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary EDP See electronic data processing. EDRS European Data Relay Satellite. See European Space Agency. EDSAC Electronic Delay Storage Automatic Com- puter. A historic large-scale, stored-program, electronic, digital computing machine developed in 1949 at Cambridge University, England, under the leader- ship of Maurice Wilkes. See EDVAC, ENIAC. EDTV See enhanced-definition TV. EDVAC Vacuum-Tube Computer Running the room-sized ED VA C required staff to operate and maintain hundreds of vacuum tubes and thousands of feet of wires. Modern handheld desktop calculators are now faster and more powerful. {US. Army photo.] Educational Technology Branch ETB. A branch of the Lister Hill National Center for Biomedical Com- munications that conducts research and development in computer and multimedia technologies and dis- seminates the information to the u.s. National Li- brary of Medicine, the world's largest biomedicalli- brary, which is located in Bethesda, MD. http://lhncbc.nlm.nih.gov/ http://www.nlm.nih.gov/ EDUCAUSE A consolidation of CAUSE and Educom, established in July 1998, EDUCAUSE is an international, nonprofit association. EDUCAUSE administrates an extensive collection of higher education information technology (IT) resources for higher education institutions and firms supporting the higher education information technology fields. EDUCAUSE supports and participates in advocacy projects, conferences, and seminars and other professional development activities. It is affiliated with various higher education and computing associations throughout North America. See CAUSE, Educom. http://www.educause.edu/ Educom An association of colleges and universities dedicated to the support and evolution of educational computer network technologies. In July 1998, Educom was consolidated with CAUSE to form EDUCAUSE. See EDUCAUSE. 306 EEC European Economic Community. Now the Eu- ropean Union (EU). A European common market that has been in development for several decades. Gradu- ally, European currency, European passports, inter- country networks, and greatly reduced border restric- tions are being phased in. See European Union. EEl 1. See Edison Electric Institute. 2. external en- gine interface. 3. See external environment interface. 4. See External Environment Interface. EES Earth exploration satellite. EEMA See European Electronic Messaging Associa- tion. EEPROM electronically erasable programmable read-only memory. See erasable programmable read only memory. EF &1 engineer, furnish, and install. EFCI See explicit forward congestion indicator. EFF See Electronic Frontier Foundation. effective competition A market regulation status level. Broadcast cable providers must meet certain criteria to claim effective competition status. See cable access. effective radiated power ERP. The transmitting power ofa broadcasting antenna. It is sometimes controlled by a directional antenna. EFI&T engineer, furnish, install, and test. EFS 1. See electronic filing system. 2. See Electronic Filing System. 3. electronic financial system. 4. See Electronic Form System. 5. See error-free seconds. EFT See electronic funds transfer. EFTA See European Free Trade Association. EG See European Graphics Association. EGA See Enhanced Graphics Adapter. EGC 1. Economic Growth Center. Astatistical and economic development archive at Yale University. 2. See Enhanced Group Call. Eggebrecht,Lew Chiefof Commodore Engineering at about the time Commodore-Amiga was sold to Amiga Technologies in Germany. See Amiga. EGNOS European Geostationary Navigation Over- lay Service. A European land and marine communications service which augments the U.S. Global Po- sitioning System (GPS) and the Russian GLONASS system (similar to U.s. GPS), using the raw data to compute information and broadcast it through the GEO satellites. The EGNOS system combines ground-based and satellite segments to comprise the European implementation of the Global Navigation Satellite System (GNSS). See Global Navigation Satellite System, Wide-Area Augmentation Service. ego surfing slang Searching for your own name on the Net, in the media, or in databases. There are many legitimate reasons for ego surfing, and everyone should probably do it once in a while to make sure names or net addresses are not fraudulently distributed or used by imposters to post to newsgroups. Such misuse could result in misunderstandings and embar- rassment (and sometimes even litigation) directed at the legitimate owner of the name or address. There are search engines on the Internet that allow © 2003 by CRC Press LLC users to check newsgroups for postings under a par- ticular name. Many Web directory services on the Web give out phone, address, and sometimes even personal information on individuals, drawn from phone books and less legitimate sources. You must alert these services if your personal statistics are being used indiscreetly or illegally and request that they stop. (There is usually information about you on the Net, whether or not you even use a computer.) Ego surfing is routinely engaged in by those who enj oy studying family histories and are on the look- out for more information to add to their genealogy databases. Ego surfing also can help those who are publishing scientific, political, or other information with wider social implications to follow the dissemi- nation, and sometimes the impact, of their communications, in order to engage in global dialog or to correct misrepresentations or misunderstandings. EGP See Exterior Gateway Protocol. egress 1. Exit, way out. 2. In frame relay networks, frames that are exiting away from the frame relay to- wards the destination. The opposite of ingress. EIA See Electronic Industries Alliance. EIAInterface StandardsA collection of standards describing configurations, signals, and other communications parameters for various electronic connecting interfaces. These are often used in conjunction with ITU- T specifications for protocols and functions. Probably most familiar of the Interface Standards are EIA-232-D and EIAffIA-232-E, which are 1987 and 1991 updates to the decades-old RS-232 specification for serial transmissions between data terminal equipment (DTE) and data communications equipment (DCE). This standard has been widely imple- mented in desktop computers and other devices and is commonly used for communicating with modems, remote terminals, and printers. Most systems support EIA-232-D and EIA!fIA-232- E through 25-pin D connectors, though minimally nine pins are needed to implement the specification, and 9-pin D connectors (EIA-574) are sometimes used. The EIA has also defined faster standards for serial communications, including EIA-422 (balanced signals), EIA-423 (unbalanced), EIA-485 (multi- point), and EIA-530 (EIA-422 with 25-pin D con- nector). EIA standards additionally encompass wiring connectors and topology, including building wiring and network backbones. EIAITIA categories Standardized specifications for cable transmission speeds. See the EWTIA Trans- missions chart for categories. EICTA See European Information and Communica- tions Technology Association. EIG See Electronic Information Group. eight hundred service See 800 service. EllA 1. Embedded Industrial Internet Appliance. A commercial development kit offered by Arcom Con- trol Systems for adding TCP/IP connectivity to products. 2. European Information Industry Association. EIMF European Interactive Media Federation. See European Multimedia Forum. Albert Einstein - Physicist Albert Einstein was a patent clerk in Switzerland for seven years before he was able to find the type of position he desired in an academic research environment. Einstein, Albert (1879-1955) A German scientist who is considered one of the greatest in the history of physics, best known for his special theory of relativity. Einstein moved first to Switzerland, where he was educated as a teacher of mathematics and physics, and then later to the United States. Unable to find a teaching or research position, he worked in the Bern patent office for seven years. Within two years of starting as ajunior clerk, Einstein had become a technical expert in the patent office. While there, he made EIA/TIA Cable Transmission Categories Cat. Transmission Speed Rating Typical installations Cat 1 No performance criteria specified. Cat 2 Rated to 1MHz Telephone wiring installations Cat 3 Rated to 16 MHz LAN, Ethernet, 10Base-T, UTPToken-Ring Cat 4 Rated to 20 MHz LAN, Token-Ring, 10Base-T, IEEE 802.5 Cat 5 Rated to 100 MHz WAN, Fast Ethernet, 100Base-T, 10Base-T 307 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary good use of his free time by writing a large volume of theoretical physics articles. By 1905, Einstein was writing about his ideas in electromagnetic energy and the photoelectric effect, building on and extending the work ofM. Planck. In the same year, he wrote his paper on the special theory of relativity, reinterpreting classical physics, and sup- ported Maxwell in hypothesizing that the speed of light was constant in all frames of reference. His con- cepts about the equivalence of mass and energy were tied in with the other writings at that time. This cre- ative intellectual output was astonishing, and the later recognition and corroboration of his ideas catapulted him into the history books and out of the patent office into a series of posts at universities in Eastern Europe, Western Europe, and America. In 1940, he became a citizen of the United States. In 1915, he published the definitive culmination of his writings on relativity, and in 1917 he proposed electromagnetic emission principles which led to the development of lasers. In 1924, he made further dis- coveries concerning the relationships between waves and matter. In 1921, Einstein was awarded the Nobel Prize in physics for his studies of the photoelectric effect. A crater on the moon has been named after him. EIPA 1. Electronic Information and Communication for Pedagogical Academies (Austria). 2. European Information Providers Association. 3. See European Institute of Public Administration. EIR 1. electronic incident report. Areport on anoma- lous or unauthorized activity on an electronic system. 2. Equipment Identity Register. A mobile services security database that aids in tracking lost or stolen communications devices. EIRP 1. Effective Isotropic Radiated Power. 2. Equivalent Isotropic Radiated Power. An ideal ra- diator providing a de facto common reference for radiated power. See isotroRic, isotropic antenna. EIRPAC Eire (Telecom Eireann) packet network. An X.75 packet-switched national data network in the Irish Republic. A number of charging bands provide various degrees ofEIRPAC connectivity to other nations. Band 1 provides domestic communications, Bands 2 and 3 service connections to a number of European countries, Band 4 supports destinations in NorthAmerica, and Band 5 services communications with other countries. Local access is provided in major cities (e.g., Dublin) and dialup through the public switched telephone network (PSTN) is available to remote subscribers with modems approved by the Department of Commerce. EIS 1. Epidemic Intelligence Service. A service of the U.S. Centers for Disease Control and Prevention. 2. See ESO Imaging Survey. 3. See Expanded Inter- connection Service. EISA See Extended Industry Standard Architecture. EISCAT See European Incoherent Scatter Scientific Association. EITA 1. enterprise information technology architecture. 2. See European Information Technology As- sociation. 308 EIU 1. economic intelligence unit. 2. Ethernet interface unit. 3. external interface unit. EKE 1. See electronic key exchange. 2. encrypted key exchange. See Encrypted Key Exchange Proto- col, public key. EKTS See Electronic Key Telephone Service. Electric Telegraph to the Pacific Act Ahistoric act of the U.S. Congress to solicit bids for construction ofa government communications line connecting San Francisco to major centers. The line was to be open to the use of all U.S. citizens upon payment of the appropriate charges. In July 1862, the Pacific Rail- way Act was enacted to " aid in the Construction ofaRailroad and Telegraph Line from the Missouri River to the Pacific Ocean " The Central Pacific Railroad Photography History Museum is a good source ofphotographs and information on railroad and communications history. http://cprr.org/Museum/ electrical wire Any conductive filament, usually metallic, that readily transmits current. Copper is very commonly used for telecommunications wires. One of the earliest documented long wires was a thread that conducted electric virtues over 600 feet in 1729. The thread was strung during electrical ex- periments conducted by S. Gray and G. Wheler. electricity A fundamental constituent of nature that is observable as positive and negative charges and currents through materials according to their conduc- tivity. The discovery and harnessing ofelectricity is the basis ofour current technological society. Elec- tricity arises from various sources, including friction (static electricity), light (photoelectricity), heat, chemical activity, piezoelectricity (pressure, especially in crystalline substances), and mechanical energy (as from a generator). Ancient observers were aware of various electrical phenomena, but it was not until the last 200 years that we have begun to understand their various properties and the fundamental principles that underlie them. electroabsorption EA. Aphenomenon in which the application of an electric field or voltage to a substance causes a change in optical absorption that oc- curs very quickly. The change is sufficiently strong to be detected, which lends itself to practical applications. The time it takes to control and apply the electrical field is the chieflimitation to the speed of the effect. When this phenomenon is associated with quantum wells, it is called the quantum-confined Stark effect. Electroabsorption is exploited in the field of spectros- copy and has been used to develop modulators for demultiplexing and detection. Electroabsorption light modulators have been integrated with laser diodes. See electroabsorption modulator, self-electro-optic effect device, quantum well, Stark effect. electroabsorption modulator EAM. Modulation of an optical beam by exploiting the electroabsorption properties of certain substances such that continuous- wave laser output (e.g., in dense wavelength division mutliplex optical networks) can be externally modulated to send digital information with rapid light pulses. In the late 1990s, the University of California, Santa © 2003 by CRC Press LLC Barbara, demonstrated the first traveling wave electroabsorption modulator at 18 GHz. In March 2001, Alcatel announded the launch ofa new EAM based upon the electroabsorptive properties of indium phosphide. The component was capable ofoperating at 40 Gbps with low power consumption. A number of commercial vendors are now supply- ing SONET/OC-192 EAM drivers for driving EA- modulated lasers at speeds up to 12.5 Gbps. For example, in March 2002, Oki Semiconductor released an EAM module monolithically integrated with a DFB laser suitable for 10 Gbps over distances up to about 40 Ian and Mitsubishi and Alcatel launched new 10-Gbps EAM lasers. electrode 1. An essential component of an electron tube. Any of the basic components, the electron-emitting cathode, controlling grid, or electron-attracting anode, are considered electrodes. Carbon arc electrodes are used for generating precise heat utensils for welding or fusing a variety of materials. They may be handheld or incorporated into precision cutting machines. The carbon burns away as the electrode is applied. Depending upon the application, compressed air may be used to blow away particles on the surfaces to be fused. Carbon arc welding requires safety shielding to protect eyes. Electrode-based devices require regular checking and cleaning and, depending upon the type and frequency of use, may require oxidized parts to be replaced. See fusion splicing. 2. A plate in a battery. electroluminescence The direct conversion of electrical energy into light. This process is used in display technologies, with electroluminescent materials such as zinc sulfide doped with manganese. See electroluminescent display. electroluminescent display EL display. A gridded display technology that incorporates an electroluminescent material sandwiched between outer panels. When exposed to high electrical fields, the inner material emits light. Like plasma panels, individual points are selectively lit through matrix addressing. EL displays are brighter than passive LCD displays but also require more power. See liquid crystal display, plasma display. electrolysis The production of chemical changes by passing an electrical current through an electrolytic material. See electrolyte. electrolyte A nonmetallic substance that, when chemically or electronically stimulated, becomes an ionized conductor. Electrolytic properties are widely . employed in electronics. Electrolytes are used electrical cells, rectifiers, etc. Various acids were commonly used as electrolytes in early inventions. electrolytic cell Apower-conducting (as opposed to power-generating) cell comprised ofa conducting liquid (the electrolyte) and two identical electrodes. Electrolytic cells are used in refining, reduction, and electroplating processes. electrolytic detector, liquid detector A radio wave detecting device patented by R. Fessenden in 1903. It was discovered accidentally when Fessenden was seeking ways to improve on his hot-wire barretter. A broken filament led to the discovery that signals could be received better through the separate pieces of filament in an electrolytic solution than with a single piece of filament. From this, Fessenden combined nitric acid and a platinum wire into a rectifier that could detect both continuous and damped waves. The electrolytic detector was an important milestone in radio history, as it provided a means to create a much more sensitive receiving instrument. Most electrolytic detectors required an outside power source, though some were manufactured with a built-in battery integral to the design. See barretter, Shoemaker detector. electrolytic paper tapeA type ofpaper tape used on some of the old telegraph systems in which a stylus passed an electrical signal onto the coated tape to pro- duce an image of the message being transmitted. The image on early systems was often blue, though the amount ofcurrent on an electrolytic system can influence the color of the image. electromagnetA device that has a significant magnetic field only when current is flowing through it. The strength of the wire is dependent on the size and type ofmaterials used, the amount of current, and the number of coils. Electromagnets are used extensively in appliances, industrial hoists, telephones, public address speakers, and bulk erasers. You can make a simple electromagnet by wrapping a conductive wire around an iron nail and passing current through it (taking care not to touch any of the live wires). This in tum can be used to magnetize the end ofa screwdriver by stroking the nail in one direction over the screwdriver. Quite handy for holding screws in place, but be wary of using magnetized screwdrivers near electronic components. See bulk eraser; Faraday, Michael; solenoid. electromagnetic Embodying electric and magnetic properties. See electromagnet. electromagnetic communications Communications that employ the propagation of transmission waves through space. Meaningful signals are sent in many ways, with light, radio waves, microwaves, etc., usually by modulating the transmission of the radiant energy in some way. electromagnetic deflection The directing of the path of an electron beam by means ofa magnetic field ( often in the form ofa coil). electromagnetic field 1. A field of magnetic influence around aconductor produced by a current flowing through the conductor. See electromagnet. 2. To- gether, an electric field and its associated magnetic field. The magnetic field is perpendicular to the lines and direction of force. See right-hand rule. electromagnetic interference EMI. Undesirable noise, degradation, overlap, or echo in an electromagnetic transmission. electromagnetic pulse EMP. A large or fast-mov- ing electromagnetic transmission that is quicker, or burstier than the immediately preceding and succeed- ing transmission. Sometimes apulse is a natural phenomenon, such as lightning, or it can be a deliberate means of creating a signal or carrying information. 309 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary electromagnetic spectrum The range, or diagram- matic relationships, of the known types of electromagnetic radiation, organized by wavelength. electromagnetic wave The radiant energy produced by an oscillating electric charge. Infrared, ultravio- let, gamma, visible wavelengths, and cosmic rays are some examples. electromotive force emf. Descriptive of the pressure of the movement of electrons through a circuit, sometimes described as similar to the movement of liquid through a closed piping system. Indeed, for many decades the two kinds of movement (electrical and liquid) were assumed to be the same, and early scientists spoke of emf as an electrical fluid. The discovery of the relationship between magnetic and induced electrical forces helped scientists to understand emf. An external influence (battery, power supply, etc.) can cause an electron charge to flow through a conductive medium creating an electromotive force. See Faraday's laws, volt. electronA minute, elementary particle of matter, carrying a negative electrical charge. Electrons are nor- mally found surrounding a positively charged nucleus. The term is derived from the Greek word elektron (amber) but was first used with this specific meaning by GJ. Storey in 1891. See positron. electron beam A stream ofelectrons traveling close together in the same trajectory, directed by a magnetic field. An important constituent ofcathode-ray tube (CRT) technology widely used in TV and computer monitors. electron microscope An optical-electronic instrument that provides magnification of minute struc- tures by means ofrecording the movement of a fo- cused beam ofelectrons. The results were originally displayed on fluorescent screens or photographic plates; computer monitors are also used. Early electron microscopes could enlarge images 100 times more than the finest optical microscopes of the time, but the images were limited to black and white still objects. New techniques were continually sought to increase the range of objects that could be imaged and the ways in which they could be represented. Com- puter enhancement and interpretation has opened a wide range ofpossibilities. electron tube A device in which the movement of electrons is conducted within a sealed glass or metal container. While electron tubes were made of glass for many decades, some all-metal tubes came into use in the mid-1930s. The most common implementation of the electron tube is the vacuum tube, since the life of the electron-emitting materials could be extended by removing the air or encasing a controlled mixture of gases. The most important evolutionary development in the history of the electron tube is the Audion, the commercial name for a triode, a three-element tube with a control grid invented by Lee de Forest. One of the most important adaptations of the vacuum tube is the cathode-ray tube still widely used in television sets and computer monitors. See anode, Audion, cathode, cathode-ray tube, vacuum tube. 310 AVariety of Electron Tubes The most common types of electron tubes used in electronics for many decades were three-element (or more) vacuum tubes. Experimentation led to the development of many different types of tubes for different purposes, and numbering systems were set up to keep track of parts so consumers could replace broken or burnt out tubes. For the most part, semiconductor components have replaced electron tubes, ex- ceptfor some highfrequency applications. This interesting assortment is from an exhibit at the American Radio Museum. electronic bulletin board See bulletin board system. Electronic Certification An electronic signature that serves the same purpose as a written signature on a physical document (usually a letter, contract, or ad- ministrative approval). Electronic Certification is ac- complished through cryptography, typically key cryptography. See DSS. Electronic Classroom A commercial Macintosh- based distance-learning audiographics multimedia videoconferencing tool written by Robert Crago, an Australian developer. Electronic Classroom provides images, QuickTime compressed video, and voice over public switched telephone networks (PSTN). electronic commerce, ecommerce Financial and barter transactions conducted across data networks using electronic means of communications and agree- ments, including the exchange of documents, signa- tures, virtual money, etc. In the earliest ecommerce implementations, people used bank machines to carry out simple deposit, withdrawal, and balance inquiry transactions. On the Internet, they simply communicated the terms of commercial transactions through email but, since then, some significant changes have occurred. There © 2003 by CRC Press LLC are now banking machines that can transact traveler's check purchases and loan negotiations and provide more complex information services. Similarly, with the dramatic growth of the World Wide Web, tens of thousands of companies and individuals have ex- pressed the desire to conduct remote financial transactions, and sophisticated secured electronic commerce systems are being developed and promoted. Shopping cart systems have become common on the Web, and online banking services are prevalent, along with new services such as PayPal and Billpoint that allow a user to manage funds within a virtual bank through email and Web browsers. By the mid-1990s, there were initiatives to standardize transaction mechanisms, efforts to promote private and secure ecommerce, and many individual ways to exchange money on the Internet. See certificate, digital signature, Electronic Data Interchange, electronic mall, encryption, JEPI, Pretty Good Privacy. Electronic Commerce Service ECS. ECS is a set of electronic mail and verification services developed by the U.S. Postal Service (USPS) to offer secure electronic mail so that it becomes an electronic extension of the USPS physical mail system. USPS is cooperating with private firms to develop this technology. Various aspects of the USPS plans include personal and professional certificate services through aCerti- fication Authority (CA), time and date stamping (in essence an electronic postmark), certified email.re- turn receipt, verification, and archiving. It is important to consider that USPS email differs from personally forwarded email in some of its legal safeguards, and that USPS has a history of statutes and precedences which may make it attractive to business users. As with all major milestones in U.S. postal history, the USPS released a commemorative stamp, in early 1996, to launch their electronic venture. The computer whose birthdate was commemorated was the ENIAC, which certainly deserves credit for its his- torical importance, but the system that should probably have been honored as the first large-scale computer is the Atanasoff-Berry Computer, which pre- ceded the ENIAC. Electronic Communications Privacy Act of 1986 ECPA. An Act of the U.S. Congress, adopted to address issues of privacy related to the growing preva- lence and use of computers and related digital technologies, especially for communication. The ECPA was passed to address more specifically issues ofpri- vacy pertaining to electronic surveillance. Prior to the ECPA, privacy and electronic surveillance issues were generally covered in Title III of the Om- nibus Crime Control and Safe Streets Act of 1968. This Act was established a decade before personal computers began to be widely distributed and three decades before the use of the Web and inexpensive surveillance devices were widely available to consumers. Thus, it was felt that issues not clarified by Title III as to new and emerging technologies needed to be re-evaluated. The issues were and are complex. The Federal Bureau ofInvestigation (FBI) and local law enforcement agencies were concerned about criminals using new technologies as a means to facilitate criminal communications and acts. Private citizens, on the other hand, were concerned that too much power in the hands of authorities could lead to invasion of the privacy oflaw-abiding citizens. Thus, the Act needed to be able to satisfy the needs of law enforcement officers without impinging on those who were not involved with criminal activities. ~!:~!i:!f;~;X~lf:~~~~~~;Jtfy~E::. tronic mail, and it extended the concept and definition of intercept to apply to electronic textual data (prior to this, most privacy laws pertained to spoken voice communications over phone lines, e.g., wire- tapping). Controversy followed the lawmaking, with detractors saying that the final version differed from the proposed version and that it did not go far enough to protect civil liberties. See American Civil Liber- ties Union, Cyberspace Electronic Security Act of 1999, Electronic Freedom Foundation, Encrypted Communications Privacy Act. Electronic Data Interchange ED!. A series ofstan- dards developed primarily for business communications, EDI is a scheme for network interchange of electronic messages and documents, often between different companies or government agencies. EDI software works in conjunction with applications software. Files are extracted from an application, converted into a standard ED I format, and passed on to the communications software for transmission. EDI is not secure in and ofitself and may be combined with authentication and encryption schemes. Practi- cal applications include the interchange ofinvoices, purchase orders, policy documents, RFQs, waybills, cost estimates, etc. The primary international standard for formatting ED I messages is Electronic Data Interchange for Administration, Commerce, and Transport (EDIF ACT). ED IF ACT messages are included within an EDI envelope. The interchange IDs ofsender and receiver must be agreed upon. Their addresses are described in the X.400 standard (ITU-T X.400/ X.435). See X Series Recommendations. electronic dataprocessing EDP. A system for receiving, manipulating, translating, and storing data, sometimes in large amounts. For example, numbers may go in, and paychecks, employee statistical information, or sales demographics may come out. Electronic Directory ED. An informational database based on a directory standard, such as X.SOO or LDAP, intended to help integrate various directories on a network. Thus, access is improved over that of searching and querying various directories, and different formats and protocols are made transparent to the user. EDs are ofinterest especially to corporations, educational institutions and libraries. See X.500. electronic filing system EFS. A generic phrase for various means of submitting forms and other admin- istrative information or applications via computer 311 © 2003 by CRC Press LLC . Fiber Optics Illustrated Dictionary around the equator at 2000 kilometers using CDMA in the i-iS-band frequencies for down/uplink transmissions, and C- or Ku-band for feeders. The target service area is the equatorial belt between 23 ° north and south latitudes, comprising over 75 countries and a high proportion of the world's population. In spite of the large number of people who live in this region overall, many of them are in remote, small, rural communities with few or no wired communications services. From the user's point of view, ECO-8 telephony services are functionally similar to cellular. The caller's desired number is transmitted through the satellite system to the local gateway where it is further relayed to a public phone circuit, wireless system, or to another ECCO satellite to link with another subscriber. ECCO. StandardsA collection of standards describing configurations, signals, and other communications parameters for various electronic connecting interfaces. These are often used in conjunction with ITU- T specifications for protocols and functions. Probably most familiar of the Interface Standards are EIA- 23 2- D and EIAffIA- 23 2- E, which are 1987 and 1991 updates to the decades-old RS- 232 specification for serial transmissions between data terminal equipment (DTE) and data communications equipment (DCE). This standard has been widely imple- mented in desktop computers and other devices and is commonly used for communicating with modems, remote terminals, and printers. Most systems support EIA- 23 2- D and EIA!fIA-23 2- E through 25-pin D connectors, though minimally nine pins are needed to implement the specification, and 9-pin D connectors (EIA-574) are sometimes used. The EIA has also defined faster standards for serial communications, including EIA-422 (balanced signals), EIA-423 (unbalanced), EIA-485 (multi- point), and EIA-530 (EIA-422 with 25-pin D con- nector). EIA standards additionally encompass wiring connectors and topology, including building wiring and network backbones. EIAITIA. connectors (EIA-574) are sometimes used. The EIA has also defined faster standards for serial communications, including EIA-422 (balanced signals), EIA-423 (unbalanced), EIA-485 (multi- point), and EIA-530 (EIA-422 with 25-pin D con- nector). EIA standards additionally encompass wiring connectors and topology, including building wiring and network backbones. EIAITIA