Fiber Optics Illustrated Dictionary - Part 57 ppt

Fiber Optics Illustrated Dictionary Kalman filter. The discrete Kalman filter (DKF) at- tempts to estimate the state ofa discrete-time-controlled process. The extended Kalman filter (EKF) handles nonlinear situations by linearizing (e.g., with partial derivatives) about the current mean and co- variance. The Kalman filter is now an important aspect of so- nar and radar tracking, guidance, and navigation systems. It has also been used in satellite orbit calcula- tions for various space missions. Recently, fiber optic gyroscopes (FOGs) in combination with Kalman filters, have been used in mobile robot systems. The Kalman filter fuses the FOG sensor data with the robot odometer to provide more accurate dead reckon- ing than is possible through traditional odometric systems in accessible price ranges. Kangaroo Network A commercial hardware/software product from SpartacuslFibronics designed to enable ffiM mainframes to intercommunicate with other networks using TCPIIP. Kangaroo Working Group A working group on telecommunications and the information society that works with the European Internet Foundation look- ing into issues associated with creating a level play- ing field in terms ofInternet use and access in Eu- rope, ensuring a balance between private industry and government. The Kangaroo Group has been actively involved in conferences since the mid-1980s and has actively debated Internet regulations and barriers to the use of cyberspace. Kao, Charles K. (1933- ) A Chinese engineer and significant pioneer in fiber optic communications, Kao studied in Britain and became head of the optical communication program at ITT's Standard Tele- communications Laboratories, Harlow, U.K., in De- cember 1964. Along with G. Hockham, Kao cham- pioned the idea of single-mode optical fiber transmission systems and coauthored "Dielectric-Fiber Sur- face Waveguides for Optical Frequencies" in Proc. IEEE (1966). He followed this up with work on the structure of fiber communications and subsystems. Kao and Hockham were correct in proposing that loss in fiber signals was due to impurities in the transmission medium rather than inherent limitations in the glass itself. During the period 1987-1996, Kao taught and became president of the Chinese University of Hong Kong. He became a Trustee for the S.K. Vee Medi- cal Foundation in 1990 and is chairman ofTranstech Services Ltd. He has received many honors from engineering societies. See Hyde, J. Franklin; Kapani, Narinder; Keck, Donald. Kapani, Narinder Singh (ca. 1930- )Aprolific In- dian inventor, Kapani has been awarded more than 150 patents for various instruments and laser technologies. In 1954, in Nature, Kapani and Hopkins described a means to clad optical fibers to keep the light within the waveguide This was an important milestone in optical technologies, greatly extending the distance over which signals could travel through a fiber waveguide. The following year, Kapani developed a way to fabricate high-quality fiber 552 filaments and coined the term fibre optics. By 2000, Kapani had founded a series of companies, including K2 Optronics for concentrating on fiber optic communication devices. See Hansell, Clarence; Kao, Charles. Kapor, Mitchell "Mitch" (1950- ) The instigator of several historic high profile computer-related orga- nizations, Mitch Kapor founded Lotus Development Corporation in 1982, and was the designer of the well- known Lotus 1-2-3 spreadsheet software. In 1990, he cofounded the Electronic Frontier Foundation (EFF), a nonprofit civil liberties organization. Kapor has chaired the Massachusetts Commission on Computer Technology and Law and served on the board of the Computer Science and Technology arm of the Na- tional Research Council, and the National Informa- tion Infrastructure Advisory Council. Karbowiak, Antoni E. A researcher at Standard Tele- communications Laboratories in a group established by Alec Reeves in 1962. Karbowiak and his collabo- rators conducted pioneer work with optical fibers as potential transmission technologies at a time when most scientists considered the lossiness of (uncladded) fiber to be too great to be of any practical value. He became a collaborator with a young, talented Chinese engineer, Charles K. Kao, who is now considered a significant pioneer in fiber optics. In 1964, Karbowiak left STL to chair the electrical engineering department at the University of New South Wales. See Kao, Charles K.; Snitzer, Elias. Karnaugh map A two-dimensional truth lookup table organized to facilitate combination and reduc- tion ofBoolean expressions. This is useful in digital logic circuit design. See Boolean expression. Karn's algorithm A mathematical formula for im- proving network round-trip time estimations. It grew out of packet radio network algorithms but now is more widely applied. In layered network architec- tures, the algorithm helps the transport layer proto- cols distinguish among round-trip time samples. It is used in Transmission Control Protocol (TCP) imple- mentations to separate various types ofreturn transmissions and to establish whether or not to ignore re- transmitted signals. It is also applied to backofftim- ers in Point-to-Point (PPP) tunneling networks. See ATM, Jacobson's algorithm, Point-to-Point Tunnel- ing Protocol. Kawakami, ShojiroAJapanese researcher who has contributed articles about many aspects offiber optic technology, but who is chiefly known for his development ofgraded-index fiber and ofa "photonic crystal" that acts like a prism in that it can separate optical signals with different wavelengths. The technology was developed by Shojiro (Tohoku Univer- sity) and further developed in conjunction with Opto- electronics Laboratories, and NEC, in 1997. This in- vention has potential as part of add/drop multiplexer components in dense-wavelength transmission systems, as envisioned by NEC. • Kawakami was recognized as a Fellow of the IEEE Society for his contributions to fiber optics, in 1997. See Hicks, John; photonic crystal; Yablonovitch, Eli. © 2003 by CRC Press LLC Kay, Alan (1940- ) A precocious child and avid reader, Kay was inspired by the work of Seymour Papert at MIT in the 1960s. Kay was committed to the idea that computers should be easy, fun, and accessible, and began developing what was to become the Smal1talk object-oriented programming language. He became a group leader at Xerox P ARC in the early 1970s, a period when tremendous innovation in mi- . crocomputer technology and user interfaces was stimulated at the lab. Kazarinov, Rudolf F. A Russian physicist and engineer, Kazarinov originally carried out research at the IOFFE Physico-Technical Institute in St. Peters- burg. He then came to the u.s. to conduct research at the Bell Laboratories Photonics Circuits Research Department. Kazarinov made significant pioneer theoretical contributions to semiconductor laser technologies beginning in the early 1960s. His contributions include the double-heterostructure laser, distributed-feedback (DFB) laser, and intersubband lasers. He also .coauthored a number of patents, including hybrid lasers for optical communications, with Greg Blonder, Charles Henry, et al. In 1998, Kazarinov was coawarded the prestigious Rank Prize in optoelectronics for his involvement in the 1994 development of the quantum-cascade (QC) laser, along with Federico Capasso. See Capasso, Federico; laser history. Kbps kilobits per second; 1000 bits per second. It is sometimes written Kbits/s. KBps kilobytes per second, 1000 bytes per second. It is sometimes written Kbytes/s. KDC See key distribution center. KDD 1. Knowledge Discovery in Databases. A branch of artificial intelligence applied to database query, search, and retrieval. 2. Kokusai Denshin Denwa Company, Ltd. AJapanese supplier of international telecom services, equipment, and facilities. KDDI Corp. Japan's second-largest communications carrier, descended from Kokusai Denshin Denwa Kabushiki Kaisha (KDD), which was founded in 1953. In April 2001, KDDI announced Java support for its mobile phone services through its CLDC- and MIDP-conforming application interface called KDDI-P. KDD R&D Laboratories, Inc. is the research and development division. It was founded when KDD was detached from the Nippon Telegraph and Telephone Public Corporation and moved into a new research facility for conducting research in international communications in 1960. It became independent ofKDD in 1998 and was remerged, along with other firms, in 2000 to become KDDI's R&D division. The R&D lab has developed TDMA technology for satellite communications, submarine fiber optic cables, G3 facsimile coding technologies, magneto-optical discs, and data compression and transmission technologies. KDD Fiber Labs, Inc., a KDDI Group Corporation, develops fiber optics technologies, including WDM optical amplification and various types of light sources. KDKA KDKA originated as amateur callsign 8XK, operating from the garage of Frank Conrad. It is a historically significant Westinghouse Electric radio broadcasting station in Pittsburgh, Pennsylvania that used radio waves to report returns of the Harding-Cox Presidential race to the American public, on Novem- ber 2, 1920. This was about 14 years after the earliest experimental broadcasts and a week after receiving its own official broadcasting license. By the following year, KDKA was making regular public broadcasts and radio broadcasting was booming, with more than 500 broadcasting stations sprouting up around the country. KDKA was still broadcasting under the same callsign more than 80 years later. See CFCF; Herrold, Doc; radio history. KEA See Key Exchange Algorithm. Kearney System KS. A parts numbering scheme developed for Western Electric telecommunications equipment, named after the town in New Jersey where the plant was located. The KS system has generally been superseded with vendor-specific and industry standard codes, although Kearney numbers are still found on some pieces of equipment. I Keck, Donald B. (1940- ) Keck studied at Michi- gan State University, graduating in 1967 and went to work as a senior research scientist at Coming Glass Works in 1968, becoming involved in fiber-related projects with Robert Hall. He subsequently served as director of the Applied Physics division and VP of Optics and Photonics and then became VP and director of the Optical Physics Technology group. Along with Maurer and Schultz, Keck was awarded the National Medal of Technology in 2000 for making low-loss optical transmission fiber apractical re- ality. keepalive interval The period of time between keepalive messages. The amount of time depends upon the type of network and the type of activity taking place. For example, for a computer process, the interval might be measured in nanoseconds, whereas for a user activity, it might be measured in minutes. See keep alive message, keep alive signal. keep alive message Messaging between network devices that indicates that a virtual circuit between the two is still active (alive). See keepalive interval, keep alive signal. keepalive signal A network signal transmitted during times of idleness to keep the circuit from initiat- ing atime-out sequence and terminating the connection due to lack of activity. See keepalive interval, keepalive message. Kelvin balance, ampere balanceA historical instrument for measuring the absolute value of an electrical current, named after its inventor, William Thompson (Lord Kelvin). It is essentially a galvanometer that measures the force produced by the magnetic field associated with the passage ofcurrent through a con- ductive medium. In one of its historical fabrications, the instrument resembled a small reel-to-reel tape recorder, with two low, flat spools coiled with wires connected to one another in series positioned a few inches apart. A piv- oting beam balance enabled a set of rings to move 553 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary freely between the coils. Afinely incremented ruler- like gauge stretched the length of the instrument, in front of the coils, from the outer edge of one to the other. The whole thing was generally encased within aprotective brass and glass enclosure. The instrument was sold with a set ofweights. The current to be measured passed through the wire coils to create an at- tractive force referenced against a known weight. Two ampere balances were designated as legal standard instruments in 1894. Kelvin effect When an electric current passes through a single homogeneous but unequally heated conductor, heat is absorbed or released. This effect is named after William Thompson (Lord Kelvin). Kelvin scale Atemperature scale proposed by Will- iam Thompson (Lord Kelvin), based on the efficiency ofareversible machine. Zero is designated as the tem- perature of the sink of the machine working effi- ciently, that is, complete conversion ofheat into work, asituation possible only at absolute zero on a gas tem- perature scale. Zero degrees Kelvin (0 K) can also be expressed as -273.15 degrees Celsius (-273. I 5°C) or -459.67 degrees Fahrenheit (-459.67°F). Kelvin, Lord William Thomson (1824-1907). A Scottish physicist and mathematician who made significant contributions to the field of thermodynam- ics, and applied his theories to the dynamics and age of the earth and the universe. He utilized the field concept to explain electromagnetism and its propa- gation. The concept of an all-pervasive "ether" was still prevalent at the time, so he explained a number of his observations within this context. He also developed the siphon recorder, a number of types of voltmeters, and an ampere balance, and was involved in laying the transatlantic telegraph cable. The Kelvin scale and Kelvin effect are named after him. Kenbak-l Adiscrete logic microcomputer designed by John V. Blankenbaker, introduced in 1971 as the Kenbak-I Digital Computer. It featured 256 bytes of memory, three programming registers, and five ad- dressing modes. The controlling switches were on the front panel of the machine. It was advertised in the September 1971 issue ofScientificAmerican, 3 years prior to the introduction ofthe Altair, for only $750. One of the earliest microcomputers, the Kenbak-I was apparently ahead of its time. Unfortunately, only 40 machines sold over the next 2years, and the Cali- fornia-based Kenbak Corporation missed a significant business window by a narrow margin. One year after the company closed, the Altair computer kit caught the attention ofhobbyist readers ofPopular Electronics magazine and sold over 10,000 units. See Altair, Arkay CT-650, Heathkit EC-I, Intel MCS- 4, Micral, Simon, Sphere System. Kendall effect Distortion in a facsimile record, caused by faulty modulation of the sideband to carrier ratio of the signal. Kennelly, Arthur Edwin (1861-1939) A British- born American mathematician and engineer who studied mathematical aspects ofelectrical circuitry. He also studied the properties of the Earth's atmo- sphere and its effects on radio waves and suggested that 554 an ionized layer above the Earth could reflect radio waves, an idea soon after independently published by Oliver Heaviside. Kennelly-Heaviside layer In 1902, A. Kennelly and O. Heaviside proposed, independently of each other, that an ionized layer surrounding the Earth could serve as a reflecting medium that would hold radia- tion within it. This led to the discovery ofa number of regions surrounding Earth and utilization of the characteristics of some of these layers in long-distance wave transmission. It also led, in the 1920s, to confirming experiments in which radio signals were bounced offthis reflecting layer. See Heaviside, Ol- iver; ionosphere; Kennelly, Arthur. Kepler, Johannes (1571-1630) Aphysicist and as- tronomer from Swabia (now Austria) who studied the planets and endeavored to mathematically describe planetary motion. In 1604, he published Astronomiae pars Optica describing light travel, shadows, the functioning of the eye, and other concepts fundamen- tal to modem optics. He also made important studies in optics related to better studying the planets. In 1611, he published Dioptrice which described the properties oflenses, including inversion and magni- fication, and a new form of telescope now known as the astronomical telescope. Ke~ler may have been the first to use the term "satellite' to describe orbiting moons. Kerberos authentication An authentication system developed through the MIT Project Athena effort. Kerberos is aclient/server security mechanism based upon symmetric key cryptography. Each user of the Kerberos system is assigned a non secret unique ill and selects a secret password. The secret password is provided to the Kerberos system and is not intended to be divulged by either party. The user then uses the password to request access from the system. The iden- tity of the user is verified by generating a random number and presenting a problem that can likely be solved only by the authentic user, thus providing access to a message on the system. The symmetric nature of the system is in the use ofthe same encryption and decryption key. For security purposes, long, randomly selected strings work best with this system of cryptography; otherwise it may be vulnerable to password-guessing attacks. Kermit Project Anonprofit, self-supporting project at Columbia University for the support of the Ker- mit Protocol and the development ofKerrnit-related technologies. The project also includes information on documentation, licensing, and technical support for users of the Columbia implementation ofKermit. See Kermit Protocol. http://www.columbia.edu/kerrnit/ Kermit Protocol Apacket-oriented, platform-independent file transfer protocol developed at Colum- bia University in 1981. Hundreds of Kermit imple- mentations support the 7-bit and 8-bit transfer of text and binary files. They are commonly used over asyn- chronous, serially connected local area networks (LANs) and phone lines. Kermit is flexible and con- figurable. © 2003 by CRC Press LLC Kermit is not the speediest protocol, as each packet is checked and acknowledged as it is transferred, but it is reliable, widespread, and well supported, especially in academic institutions; when all other proto- cols fail, it's often the one which will get the file transfer done. There are numerous terminal emulators based on Kermit, with VT52 and VT100 versions being common. Telnet, an important protocol for remotely connecting to a network host, has also been implemented with Kermit. Kermit is a workhorse, but its use in its original form has declined. Most local area networks and the In- ternet now use other network connection and file transfer mechanisms such as ATM, Ethernet, and FTP, but traditional Kermit is still useful for phone links and small networks interconnected with basic serial connections. Updated versions of Kermit may greatly extend its useful life. Internet Kermit Service is a file transfer service described by da Cruz and Altman at Colum- bia University based on a combination of the widely used Telnet Protocol and Kermit Protocol. It supports both anonymous and authenticated access. Kermit over Telnet enables the traversal of firewalls and a number of security options. By providing some ad- vantages over File Transfer Protocol (FTP), this Ker- mit configuration is apractical option for distributed networks, including the Internet. The registered lANA port for Kermit connections is 1649. Kermit is an open freely distributable protocol, so it can be used for software applications development, but Columbia's implementation of the Kermit protocol is copyrighted. See FTP, Kermit Project, XMo- dem, YModem, ZModem. See RFC 2839, RFC 2840. kernel I. Line within a conductor along which the current-resulting magnetic intensity is zero. 2. Low level of an operating system at which processes and resources (such as memory and drivers) are created, allocated, and managed. Functions and operations at the kernel level form a bridge between hardware and software resources and are mostly or completely transparent to the user. Kerr cellA device used to modulate light in conjunction with polarizers. The cell contains electrodes to direct the necessary electric field for inducing the Kerr electro-optical effect and the material being in- fluenced by the combination of the field and a beam of polarized light. Photodetectors may be used in conjunction with the Kerr cell to determine if or when the effect occurs. Kerr cells have been used in the fabrication of high-speed optical shutters. Kerr effect There are actually two Kerr effects named after John Kerr, so it is best to specify the one of rel- evance. For simplicity of reference, they are sometimes abbreviated as electro-optical Kerr effect (EKE) and magneto-optical Kerr effect (MOKE), especially in the field of microscopy. See scanning near-field magneto-optical microscope. Kerr electro-optical effect A phenomenon discov- ered by John Kerr in 1875. It is an electro-optical effect in which certain substances become double refracting (birefringent) in the presence of strong electric fields or in which certain specific substances become double refracting in smaller electric fields. In other words, a single incident ray of light is refracted as two, with the two rays oscillating in mutually perpendicular planes. Isotropic liquids or gas, for example, show the Kerr effect and become optically anisotropic when subjected to a consistent electric field perpendicular to a beam of light. To account for the effect, it is theorized that the application of the electro-optical energy causes a reori- entation ofamaterial's molecular structure. Since the effect is not universal across materials and levels of electromagnetic influence, it is often studied with certain parameters held within controlled limits, such as the constancy of the electric field and the wavelengths of light. Since the Kerr effect can be induced through controlled conditions and occurs quickly, various re- searchers have suggested that it may have practical applications in troubleshooting optical transmissions or in increasing bandwidth in optical communications systems. See Kerr cell, Pockels effect. Kerr magneto-optical effect The change in a light beam from plane polarized to elliptically polarized when it is reflected from the reflective surface of an electromagnet. The degree of rotation is directly pro- portional to the degree of magnetization of the reflective material. The transmissive aspects of this effect were first observed and described by Michael Fara- day in the 1840s and researched further by John Kerr three decades later as to its reflective properties. Be- cause oftheir relationship, the Faraday and Kerr effects are often described together. This magneto-optical effect is useful for studying magnetic effects in superlattices and giant magneto- resistive (GMR) effects. GMR technology was dis- covered in the late 1980s and has since developed into a new, highly sensitive sensor design for disk drives. The effect can also be put into practical use for measuring current in power lines using a polarized laser to measure the degree of rotation. See Faraday effect, giant magneto-resistance. Kerr, John (1824-1907) A Scottish-born physicist best known for discovering and describing the Kerr electro-optical effect. Kerr carried out research under the direction of William Thompson (Lord Kelvin). See Kerr electro-optical effect. keV Abbreviation for kiloelectronvolt. Kevlar The DuPont tradename for a strong, synthetic multipurpose material that is, ounce-per-ounce, about five times as strong as steel. In the 1960s, a new liq- uid crystal polymer fiber was invented by Stephanie Kwolek; Kevlar is the commercial embodiment of this fiber. Kwolek also invented N omex, a fiber used in electrical insulation. Kevlar is used in applications where strong, light, flexible materials are needed, such as bulletproof vests and protective sheathings for sensitive or electrically active materials. Kevlar tape and Kevlar strength members are used in fiber optic cables. A water-resistant sheath is often fitted over the Kevlar or Kevlar-impregnated inner layers for further 555 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary protection from the elements (typically PVC or poly- ethylene). Kevlar is sometimes mixed with building materials to increase strength and resilience in the event of industrial vibrations or earthquakes. Carbon steel or ceramic cutters are generally used to cut the Kevlar components that serve as strength members in fiber optic cables. key n. 1. A small, physical security device, often made of metal, inserted into a matching lock receptacle to lock/unlock or activate/inactivate an obj ect or structure. It's usually the shape that allows a lock to be opened or closed, but more recent data-compatible keys may have magnetic stripes rather than physical indentations. 2. In an image, the overall tone or value of the image, often used to adjust camera settings to balance the amount of light or to screen out certain colors or light intensities (e.g., chroma key). 3. A switch for opening or closing a circuit. 4. In a database, an organizational means to locate desired information without searching the entire content of the database. 5. On keyboards, keypads, phone pads, etc., a small, roughly cubic, raised, movable, input attach- ment intended to be depressed, usually by a finger, to make a selection. 6. The modem equivalent of the switch on an old phone. key, telegraph A signaling device allowing the input of code, usually Morse code, and transmits it to the communications channel. The key superseded the Key Encryption - Basic Concepts Concept Description key agreement An encryption key establishment mechanism that is common to asymmetric cryptographic exchanges but may also be used in symmetric exchanges. In key agreement, a pair of entities, wishing to engage in a secured communication without prior arrangement, make use of public data (e.g., a public key) to negotiate a common key value unique to their communication (i.e., not known or used by other entities). When a Diffie- Hellman technique is used, key agreement is arranged without the need to transfer the key. See Diffie-Hellman. key center A trusted, centralized distribution point (e.g., separate server machine) capable of administering the use of key-encrypting "master" keys to encrypt and distribute session keys for secured communications. key confirmation The process of ensuring that participants in a key-secured communication are legitimate by detennining whether they do indeed possess a shared symmetric key. key distribution center In symmetric digital cryptography, a key center that provides encryption! decryption keys to two or more entities that wish to engage in a secured communication through an agreed-upon ,key distribution protocol. These keys are often session-related. key escrow A security system component in which part or all of a cryptographic key is entrusted to a third party to hold "in escrow." The key "bank" or authority is responsible for storing and releasing the keys to a party involved in a communication, provided that party submits proper authorization. The authorized recipient can then use the key to decrypt a message. There has been considerable debate over the use of escrow authorities. On the one hand, some individuals feel no one should have any part of a communication other than the sending and receiving parties. On the other hand, some believe it is necessary to have a third party that can be served a warrant to hand over information critical to the maintenance of national security and the carrying out of law enforcement activities. It is also critical, for the system to work, for the authority to be highly reliable, accountable, and secure. See key generation, key recovery. key establishment The processes of key generation, storage, and distribution that together enable a secured key-related communication association to be established. key exchange The transmission or recording of a software key with another party, or swapping among two or more parties. See encryption, PGP, key generation. key generation The process of creating a software key for security uses. Once this has been done, it is expedient to keep track of information related to keys (location, password, etc.) so that key generation does not have to be done again. Portable devices for generating a key are sometimes used in conjunction with keyless security locks on building premises. 556 © 2003 by CRC Press LLC portfule of earlier systems. See telegraph history. key encryption A personal or public identifier intended to establish the owner or recipient of a secure encoded message. Key-related negotiations may be symmetric or asymmetric and may be based upon public keys, private keys, or a combination of both. Key encryption may be based upon a long-term escrow system or upon short-term session-based communications. Apublic key cryptographic scheme consists of apublic key provided openly to anyone who wishes to send an encrypted message, and aprivate key used by the recipient to de-encrypt the received message. The Key Encryption chart provides a summary of some of the basic concepts. See certification, Clipper Chip, cryptography, encryption, Pretty Good Pri vacy. Key Exchange/Encryption Algorithm KEA. An asymmetric key encryption algorithm similar to the Diffie-Hellman algorithm, that utilizes 1024-bit keys. KEA was originally developed by the National Se- curity Agency (NSA) as a classified security mechanism whose status was changed in June 1998. See Clipper Chip, Diffie-Hellman, key encryption, SKIP- JACK. Key ContactAservice of British Telecom that com- prises an 11 th phone number (nonmobile) in addition to the key numbers kept by a business subscriber in BT's Friends & Family Key Numbers service. See key numbers. key illumination The lighting of a key on a keypad or keyboard to signal its status or facilitate its location. The keys may be illuminated to indicate that they Key Encryption - Basic Concepts, cont. Concept Description key length The number of symbols, usually expressed in bits or bytes, used in representing an encryption key. In general, the longer the key length, the greater the possible number of ways in which the data may be scrambled to ensure that it cannot be easily decrypted by an unauthorized party. key Iifetimellifespan The time span or expiry date associated with an established cryptographic key. The expiry period or lifespan may be determined in advance by an issuing authority, especially in session-related key assignments, or may be dynamically determined. The key lifetime is also determined in part by users. Ifa user loses or forgets or misplaces a key, its effective lifetime has ended even if the capability to use it still exists. Some key cryptography systems will explicitly include a parameter that determines the lifespan of a key (e.g., until the session is terminated). The capability to terminate a key is important in situations where key assignments must be reused in a dynamic resource-conscious system (e.g., session-related keys) or where the key users may cease to have authority (e.g., terminated employees). key management protocol A protocol developed to facilitate establishment ofa key-administered transmission between entities wishing to secure the communication through key encryption. key recovery The process ofdetermining the value of a cryptographic key that has been used to perform an encryption operation. Key recovery is a hotly debated political topic since law enforcement agencies have desired and at times secured the legal and technological capability to recover keys for decrypting secured communications. A key "escrow" system that included portions of keys (to facilitate key recovery) was at one time intended to be associated with software products exported out of the U. S. Key recovery by governmental agencies was repeatedly proposed and defeated during the 1990s. Key encapsulation is a means of storing information about a cryptographic key by encrypting it with another key so that only authorized recovery agents may decrypt and retrieve the stored key. See key escrow. key space The universe or space from which cryptographic key values may be taken. It is the total number of distinct transformations which may be supported by a cryptographic scheme, in other words, the realm of possible variations possible. key update The updating or derivation of a new key from an existing key. Also called rekey. 557 ·····'.·.?··· .• ···.~· .•. II··· •. ·i\~· ;~:;;~ ::~- © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary are active (or pending), as in a multiline phone system, or to enable them to be seen in low-light conditions (e.g., a burglar alarm keypad). Steady illumination or various flashing speeds and patterns may be used to indicate the line or device status. key map A table that translates keyboard input values from one configuration to another, commonly used in computer software to transcribe the alphabets ofa number oflanguages. This is useful for transla- tion, alternate typing keyboard setups (e.g., Dvorak), graphics, and music applications. key numbers Telecommunications numbers of particular interest, such as the phone numbers of fre- quently called family and close friends or business associates. British Telecom (BT) has a key numbers service that can be managed on the Web. The Web portal enables customers to set up and manage the Friends & Family Key Numbers list associated with their phone accounts. This service is without charge for residential and business customers for up to ten numbers and may include up to two mobile numbers. It is likely that this type of Web access to telecommunications services will increase, just as online banking is increasing, due to its 24-hour availability and update convenience; the user doesn't have to wait to call service representatives during business hours. key performance indicator KPI. Astatistic intended to indicate effectiveness in specified key aspects which are typically industry-specific. In the telecommunications industry KPIs may comprise the frequency or duration of calls, revenue per call, purchase trends, etc. KPIs are used to plan budgets, inventory, and investment, financing, and growth strategies. Key Performance Indicator KPI. A commercial database to track mobile operators' key performance indicators such as minutes of use, chum, average revenue per user, and acquisition costs. The system was first released by EMC, a U.K. firm, in April 2000, and is incorporated into EMC World Cellular Infor- mation Services. The system computes average sta- tistics for each KPI for regions and reporting periods. key pulsing KP. A system for sending multi frequency signals from a pushbutton key telephone through a phone circuit to establish a connection. It is sometimes called key sending. In older, manually operated toll stations, pulsing was sometimes used by operators instead of dialing. Dial-operated pulse phones are on the decline, with touch tone phones replacing them. key service unit, key system unit KSU. The inter- nal electronics and logic that enable the selection of lines and other options in a key telephone system. This may be a small cabinet installed in a closet or some other area where the lines are not cluttering up the environment or causing an obstruction. See key telephone system. key station Master station from which broadcasts originate. key telephone system, key system KTS. Amultiline telephone system in which individual phones have multiple keys or buttons that the user presses to se- lect the line over which she or he wishes to commu- nicate. In larger multiline key systems, there may be 558 a main console through which the calls are channeled. This is not the same as a private branch system, in which a separate switching system is associated with the phones. In the key system, which is used in many small offices, the switching and selection of lines is done manually by the user. Some larger offices with private branch exchanges will use a hybrid system which also incorporates one or more key systems, sometimes in individual departments. New key systems commonly feature programmable function keys and LED status displays. See key service unit, private branch exchange. keyboard A hardware peripheral interface device for detecting and transmitting user input to a computer- ized system through keys with assigned functional values. Descended from typewriter keyboards and typically arranged according to the historic "QWERTY" typewriter layout which, ironically, was designed to slow down typing in order to prevent key jamming on old manual typewriters. A variety ofkeyboard layouts and shapes are available for various computer systems, some with better ergonomics than those which typically come with the system. See keypad; keyboard, touch-sensitive. keyboard buffer Recent input is typically stored in temporary memory in order to prevent loss or cor- ruption in the event that the system was not yet ready to respond at the time that the keys were pressed. keyboarding Striking keys on a computer or other digital keyboard. This is distinct from typing in that typing is generally intended to immediately translate the keystroke into an image on a printing surface. Keyboarding, on the other hand, enables the keystroke to be stored and manipulated for a variety of purposes, including word processing, chatting, sig- nalin~, or printing at a later time. It is possible to "type' on a computer keyboard with a software program designed to immediately send the key to a printing device, but this is rarely used due to the greater convenience ofediting the keyboard strokes before printing (or sending them electronically without printing). keying A means ofmodulating a signal. This can be done in anumber of ways, by varying the amplitude, frequency, or phase ofa signal. See amplitude shift keying, frequency shift keying, Gaussian minimum shift keying, quadrature phase shift keying, phase shift keying. keypad A key-based physical interface for various calculators, dedicated word processors, security systems, and computing devices. It is usually a compact group of functionally related keys, often consisting of numbers aligned in rows and columns to facilitate finger access. Alarger grouping, as on computers or typewriters, is usually called a keyboard. On a calculator, the keypad is generally configured as three or four columns by five or six rows, depending upon how many extra function keys (memory, clear, print, etc.) are integrated into the key pad layout. Many security entry devices and alarm systems are managed through a keypad with nine or twelve keys for entering numeric codes or alphanumeric © 2003 by CRC Press LLC passwords. The system may be wired or wireless and may trigger other mechanisms (e.g., a security camera) if used or if suspicious codes are entered. See keyboard, numeric keypad. keysheetAn administrative plan for phone extensions that tracks and illustrates the connections and features assigned to that phone. Keysheets are practical in in- stitutional environments with many extensions, par- ticularly if the extension phones have different capa- bilities and dialing privileges. Akeysheet is even more important for keeping track if the phones are also individually programmable or if they are relo- cated on a regular basis. Software exists for developing keysheet connection plans, diagrams, and overlays. Electronic forms are now also commonly used for individual members of departments to list the phones, faxes, and modems for inclusion in a keysheet database. keystoning A visual aberration which occurs when an image is projected on a surface off-plane, that is, on a surface which is at an angle to the plane of the surface of the projecting lens. Thus, ifa rectangular image from a film or slide projector, for example, were projected on a movable screen which was crooked, the image would be wide on one side and narrow on the other. See barrel distortion. kHz abbrev. kilohertz, 1000 hertz. See hertz. kiddie cam A video camera installed to monitor the activities of children, often over a network. These are common in household nurseries and increasingly common in daycare facilities. Some of these cams have been interfaced with the Internet to enable par- ents and caregivers to remotely monitor the activities of children. For the safety and privacy of children being monitored by Web-based kiddie cams, some kiddie cam services require a password to login to the remote viewing site. Unfortunately, the kiddie cam moniker is also used by some sites to promote pornographic images of girls and boys who have been covertly photographed or who are too young to understand how their image is being used. This type ofexploitation is generally illegal, but the sites promoting child pornography manage to stay online long enough for the images to be downloaded and shared among thousands or millions of Internet users. KIF See Knowledge Interchange Format. Kilby, Jack St. Clair (1923- ) An American inventor and Texas Instruments Incorporated (TI) em- ployee who was involved in designing the first integrated circuit chip, shortly after joining TI. The development catapulted the miniaturization and speed of electronics into a new level of evolution. Kilby's first IC was introduced in September 1958, shortly before Fairchild engineers developed historic ICs that were, for some time, considered to be the fIrst (the patent was awarded to Noyce even as Kilby's application was still being assessed). Texas Instruments has named the Kilby Center, a silicon manufacturing research facility, in his honor. Kilby is also responsible for providing miniaturized electronics that supported the portable calculator market and off-Earth electronic devices that needed to be small and sparing on power consumption. In October 2000, Kilby's contributions were acknowledged with a Nobel Prize in physics jointly with two other scientists. See integrated circuit; Noyce, Rob- ert; transistor. KiidaU, Gary (1942-1994) American educator and pioneer software developer. Kildall developed CP/M (Control Program/Monitor) over a number of years, beginning in 1973, with contributions from his stu- dents, when he was a professor of computer science at a California naval school. Kildall developed CP/M into a popular, widely used, text-oriented, 8-bit operating system in the late 1970s. Kildalllater founded InterGalactic Digital Research, which became Digital Research (DR), to market his software products. Digital Research developed GEM, an early graphical user operating system which pre- dated functional versions of Windows. DR also created DR-DOS, which was competitive with MS- DOS, and claimed by many to be superior . Kildall is also known for developing PLIM prior to CP/M, the first programming language for the historic Intel 4004 chip, and for co-authoring a floppy controller interface in 1973 with John Torode. In the ensuing years, Gary Kildalliost one political battle after another with the rapidly expanding Micro- soft, and Digital Research never flourished as one might expect for a company so often in the forefront of technology. Digital Research had a history of creating good products, but was overshadowed by its larger, more aggressive competitor. At one point DR won a lawsuit against Microsoft, but it may have been a case of too little too late; at that point Microsoft had so much momentum, it was unlikely Kildall and DR could regain their market share. Kildall is acknowledged as the original developer of many significant technologies for the microcomputer industry, but unfortunate circumstances cut short his life at 52. See CP/M; Gates, William. kill 1. Remove or delete, as a word, line, or file. 2. Abruptly or prematurely terminate a process or broadcast. kill file 1. An email or newsgroup filter that sends messages from particular people, or on particular top- ics, to the "bit bucket," that is, they are shuffled off to a file that never gets read, or is deleted unread. 2. A list of users banned or otherwise controlled from access to remote terminals or online chat seIVices. See kill command. kill command A software control command available to operators on various chat systems to discon- nect a disruptive member from the site. Common reasons for killing a user include racial, cultural, or reli- gious slurs, violation of chat rules, illegal activities, or excessive profanity. On Internet Relay Chat (IRC) there is a general set of guidelines and a code of eti- quette to guide channel operators in the appropriate use of the IRC /kill command. kill message 1. A textual message transmitted by an operator to a user in a computer-based "chat room" who is in the process of being removed from the chat 559 . "' '." .•••• : .• " "g~l" ' ::~~ :1 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary area. This is an option on most systems for operators to inform the user as to why he or she is being removed. See kill command. 2. A software command sent to stop a process. This may be on a single-user system, a network, or a specialized system such as a Iransaction system based on digital data cards. A kill message can halt a process that has hung or gotten out of conlrol, without taking down the operating system; it can stop suspect activities (e.g., possible hacking) on a network with remote terminals, or it can stop the use ofa suspected stolen or lost ATM card. 3. An introductory message played over a telephone connection when the user has called a local or long-distance pay-per-call service. It may include consumer protection information or specifics about restrictions or potential call costs. Calls that may ex- ceed charges ofa specified amount may be required to include a kill message in the first few seconds of the call to allow the caller to hang up before charges accrue. In spite of mandatory preambles and kill messages, there were complaints to and by the Federal Trade Commission (FTC) in the mid-1990s that telephone service vendors were abusing so-called toll-free 1-800 numbers in a variety of ways, including for- warding 1-800 calls to 1-900 numbers or otherwise manipulating the system to rack up charges on the callers' phone bills. KILL message I. A software message that causes a client/server connection to be closed by the related server for a variety of reasons, depending upon the system. For example, in Internet Relay Chat, it may be automatically invoked when duplicate nickname entries are detected; both entries are removed with the expectation that only a single nickname will re- appear. This maintains global uniqueness. The KILL message may be available to operators but ideally should be handled by servers. See RFC 1459. kilo- (abbrev. - k or K) Prefix for one thousand (1000), or JOl. 10 kilograms = 10,000 grams when used for weights and measures. When used in the context of computer data, more commonly it is capital- ized, as in Kbps (kilobits per second), and represents 1024. See k, K. kilocharacter One thousand characters. See kilosegment. kilosegment One thousand segments, with each seg- ment consisting of up to 64 characters. It is used as a billing measure in some systems, such as X.25. kilovolt-ampere kVA. A unit of apparent power. This is a general measure of power consumption for nonresistive devices such as certain types oflighting and computer components. kilowatt kW. An SI unit of power required to do work at the rate of 1000 joules per second. See joule, kilowatt-hour, watt. kilowatt-hour kW-hr. A unit of the energy used to perform work as measured over a I-hour unit of time. One thousand watt-hours, or 3.6 million joules. This has practical applications as adescription of the efficiency of different types of fuel, which can be expressed and compared in terms ofkilowatt-hours. 560 kinescope I. A cathode-ray tube (CRT) in which electrical signals, as from a television receiver, are dis- played to a screen. 2. An early term for a motion picture, and probably the inspiration for the term cinemascope. In Britain, the term cinematograph was used to indicate a motion picture or motion picture camera. kinetograph A device patented in 1889 by Thomas Edison for photographing motion picture sequences. See kinetoscope. kinetoscope Adevice patented in 1893 by Thomas Edison for viewing a sequence of pictures, based upon the work of earlier experimenters going back as far as 1883. The loop of film images was illuminated from behind and viewed through a rapidly ro- tating shutter, thus creating a small motion picture film. See kinetograph. King, Jan The young engineer who coordinated a number ofsignificant amateur radio telecommunications satellite projects, starting with Australis-OS- CAR 5 and continuing with the AMSAT satellites. King has written articles and technical reports on some of these activities, many of them for the QST journal. See AM S AT, OSCAR. Kingsbury Commitment An important event on December 13, 1913 in which the U.S. Attorney Gen- eral, James McReynolds, informed AT&T of viola- tions of the Sherman Antitrust Act of 1890. AT&T voluntarily gave up controlling interest in the West- ern Union Telegraph Company, and agreed to stop buying up the independent telephone companies without first obtaining approval from the Interstate Commerce Commission (ICC). AT&T further agreed to provide independent phone companies with access to the long-distance network. The Kingsbury Commitment derives its name from Nathan C. Kingsbury, the AT&T vice president who was appointed by Theodore Vail to correspond with the Attorney General. It is sometimes colloquially called the Kingsbury compromise. See Modified Fi- nal Judgment. Kirchhoff, Gustav Robert (1824-1887) A German physicist who conducted pioneer work in spectros- copy and followed up on Ohm's work by providing further information and a more advanced theory of the flow of electricity through conductors. He also made adjustments to Huygen and Fresnel's description of the behavior ofwavefronts by introducing the obliquity factor. See Huygen's integral, Kirchhoff's laws. Kirchhoff's laws Laws for the flow ofcurrent first described in 1848 by G.R. Kirchhoff: I. The current flowing to a given point (node) in a circuit is equal to the current flowing away from that point. 2. In any closed path in a circuit, the algebraic sum of the voltage drops equals the algebraic sum of the eleclromotive forces in that path. KIS See Knowbot Information Service. KISS Keep It Simple Stupid. Atongue-in-cheek, but all-too-relevant design and management philosophy. © 2003 by CRC Press LLC Google is an excellent search engine on the Internet whose success is, in part, due to the relative absence of bells and whistles. The early Apple Macintosh computers held to this philosophy as well, developing a one-button mouse when many others were using mice with two or three buttons, and maintaining standards for the operating system that enabled new users to quickly figure out how to use it. KISS method A system-independent architecture related to information systems modeling, which is described in terms ofobject-oriented concepts by its author, Gerald Kristen. KISS concepts are presented in a series of stages, and the model and presentation are sufficiently different from other works in the field of object-oriented (00) programming that it has not excited a lot of interest in the 00 programmers' com- munity. KittyhawkA line of very small-sized (less than 2 x 3 in.) 20- and 40-MByte, 44-pin IDE hard drives distributed by Hewlett Packard for use in palmtop text and PDA computers. KLAS-TV An early commercial adopter ofall-dig i- tal advanced television (ATV) technology. KLAS- TV is a Las Vegas CBC affiliated owned by Landmark Communications, Inc., a privately held media company. Advanced television technologies were researched in the early 1990s by the Advisory Com- mittee on Advanced Television Service (ACATS), with digital technologies coming in late in the process, but then becoming the central focus of ACATS evaluations. The ACATS Final Report was presented in 1995, paving the way for broadcast stations in North America to begin to implement higher quality, standardized digital television services. KLAS- TV was the first broadcaster in the Las Vegas region to offer end-to-end digital technology and transmissions, in April 2000. Prior to offering digital subscriber services, KLAS- TV delivered digital programming 2 years in a row to the National Associa- tion of Broadcasters (NAB) annual trade show at a Las Vegas convention center, establishing themselves as one of the pioneer commercial providers of all- digital broadcast programming. System components for KLAS- TV equipment were developed and provided by Harris Broadcast Com- munications, who also provided the radio frequency Test Bed used in the ACATS evaluation of prototype digital broadcast systems. See Advisory Committee on Advanced Television Service, Harris Broadcast Communications. Kleinrock, Leonard (1934- ) In 1976, authored Queueing Systems Volume II - Computer Applica- tions, a publication which helped the spread and ac- ceptance ofpacket-switching technology. Kleist, Ewald Christian von See von Kleist, Ewald Christian. kludge, kluge Patchwork, improvised, or makeshift hardware or software, which can result from (1) time or material constraints, (2) sloppy workmanship, lack of foresight, (3) communication problems between decision-makers and implementors, or (4) staff changes or design changes during a proj ecl. Kludge usually has a negative connotation, especially with software that tends to be sluggish from lack of structure and optimization, while well-conceived, but time-constrained projects are more often called "quick-and-dirty." Even well-begun projects can become kludgy after awhile, in which case engineers will generally advise, "Time for a ground-up rewrite!" Klystron, klystron From the Greek "klyzo."A high- vacuum electron tube that uses electric fields to cause the "bunching" of electrons into a well-focused beam. The beam's kinetic energy is converted and ampli- fied into ultra-high frequency radio waves (micro- waves). Klystron was established as a trademark and as such is spelled with a capital letter, though the term is now also used generically for the historic line of Klystron tubes. Klystrons were used widely as oscil- lators and applied to radar transmitters until they were superseded for some applications by cavity magne- trons. Current commercial tubes are long-life, reliable, remanufacturable components. Klystron Electron-Tube Inventors '. Top: The Klystron and its inventors at Stanford in 1939. Clockwise from the left are Sigurd Varian, David Webster, William Hansen, John Woodyard (a gradu- ate student), andRussell Varian. SmallKlystrons were usedfor radar, navigation, and communications applications. [Copyright 1939 and 1951 StanfordNews Service archives; used with permission.] The Klystron evolved from pioneer versions of the magnetron which were developed in the 1920s. Russell H. Varian and Sigurd F. Varian respectively designed and constructed the first Klystron prototype at Stanford, beginning in 1937, in collaboration with William Hansen. The July 1937 notes of Russell Varian describe the "Rumbatron Oscillator or Ampli- fier" and input from William Hansen regarding a "spherical rumbatron with one core reaching to the center." The rumbatron moniker was based upon Hansen's previous work on cavity resonators. The Varians combined this with principles of velocity modulation to create the Klystron, publicly announced in 1939. 561 © 2003 by CRC Press LLC . Fiber Optics Illustrated Dictionary Kalman filter. The discrete Kalman filter (DKF) at- tempts to estimate the state ofa discrete-time-controlled process. The extended Kalman filter (EKF) handles nonlinear situations by linearizing (e.g., with partial. whether or not to ignore re- transmitted signals. It is also applied to backofftim- ers in Point-to-Point (PPP) tunneling networks. See ATM, Jacobson's algorithm, Point-to-Point Tunnel- ing Protocol. Kawakami,. a few inches apart. A piv- oting beam balance enabled a set of rings to move 553 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary freely between the coils. Afinely incremented ruler- like