Fiber Optics Illustrated Dictionary - Part 66 pptx

Fiber Optics Illustrated Dictionary telecommunications service providers, MIDP is a set of Sun JavaAPIs that is part of the J2ME application runtime environment for mobile information devices, along with the Connected Limited Device Configu- ration (CLDC). MillP was developed through the Java Community Process. It specifies aspects of storage, application life cycle, networking, and user in- teraction. MIDP for PalmOS is an implementation of CLDC and MIDP optimized for PalmOS handheld platforms. Mobile IP, Mobile Internet Protocol Mobile data networking through the Internet is coming into demand as the number of laptops and the availability of wireless modem services increases. Since the problems ofmaintaining contact with anetwork and network security are concerns on mobile systems, a set of extensions to Internet Protocol (IP) is being developed to handle the special needs of mobile users. Mobile IP uses a dual addressing scheme so that the communications node and the mobile unit can be tracked and administered. In simple terms, the location of the mobile system becomes a forwarding address to which packets are retransmitted. Security is incorporated to prevent an unauthorized person from intercepting the transmission. See Foreign Agent. Mobile Management Forum MMF. A forum of the Open Group, announced in May 2000, as a means to pursue the objectives of the Open Group Wireless and Mobile Program. The MMF supports and promotes the deployment of interoperable wireless applications and devices into enterprise environments. http://www.opengroup.orglmobile/ Mobile Maritime Committee MMC. An informal committee of the U.S. Coast Guard that has existed for some time to express and address local maritime issues and problems. In February 2000, a more for- mal organization was established to promote actions to improve the safety, security, mobility, and environ- mental protection of the Mobile, Alabama, port. Members consist of port and waterway users and regulatory agencies. See Marine Safety Office. Mobile Meteorological Equipment MME. Through the work of the Ad Hoc Group for Mobile Meteoro- logical Equipment (AHGIMME), the Federal Direc- tory of Mobile Meteorological Equipment and Ca- pabilities was prepared to assist agencies in individual responsibilities and planning activities in response to requirements and emergencies. The Directory cata- logs mobile meteorological equipment, software, and capabilities of U.S. federal departments and agencies to facilitate interagency cooperation. The Department of Defense (DoD) has been particularly active in the development and deployment of mobile systems. Mobile Multimedia Communication project MMC project. Amultidisciplinary research project coordinated within Delft University of Technology in the Netherlands. The MMC project was established to research solutions to wired and wireless Internet-style applications and bandwidth applications as they can be adapted to mobile networks such as cellular systems. The project ran from April 1996 to September 2000. Some of the work in the project has been trans- 642 ferred to the UbiCom (Ubiquitous Communication) program. Mobile Network Location Protocol MNLP. In CDPD mobile communications, the MNLP provides a means to track the Mobile End System (M-ES), that is, the laptop modem, cellular phone, or other device that allows the user to link into the network, and to interlink the Home Mobile Data Intermediate System (MD-IS) and the Serving MD-IS. This works in conjunction with a Mobile Network Registration Proto- col (MNRP) to verify the user's Network Entity Iden- tifier (NEI), a security ill used to monitor and con- fine service to authorized users. Mobile Network Registration Protocol MNRP. See Mobile Network Location Protocol. mobile phone An audio broadcast system designed to provide mobile communications through hardware interfaces resembling traditional phone handsets. The earliest mobile phone systems were bulky, limited contrivances developed after the tum of the century and first demonstrated in 19 19, but they were ac- knowledged as having an important place in future communications. Historically similar to broadcast TV, a powerful transmitter was located to provide maximum range, up to perhaps 30 miles, for traveling subscribers. To in- crease the limited range and channel distribution of the single tower design, cellular networks were developed, which increased available bandwidth by providing many lower power transmitters, closely located to one another, over a wide geographic region. There are now a number of types of mobile phones, from short-range FM cordless phones with a range ofa few hundred feet, to digital PCS and cellular systems with roaming capabilities that range from hundreds to thousands of miles. See cellular phone. Mobile Solutions Partner Program MSPP. A Microsoft program initiated in August 2000 to promote development of mobile communications solutions based on .Net Mobile Web technology. MSPP supports vendors who are developing for the Micro- soft Pocket PC operating system. The program was initiated in part as a competitive response to Palm's business lead in the mobile communications industry. Mobile Subscriber Unit MSU. A main component ofa mobile phone system consisting ofaportable or transportable control unit and cellular radio transceiver. Convenience, size, transceiver power, and battery life are traded off in the various systems. Larger, more powerful units may be mounted to car batteries, and often split the telephone and the hand- set into separate units. Smaller handhelds frequently have less range and shorter battery life. See cellular phone, mobile phone. Mobile Telephone Switching Office MTSO. A main component of a mobile phone service, which per- forms wireless relaying, switching, and administration tasks similar to those carried out by a wired telephone switching office, except that it must handle the specific technical needs of users who are moving and roaming (changing from one transceiving area to another) with signal monitoring and processing, © 2003 by CRC Press LLC handoffs, etc. In addition, the MTSO handles the link between the mobile services and connections to wireline services, as many mobile services are actually hybrid technologies, often taking calls from mobile users and connecting them with a wireline destina- tion, and vice versa. Mobilization Against Terrorism Act MATA. See Anti-Terrorism Act of2001. Mockapetris, Paul The developer of the JEEVES DNS Resolver, the first implementation of the Do- main Name System, now incorporated into the Inter- net. Mockapetris is responsible for a number of significant Request for Comments documents related to the development of the Internet. His DNS Resolver spawned several subsequent implementations, the most significant being the Berkeley Internet Name Domain (BIND). In June 2001, Mockapetris was announced as Chairman of the Board for Nominum, Inc., a naming and address management solutions provider. See JEEVES DNS Resolver. modal In applications programming, a type of user window, dialog, or other input or information display operation which does not suspend access to other pro- cesses. For example, suppose the user has selected a Quit function, and the software displays a dialog box that says,- "Do you really want to quit? If so, the program will end without saving." Options to Quit or to Cancel will be presented. If the dialog allows the user to go back to the application without responding to the Quit/Cancel query, the operation is modal. If the user must reply before continuing with using the software, then it is not. While modal (multitasked) op- erations are preferred in many situations, in others, a response should be solicited before continuing, especially if it involves the possible loss of data. mode In some older operating systems, adistinction was made between text mode and graphics mode, but most systems now work in graphics mode with text represented graphically. This system is more flexible. modem modulator/demodulator. 1. A device which modulates and demodulates a signal. Digital data are typically modulated to be carried over analog transmission systems, and broadcast waves are modulated to add infonnation to the carrier band. These are then demodulated again at the receiving end. 2. A computer hardware peripheral specifically designed to convert the digital signals generated by the computer into analog systems that can be carried across an analog transmissions medium such as twisted-pair cop- per wire, and demodulate them back into digital data at the receiving end. Many standards exist for the transmission of this type of data, and the sending and receiving modems must be able to negotiate a common format in order for the signals to be meaning- fully received. Current modems commonly transmit at rates of 19,200 bps, 38,400 bps, and higher; most include facsimile transmission capabilities, and some include voice mail capabilities as well. They incor- porate a number of error control, data compression, and modulation protocols in order to maximize speed of transmission over lines that people once claimed could never transmit data faster than 600 bps. See error control protocol, data compression protocol, modulation protocol, serial port. modem pool A set of modems usually servicing a network through which several users can dial out of the system, or through which a number of users can dial in, as to a BBS or Internet Services Provider (ISP). Most higher educational institutions have modem pools for users to access the system from home or classrooms, or through which they can dial out to community services or extra service providers. Of- ten the modems in a pool will have different characteristics. For example, only a few lines may be high speed lines, due to higher cost, and the remainder may be a variety of slower, less expensive modems. Some modem pools are extremely large. For example, one of the largest commercial Internet providers has over 100,000 modems in its pool. A pool is a flexible way to maximize resources. A dozen modems can service a hundred workstations, provided the users do not need constant access to dialup resources. It is also easier for system admin- istrators to carry out hardware maintenance and to maintain security when the modems are grouped and placed in a secure environment. Modems Two different computermodems: the Global Village on the left has a built-in 9-pin DIN connector, and operates at 33,600 bps; the SuperModern on the right has a standard 25-pin connection supporting V:34 standards. Each can be connected (daisy-chained) with a regular telephone set. modem serverA networked workstation application which manages the administrative and access tasks associated with a modem pool, or an intelligent modem hub which manages incoming and outgoing data from more than one user. In large modem pools, a system may be dedicated to assigning user requests for modems, for sending messages to the user (e.g., "All systems are currently busy, please make your request again in 15 minutes."), for evaluating which modems to allocate first (there may be different modems with different capabilities, such as access speed), and for assigning priorities and connect times, when appropriate. modem standards This is one of the areas where de 643 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary facto vendor standards and industry standards (e.g., lTD-TV Series Recommendations) have continually leapfrogged one another, and engaged in an uneasy competitive race. The constant consumer demand for faster modems and the vendor desire to be the first to market with the next generation modem, have caused many vendors to develop their own standards ahead of the global cooperative standards process. For this reason, many modems are dual-standard modems, in order to support both the vendor and gener- ally accepted industry standards. Some modems support either vendor or industry standards, which are often not compatible, and it is important to find out their status before purchasing. In many cases, the early versions of modems supporting the faster speeds are the ones most likely to go out of date quickly. In the early days, many vendors followed Bell and Hayes standards, whereas in re- cent years, vendors have tended to go with the industry standards once the specifications are finalized and made available. The Hayes command set remains, although most vendors implement a superset of the original Hayes commands, which were quite simple and limited. The Microcom Network Protocol standards for error control and data compression are widely supported modem standards. See Microcom Networking Pro- tocol, V Series Recommendations. modifed chemical vapor deposition MCVD. See vapor deposition. Modified Final Judgment, Modification of Final Judgment MFJ. The name given to ahistoric 7-year antitrust lawsuit between the U.S. Justice Department and AT&T, which resulted in the breakup of AT&T. It is associated with Judge Harold Greene's decision regarding the 1983 to 1984 (clarification and revision) divestiture of AT&T. Under this judgment, AT &Twas permitted to retain ownership of Bell Laboratories and AT&T Technologies (Western Electric), but the Regional Bell Operating Companies (RBOCs) were banned from manufacturing, and Local Access Trans- port Areas (LATAs) were created rather than retaining the existing local exchange boundaries. Prior to the MFJ, charges were handled through Di- vision of Revenues, but this was changed to an access charge tariff system. See AT&T; Greene, Harold; Kingsbury Commitment; Local Exchange Carrier; Willis Graham Act of 1921. Modified Huffman MH. Huffman is a variable- length, tree-oriented data encoding scheme that op- timizes on the basis of more frequently occurring characters in order to achieve compression in fewer bits. Modified Huffman is widely used in facsimile transmissions. See Huffman encoding. modular Composed ofseparately organized entities, loosely or tightly coordinated or connected to create a larger whole. Modular programming is programming in which the larger application is composed of smaller associated elements such as blocks, objects, primitives, self-contained functions, etc. Object- oriented programming is a type of modular programming. A modular office is one in which the individual 644 components of the facilities can be changed around fairly easily; that is, desks, screens, phones, cables, etc. can be rearranged without undue effort. A modular phone system is one in which handsets or phone sets can be unplugged and moved or rearranged within a building or department. Modular software is software in which a number ofseparate or related utilities, tools, and functions can be used together in a number of ways. For example, there may be avari- ety offunctions that do file conversions, image processing, filtering, special effects, etc. which can be used separately or in conjunction with a variety of programs. Some of the more flexible, stand-alone "plugins" exhibit these properties of modularity. For example, there may be awatercolor plugin which can be used independently to alter the contents ofa graphics file, or may work as a plugin in the context of several programs such as an image processing program, a drawing program, etc. modular multi-satellite preprocessor MMSP. A frame synchronizer designed to provide an interface between a host computer and synchronized mapper telemetry data. The MMSP takes the raw telemetry data, frame aligns and samples it, and transmits the information to the host computer, where it is further processed and the image information extracted from the data. modulate To change gradually from one state to another. To tune or adjust. To vary the amplitude, frequency, or phase, typically to add information to a carrier wave. To change the velocity ofelectrons in an electron beam, as in a cathode-ray tube. modulation A key element in the transmission of information. By changing or modulating an electrical pulse through a wire or other conducting medium, or an airborne electromagnetic wave, it is possible to convey information. Similarly, by manipulating its intensity and duration, light can be modulated to send information. Some of the simplest forms ofmodula- tion include turning a signal on or off, or varying it between high and low states. F or computer users, one of the most familiar modulating devices is the dialup modem, which takes a digital signal from the computer and modulates it to be carried over analog phone lines. At the receiving end, a modem then demodulates the signal, turning it back into digital signals that are transferred to the receiving computer. There are many modulation techniques used through- out the telecommunications industry, some very simple, and some so sophisticated only computers can control them. The most common types of modulation are amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). Sometimes different modulation schemes are combined. Each scheme has its own unique characteristics. Early detractors said frequency modulation was math- ematically impossible, but Edwin Armstrong demonstrated, after 10 years of hard research applied to the problem, not only that it could be done, but also that it was a great thing. It has since been used in thousands ofapplications from radio programming to cordless © 2003 by CRC Press LLC phones and burglar alann systems. Another important contribution to modulation was the work of John R. Carson, who demonstrated how a portion of a modulated signal could be transmitted, instead of the whole thing, and the original signal rebuilt at the receiving end, thus reducing bandwidth without loss of information. See amplitude modulation; Annstrong, Edwin; frequency modulation; phase shift keying; quadrature amplitude modulation; sigma-delta modulation; single sideband. modulation protocolA data encoding technique used to convert digital data into analog signals. This de- termines the raw (uncompressed) speed at which the modem can transfer data. Current modems incorpo- rate more than one protocol. See modem. modulation, light A means of conveying information by manipulating a beam of light. The light can be directly influenced, by turning it on or off, or varying its intensity; it can be indirectly influenced by interposing shutters, gels, or other objects between the sender and the receiver. Light modulation is used in fiber optic transmissions, with lasers and light- emitting diodes used as common light sources. moire 1. In raster-oriented imagery, moire is a visual artifact that appears as an undesirable, distracting secondary pattern which disturbs the intended appearance of the image. 2. In traditional printing on a press, especially process color printing, small dots are often interleaved to simulate the appearance of more colors. If the angles and patterns of these dots are not carefully controlled, a moire pattern, resembling light through silk, may emerge. Better desktop publishing programs provide print settings to set the angle and type of halftone to match the technology on which the job is printed. 3. In video images, mixing high frequencies can create an undesirable, visible, low- frequency moire. moisture barrier A cover, sheet, bag, or other barrier, usually plastic, intended to retard or prevent moisture from coming in contact with building structures, wires, or electrical components. Moisture bar- riers are used to prevent rot, condensation, and electrical short circuits. MOKE magneto-optic Kerr effect. See Kerr effect. molding raceway A channel system incorporated into wood, plastic, or metal moldings to hold, pro- tect, and direct interior wiring circuits. Molding raceways are of modular construction with a variety of fittings, so individual sections can be interconnected and holes can be punched where needed. Molding raceways are commonly used on baseboards and wainscots, where they blend naturally with the de- cor. See raceway. Monolithic Microwave Integrated Circuit MMIC. Analog circuits incorporating a number of integrated functions operating at microwave frequencies. Many types ofMMICs can be purchased for $5 or less per chip. MMICs provide support for wireless communications technologies, making it possible to design low-cost, high-bandwidth data transmissions links. MMICs can be used to convert between baseband and modulated microwave signals and, as such, can be used in conjunction with traditional integrated circuits (lCs) handling the baseband signals. MMIC arrays developed by the NASA/Lewis Re- search Center and the Air Force Rome Laboratory were demonstrated in the mid-l 990s in conjunction with NASAAdvanced Communications Technology Satellite (ACTS) technology. These proof-of-concept MMIC arrays were in the KIKa-band frequencies, Radio Frequency Transmission Schemes Format Abbrev. Notes ALOHA A free-for-all style of transmission; any source transmits at any time, and continues to transmit if there is an acknowledgment. It is not a high- efficiency method, but there are circumstances where it is practical. Code Division Multiple Access CDMA A hybrid scheme which incorporates time/ frequency multiplexing to provide spread spectrum modulation. Thus, central channels can be handled without timing synchronization. Frequency Division Multiple Access FDMA A traditional method of channel allocation in which bandwidth is subdivided into frequency bands, with guard bands providing a buffer between channels. Packet Reservation Multiple Access PRMA A type of enhanced TDMA which incorporates aspects of S-ALOHA. Suitable for mobile transmissions. 645 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary indicating that high-density MMIC integration at 20 and 30 GHz was feasible. Once MMICs became commercially available, they began to be ofinterest for many types ofcommercial and scientific applications. The Search for Extrater- restrial Intelligence (SETI) League, for example, con- siders the technology useful for constructing research devices for space communications and the possible interception of communications emanating from other regions of the Universe. The Wireless Systems Innovation lab of NTT has developed uniplanar and multi planar MMICs more compact and less expensive than earlier technologies that are suitable for radio, wireless area networks (WANs), and satellite transponders. With MMICs incorporated into beam-forming networks, it is en- visaged that Earth station satellite terminals can be designed to be as small as cellular telephones. monopole A slender self-supporting tower for attach- ing wireless antennas/aerials. Moonbounce, Earth-Moon-Earth bounce EME. A means of using the Moon as a passive reflector for communications signals. Due to the great distances involved, very large antennas and strong signals are required, but given these in conjunction with the right weather conditions, Moonbounce transmissions have been demonstrated. The first Moonbounced signal was recorded in J anu- ary 1946 in New Jersey, where army engineers used a recently invented FM transmitter and receiver developed by E.H. Armstrong to send pulses to the Moon, which returned as a slight hum. This was a significant achievement as it not only showed the potential ofFM broadcasts, but also demonstrated that radio waves could pass through the ionosphere and beyond. Gordon E. Moore -Intel Founder Gordon E. Moore, cofounder of III tel Corporation not only cofounded and headed up one of the most successful computer chip companies in the world, but is also well rememberedfor hispredictions aboutsemi- conductor evolution now encapsulated as "Moore's law. " [Photo copyright Intel Corporation; used according to Illtel Press Room conditions.} 646 Moore, Gordon E. (1929- ) An American chemist and business executive, Moore cofounded Fairchild Semiconductor, then Intel Corporation, in 1968, along with Robert Noyce, one of the inventors ofintegrated circuit technology (1959). In 1975, Moore became President and CEO until elected chairman and CEO in 1979. He retained the position of CEO until 1987 and became chairman emeritus in 1997. In May 2001, Moore retired from the board, having reached the age at which he had set mandatory retirement from the corporation. Moore is afellow ofthe IEEE Society and Chairman of the Board of Trustees of the California Institute of Technology. He was awarded the National Medal of Technology in 1990. See Intel Corporation; Moore's law; Noyce, Robert. Moore's law Semiconductor chip technology will roughly double in capacity (and circuit density) about every year or so (later revised to every 2 years). This prediction, charted by Gordon E. Moore at a speech in 1965, turned out to be memorably prescient and has since been the basis for many industry planning decisions and forecasts. See Gilder's law; Moore, Gordon. monochromator A device used in spectroscopic scanning devices. For slit to fiber transmissions, cou- plers/adapters may be incorporated into the device. For fiber to fiber transmissions, off-axis paraboloi- dal mirrors may be used to eliminate aberrations and to provide a point image from a collimated beam to support high-resolution applications. The device may include multiple gratings to permit selection of the desired spectral range. Monochromators are designed to support different optical wavelengths and more than one device may be needed, depending upon the wavelength selections desired. See off-axis parabo- loidal. Morse code A system of character encoding using dots and dashes, or long and short sounds or lights, that can be readily sent over distance over many types of transmission media due to its simplicity. Interna- tional Morse code (continental Morse code) and American Morse code (railroad code) have been derived from this. Morse code is flexible in that it can be sent with tones, clicks, dots and dashes, and lights, in a variety of media. In 1862, two Philadelphia inventors patented a signal light system using a shuttered oil lamp for sending Morse code which was intended to be mounted on the masthead of ships. International Morse code developed from Austro- Germanic code, a variation on Morse code used in radio transmissions partly because American Morse code, while suitable for telegraph communications, was more difficult to interpret over radio waves. In 1851 it became the code of choice for transatlantic cable communications. Basic skill in Morse code has been a requirement of receiving amateur radio licenses for many decades. The code was apparently developed by Morse's collaborator, Alfred Vail, and is named for the inventor of the printing telegraph, Samuel F.B. Morse. See Morse code history. © 2003 by CRC Press LLC Morse code history The original paper tape printing telegraph designed by Samuel Morse employed a system of numbers which were then correlated with words, according to a lookup reference. The lookup reference developed by Morse was very large and the system itself somewhat slow and cumbersome; it required the maintenance ofa reference and the somewhat arbitrary assignment of nonmnemonic code number sequences to every word. A simpler, more direct system was needed. Alfred Vail was from a family of fabricators and acted for years as assistant to and collaborator with Samuel Morse. Mechanically adept, he built many of the mechanical components designed by Morse. In the process of creating the mechanisms for the Morse printing telegraph key, Vail changed the orientation of the keying mechanism from horizontal to vertical, thus providing a more comfortable hand position. The change also resulted in a stylus which would lift up from the paper, leaving dots and dashes, rather than zigzag-shaped dips on the tape record that Morse's original mechanism produced. Vail's assistant, Baxter, reported to Franklin Pope that Vail set to work simplifying Morse's unwieldy lookup code system. Vail apparently visited local printers to analyze typesetting cases to determine the frequencies ofletter usage. Pope subsequently reported the story in 1888 in The Century: Illustrated Monthly Magazine. The code Vail developed evolved into American Morse code, and International Morse Code became a further streamlined variation. As Morse's assistant, Vail had agreed to tum over his inventions to the elder inventor. [Thanks to Karen Weiss and B. Neal McEwen for unearthing and reporting Vail's possible unacknowledged contribution to history.] Morse sounder A type of early telegraph sounding instrument, which used audible clicks to broadcast the incoming message rather than apaper tape print- out, which was slow. The sounder incorporated an electromagnet as a pole piece, mounted on a pivot- ing sounding lever with two stop positions. Releas- ing the magnet as it was energized produced the click- ing sound. The duration of the clicks represented the coded dots and dashes of the Morse code system and were interpreted aurally by the receiving operator. Typically the sounder was connected to the sending instrument with only one wire. The viability of the single wire circuit was observed by Steinheil in 1837 in Germany, and independently the following year by Morse in America. Both discovered that a second wire was not needed to complete the circuit if the two in- struments were connected through the ground, using it as the return path for the circuit. This worked even over distance. Morse, Samuel Finly Breese (1791-1872) An American artist and inventor in the 1800s chiefly known for the code that bears his name. He was a re- spected artist and one of the founders of the National Academy of the Arts of Design. In the 1820s he became increasingly interested in science and invented electromechanical telegraph devices, some of the first inventions to use electricity for communication. With advice and assistance from 1. Henry and L. Gale, Morse was able to construct a basic working design for the telegraph by 1837. Samuel Morse demonstrated his invention to the presidential administration in 1838 and in 1843 won funding support from the u.S. Congress to construct a telegraph line between Baltimore and Washington, D.C. He sent his first public message over this line in May 1844, an event that launched a revolution in communications. Morse became friends with the Vail family, who were talented fabricators and were able to assist him in constructing practical working models of his ideas. Many ofMorse's inventions were built by Alfred Vail, Morse's assistant and collaborator. See Gale, Leonard D.; International Telegraph Union; telegraph; telegraph history; Vail, Alfred. Mosaic, NCSA Mosaic NCSA Mosaic is one of the most significant landmark applications in the history of the Internet as it spurred the evolution of point- and-click visual interface that nontechnical computer users, even children, could understand and quickly learn to use. The simplified Internet access and support of images provided by Mosaic and its succes- sors dramatically fueled the growth of the World Wide Web. The first version of x-mosaic was programmed at The National Center for Supercomputing Applications (NCSA) by Marc Andreessen in 1992 with Mosaic 1.0 released in November 1993. Mosaic was subsequently enhanced and ported to support the X Win- dow System, Apple Macintosh, and Microsoft Win- dows platforms. In 1994, Andreessen and other NCSA personnel left to form Mosaic Communications Corporation based on the Mosaic concept. However, due to trademark ownership by the University ofIllinois, the company and the software product were renamed Netscape Communications Corporation and Netscape Naviga- tor, respectively, with the Board of Trustees of the University ofIllinois retaining copyright ownership ofNCSA Mosaic. The University of Illinois entered into an agreement for Spyglass, Inc. to negotiate commercial NCSA Mosaic licenses in 1994. Other commercial Web browsers were in development in the mid-1990s, including OmniWeb by Light- house Design, Ltd., which was released in March 1995. In spite of the commercialization of browsers, the Software Development Group at NCSA contin- ued development on the Mosaic project until Mosaic 3.0 was released in January 1997. See Gopher, Inter- net Explorer, Netscape Navigator, OmniWeb. MOST 1. See Multidisciplinary Optical Switching Technology Center. 2. See multiplexed optical scan- ner techno logy. motion pictures Any images which, when sequen- tially displayed, convey the appearance of motion, whether in real time or by presentation ofa fast se- quential series of still pictures, especially videos, film reels, and animated computer images. Traditional motion film pictures consist of a series of still images on a transparent medium played through a 647 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary projector, usually from 20 to 30 frames per second, with 24 or 30 being common, as these are the speeds at which human perception merges successive still frames into a cohesive impression ofconnected motion. The development of motion picture photography owes some of its roots to a bet over a dispute as to whether a running horse lifted all four hoofs off the ground. Thomas Edison was one of the first to ex- periment with displaying a series of still frames in rapid succession in 1889. The first commercial motion picture, backed by the Canadian Pacific Railway, is attributed to Clifford Sutton in the early 1900s. See animation, celluloid, MPEG. Motorola Asignificant computer chip designer and manufacturer and electronic appliances manufacturer since the 1960s. It is descended from the Galvin Manufacturing Company from the early 1930s. In 1974 it released the MC6800, the first in a long family of chips still being developed a quarter of a century later. One of the first microcomputers developed with the Motorola family ofmicroprocessors was the Altair 680, released late in the fall of 1975. Since that time whole families of computers have been based on the subsequent MC68000 family of chipsets, including Macintosh, Atari, Amiga, Sun, Apollo, SGI, NeXT, and others. Motorola is also well known for products in the mobile data communications industry. The Motorola CPU Sample chart shows a brief summary of some of Motorola's best-known desktop computer microprocessors, prior to the collaboration with IBM to produce the PowerPC chips. In 1998, Motorola teamed up with the McCaw/Gates Teledesic project to provide Celestri technology to the orbiting satellite network. See Altair 680. See Sampling of Evolution of Popular Motorola CPUs chart. Mott insulator An interesting material discovered in the 1930s that appears to have the band structure of a conductor but acts, instead, as an insulator because of its energy gap characteristics. However, ifthe material is doped, it can be encouraged to behave as a high-temperature superconductors. Mott insulators have spurred closer scrutiny into band and energy gap structures to improve our understanding oftheir in- teractions and importance. When they are better un- derstood, it will be easier to predict and harness the capabilities ofpoorlyunderstood materials. The Mott insulator is named after Nobel laureate N. Mott. Mountain Bell The familiar name for the Mountain States Telephone and Telegraph Company. Mountain States Telephone and Telegraph Com- pany An early telephone company, better known as Mountain Bell, which was formed in 1911 from the merger of the Tri-State and Colorado telephone companies, and the purchase of the Rocky Mountain telephone company. mouse A hardware human interface device that re- ceives hand and finger movements and transmits them to acomputing device. They are then interpreted into actions by the operating system and applications software. The mouse is named for its basic shape, which typically consists of a palm-sized, rounded or squarish object, with one or more buttons under the fingers and a "tail," a cord that electrically connects the mouse with the computer. Mice come in various shapes and sizes: friction mice have a ball on the side that makes contact with a hard surface; optical mice Sampling of Evolution of Popular Motorola Central Processing Units (CPUs) Processor Introd. Proc. Data Bus Addr. Bus Notes MC6800 1974 8 16 Used in Altair 680. MC68000 1979 32 16 23 16 32-bit registers. Supervisor and user mode. CISC architecture. MC68010 32 16 23 Virtual memory. MC68020 1982 32 16/32 32 256-byte cache. Dynamic bus sizing. MC68030 1987 32 16/32 32 Paged MMU on processor. 16-byte burst. MC68040 1990 32 32 32 FPU, cached Harvard buses. MC68060 1994 32 32 32 Superscalar pipelined. Power-saving. The PowerPC family was created in collaboration with IBM and Apple Computer. This was a RISC- based line from the PPC 401 to 750 (G3), with speeds ranging from 20 to 500 MHz PowerPC 1994 64 64 32 From 50 to 135 MHz MPC750 (03) 1998 64 64 32 300 MHz MPC7400 (G4) 1999 64 64 32 Double-precision FPU, AltiVec instruction set. External L2 cache interface. 350 to 450 MHz. 648 © 2003 by CRC Press LLC require a grid or special pad. Laptop variations include finger pads and rollerballs, which are not strictly mice, but which employ the same basic move- ment and input concepts. mouse history The invention of the computer mouse is attributed to Doug Engelbart and is variously reported as having been invented around 1959 to 1963. By the late 1960s, Engelbart was testing a three-but:- ton mouse in conjunction with a keyset that was used in the other hand. During the early 1980s, when the Apple Lisa was being developed (the first of the Macintosh line), there were discussions at Apple as to whether to use a two- or three-button mouse. The testing and rationale supplied by Larry Tesler indi- cated a one-button mouse was completely appropriate, and the Macintosh line still works very well with this device 15 years later. The majority of competing desktop computers use two-button mice. MP See Multilink Protocol. MP3 A popular abbreviation for MPEG-l Layer 3 or MPEG-2 Layer 3. See MPEG. MPEG Motion Pictures Experts Group. A series of international standards developed by ajoint committee under the aegis of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (lEe) to facilitate the development of digital video and audio formats and decoding schemes. Leonardo Chairiglione and Hiroshi Yasuda originated the MPEG development efforts in 1988. MPEG has received widespread acceptance for the playback of digital animations. The development of media formats is somewhat de- pendent upon how the final compressed product will be used. In the case of MPEG series standards, consumer entertainment products (e.g., optical media) were taken into consideration, and thus the percep- tual characteristics of the humans who would even- tually be viewing or listening to the decoded MPEGs were factored into its development. Video and audio technologies typically require a lot of bandwidth and file space, so a large part of the MPEG effort has concentrated on decompression schemes and fast playback algorithms. The compression itself is left up to the discretion of individual vendors. MPEG is a family of standards numbered from 1 to 4, but the numbers do not necessarily indicate a pro- gression. Some changes and development for specific needs occurred on the road from MPEG-l to MPEG- 4. What the different variants have in common is that they support the compression and playback of digital audio and video data (see chart). MPEG is an asymmetric technology, based upon the use of MPEG encoders (to compress and store or transmit data) and MPEG decoders (to decompress and display data). It is asymmetric in the sense that the speed and processing power required for encoding is not necessarily the same as that needed to de- code the MPEG data stream. MPEG decoders are used to decompress and play back MPEG-based sound and videos either separately or together. The digital technology offers many appealing options for this process whether or not the MPEG video is combined with MPEG sound or with Dolby Digital sound. One of the reasons for the quick acceptance of digital videodiscs is their versatility. For example, on a DVD disc, there may be a video track, several sound tracks, and even data tracks for the display of textual commentary or subtitles. Thus, a favorite movie could be viewed several times, in its original form, in other languages, or in its original form with subtitles or other textual information. Many commercial entertainment DVDs include audio commentaries with the verbal thoughts and im- pressions of the directors and actors superimposed over the original movie (with the original soundtrack at a lower sound level in the background). This value- added means of packaging entertainment titles is one of the forces behind the quick acceptance ofMPEG- based commercial products. To be practical for the delivery of cinema-style edu- cation and entertainment programs, the playback display ofMPEG data needs to be fast, so the technology is optimized with playback in mind. Individual contributors hold a number of patents to various technologies which have been incorporated ~~~v:l~;~E~~E~~::~~~Scf~~~;na~~~:~~ II There have been several enhancements to MPEG since its introduction as shown in the MPEG Versions chart. See animation, B-frame, I-frame, JPEG, MPEG decoder, MPEG encoder, P-frame. MPEG decoder A mechanism for ''unraveling'' the data on an MPEG-encoded medium to make it ac- cessible for playback. MPEG decoders are built into DVD players, Web browser plugin applications, and a number of other consumer products. The decoder sometimes has to handle more than just the fast decompression and display of frames. Many MPEG- encoded products come with several playback options, necessitating that the decoder be coupled with human interface algorithms to enable the user to se- lect the MPEG options desired. On commercial DVDs, these algorithms are usually presented in much the same manner as application menus and buttons as are used on desktop computers. When the user selects an option, the information is used to config- ure and control the way in which the information is decoded for playback. See MPEG, MPEG encoder. MPEG encoder A mechanism for creating MPEG- format compressed data styles for storage or transmission. While the format for MPEG compression has been standardized, the algorithms and hardware systems for creating MPEG-format data have been left up to the discretion of developers. Thus, MPEG- format files can be created in a number of ways on a variety of media and developers can create the MPEG files in a way that is appropriate for their application. MPEG decoders can even be incorporated into dedicated chips, for optimal portability or optimization for the task of encoding MPEG- format files. In general, MPEG encoding seeks to minimize file sizes without significantly compromising picture 649 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary quality. This enables faster delivery of MPEG data over computer networks and makes it possible to fit more content on storage media. To accomplish these goals, a number of clever schemes for exploiting picture redundancy (where a frame is similar to a pre- ceding frame) have been developed, such as differential encoding. Differential encoding is when you analyze a series of image frames and make some assessments about their similarities and differences and then use this infonnation to remove redundancies (and thus reduce file size). Since video sequences commonly include many frames in a row with almost the same picture information (e.g., a kite fluttering against ablue sky), MPEG Versions Version Description MPEG-1 A relatively low-quality video standard initially developed for progressive video. Later adaptations also supported interlaced video but, in general, MPEG-1 has been superseded by other fonnats for applications that require higher quality video. Coding of Moving Pictures and Associated Audio for Digital Storage Media at up to about 1.5 Mbps. ISO/IEC 11172, standardized between 1993 and 1995. An optimized 1.5 Mbps bit stream for compressed video and audio, for compatibility with existing CD and DAT data rates. Non-interlaced color video is typically implemented at 352 x 240 (288 in Europe), which is relatively low resolution, as it derives from a CCIR-601 digital television standard. Replay speed is 30 frames per second (25 in Europe), fast enough for natural-looking motion. Sample precision is 8 bits. MPEG-2 A higher quality fonnat than MPEG-l and supports both progressive and interlaced video and both two-channel and multichannel (surround) sound. It is a popular format that gained fast consumer acceptance and is suitable for a variety of digital videodisc (DVD), high definition television (HDTV), and other video applications. In consumer products, MPEG-2 sound compression technologies are not always used for the audio portion of an MPEG-2 disc; sometimes Dolby Digital is substituted (or included with the others). MPEG-2 supports a variety of bit-rates and picture resolution levels. Multiple audio and video streams can be multiplexed together for recording or transmission over a network. Generic Coding of Moving Pictures and Associated Audio ISOIIEC 13818, presented in draft form in 1993. ITU-T recommendation H.262. Similar in structure to MPEG-1, the documentation includes four parts in addition to the categories discussed in MPEG-1. MPEG-2 can address very low bit-rate applications with limited bandwidth needs, and support for surround sound multichannel applications. Video resolution is typically implemented at 720 to 550 x 480, somewhat similar to computer monitors, and a frame may be either interlaced or progressive formats. MPEG':l+ MPEG-l presented at MPEG-2 resolution. Frames are de-interlaced and compressed. MPEG-3 Originally slated to support HDTV, but it was found that the MPEG-2 standards could be devised to support both DVD and HDTV and MPEG-3 was never developed. MP3 is sometimes mistaken for MPEG-3 but MP3 actually refers to either MPEG-l or MPEG-2 Layer 3 formats. Merged into MPEG-2 when it was decided that MPEG-2 syntax could be scaled to support HDTV applications. Often confused with MPEG-I/2 Layer 3 (MP3). MPEG-4 Developed to support the world of data communications over networks which are frequently shared or limited in their transmission rates. Thus, it is optimized for the world of computer networks, uses different compression techniques than the other MPEG formats, and is more appropriate for applications such as videoconferencing, whiteboarding, and streaming video rather than for high-quality optical media-based consumer entertainment applications. Very Low Bitrate Audio-Visual Coding. Launched in 1992 to develop new algorithms for providing support for a wider range of applications, and to improve efficiency. New applications include low-bitrate speech coding and interactive mobile communications. 650 © 2003 by CRC Press LLC there are opportunities to save time and storage/transmission space by encoding only those portions of the image that change from one frame or field to the next. As with many optimization schemes, differential coding comprises a tradeoff. If a series of frames must be reconstructed "on the fly," based upon areference frame, with only the differences encoded, you can- not randomly jump to any frame in the sequence in the playback process and see the full picture without some fancy footwork and fast processing in the background. The other disadvantage to differential coding is that the playback algorithm must handle the reconstruction process and the error-checking accu- rately, or errors in decoding the reference frame, from which the others are derived, would be propagated through any frames that subsequently depend upon it. To help mitigate propagation errors that could occur from frame to frame in the playback ofdifferentially encoded MPEGs, a scheme to insert the occasional full-frame picture has been developed. An intra-coded picture (I -picture) is a complete image that is inserted every few frames to stop any reference image errors from continuing for a large number of frames. How often these frames should be inserted is a matter of balancing file size and potential error levels. Since differential encoding is intended to reduce file sizes, inserting I-pictures too frequently would negate this advantage. Sometimes images are constructed based upon the previous frames, but image processing can work the other way as well. Aprediction-error picture (P-picture) is an image constructed from information taken from previous 1- or P-pictures, while a bidirection- ally encoded picture (B-picture) is one that uses later images to construct a previous image. Confused? Think ofit this way: imagine watching a video ofa car driving past a house. Most of the image stays the same from one frame to the next since the house isn't moving (assume a stationary camera photographing the scene). As the car moves past the house, however, some of the image changes. File space can be saved by encoding only the portions that change and constructing the successive frames from the information that is known rather than displaying every frame. N ow here comes the tricky part. Suppose this scene opened with the car parked in front of the house before pulling out and driving by. There's no way to construct the portion of the house obscured by the car from previous frames because the information isn't there. With bidirectional predicted/interpolated encoding, the processor can look forward, to the frames of the house that show the portions that were obscured before the car drove off-camera, and insert that information into previous frames in the encoding process. Thus, differential encoding may be used to construct the scene based upon previous and later frames. Sound complicated? It can be, which is why MPEG is an asymmetric technology. Depending upon how it's done, a significant amount ofprocessing may be required to encode a movie to fit onto a DVD, for example, and the equipment to accomplish the task may cost hundreds of thousands ofdollars, compared to a couple ofhundred dollars for the playback deck. See MPEG, MPEG decoder. MP lambda switching MPIS (note MPLS in all up- percase is used as an abbreviation for multiprotocol label switching). multiprotocollambda switching. See lambda switching. MPLS See Multiprotocol Label Switching. MPOA MultiProtocol Over ATM. A client/server protocol integration effort specified by a working group of the ATM Forum to provide direct connectivity across an ATM network between ATM hosts, legacy devices, and future network-layer protocols from different logical networks. This will enable the production of lower-latency, scalable ATM intemet- works through a standardized virtual network with fewer router hops. See Anchorage Accord, LANE, 1Pv4, Next Hop Resolution Protocol. MPOAClientAnATM term. A device which imple- ments the client side of one or more of the MPOA client/server protocols, (Le., a SCP client pr an RDP client). An MPOA Client is either an Edge Device Functional Group (EDFG) or aHost Behavior Func- tional Group (HBFG). MPOAover ATM sub-working group A group that seeks to solve some of the implementation problems associated with asynchronous transfer mode (ATM). It is integrating LAN Emulation (LANE), Next Hop Resolution Protocol (NHRP), Classical IF, multiprotocol encapsulation, and multicast address resolution in order to provide end-to-end intemetworking ATM connectivity. MPOA is a packet-oriented protocol similar to LANE. The group provides courses, support, research, documents, and systems testing services. MPOA Reference Model MultiProtocol Over ATM Reference Model. A specification approved by the ATM Forum in June 1997 for routing/switching over ATM networks. There are Internet MPOA resources (links, white papers, specifications, etc.) at the ATM Forum's site. http://www.atmfonnncorn/atmfomm/specsiapproved.html MPP See Multichannel Point-to-Point Protocol. MRI See magnetic resonance imaging. MRU maximum receive unit. MS Mobile Station. MS-CDEX A set of Microsoft DOS extensions for CD-ROM which allow MS-DOS to recognize the presence ofa CD-ROM drive and access it accord- ingly. MS-DOS Microsoft disk operating system. MS-DOS originated from a commercial text-oriented operating system developed from Tim Paterson's QDOS (which was based upon a CP/M manual according to Paterson), first released by Microsoft in 1981 to ac- company ffiM's Intel-basedmicrocomputer system. This was a somewhat different move for ffiM, as the company had often created its products in-house. But IBM was under pressure to release a successful mi- crocomputer in order to avoid being locked out of the growing market; Radio Shack at one point had almost 80% market share with its TRS-80 line. ffiM's move to look outside its own research and development 651 © 2003 by CRC Press LLC . Schemes Format Abbrev. Notes ALOHA A free-for-all style of transmission; any source transmits at any time, and continues to transmit if there is an acknowledgment. It is not a high- efficiency method, but there are circumstances where it is practical. Code Division Multiple Access CDMA A hybrid scheme which incorporates time/ frequency multiplexing to provide spread spectrum modulation. Thus, central channels can be handled without timing synchronization. Frequency Division Multiple Access FDMA A traditional method of channel allocation in which bandwidth is subdivided into frequency bands, with guard bands providing a buffer between channels. Packet Reservation Multiple Access PRMA A type of enhanced TDMA which incorporates aspects of S-ALOHA. Suitable for mobile transmissions. 645 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary indicating that high-density MMIC integration at 20 and 30 GHz was feasible. Once MMICs became commercially. used in spectroscopic scanning devices. For slit to fiber transmissions, cou- plers/adapters may be incorporated into the device. For fiber to fiber transmissions, off-axis paraboloi- dal mirrors may be used to eliminate. Associated Audio ISOIIEC 13818, presented in draft form in 1993. ITU-T recommendation H.262. Similar in structure to MPEG-1, the documentation includes four parts in addition to the categories discussed in MPEG-1. MPEG-2 can address very low bit-rate applications

Định dạng
Số trang	10
Dung lượng	1,31 MB