Fiber Optics Illustrated Dictionary Overview of Early OSCAR Satellite Projects Satellite Launch Date Technical Details Notes Phase I Satellites - Experimental, Low Orbit, Short Life Span OSCAR I 12 Dec. 1961 10 lb, beacon, 22-day orbit. Initiated by a U.S. West Coast group. Nonrechargeable batteries. U.S. Air Force launched. OSCAR II 2 Jun. 1962 Better coatings and temper- Similar to OSCAR I, but incorpora- ature control. ting improvements. OSCAR * Not launched Phase-coherent keying. Similar structurally to previous. OSCAR III 9 Mar. 1965 First relay transponder. Tracking and telemetry equipment. Solar backup. Approx. 3000 mi. range. 18-day transponder use. OSCAR IV 21 Dec. 1965 High altitude, transponder. Unplanned varying elliptical orbit. Solar, beacon, no telemetry. Two-way communication achieved. Link between Russia and U.s. OSCAR 5 23 Jan. 1970 Controllable, magnetic Seven analog telemetry channels. attitude stabilization. Australis-OSCAR 5 (AO-5). No solar or transponder. Built in Australia. First NASA-launched OSCAR. Phase II Satellites - Developmental, Low Orbit, Operational, Longer Life Span OSCAR 6 15 Oct. 1972 Telemetry, command, Twenty- four telemetry channels. transponder. Two-way communications. Solar. Falsing and beacon problems. Store-and-forward system. Life span exceeded 4 years. Educational materials printed. OSCAR 7 15 Nov. 1974 Two transponders, linear Many countries contributed frequency translation. various technologies and parts. Telemetry, radio teletype. AMSAT-OSCAR 7 (AO-7). Beacons. Relayed with OSCAR 6! Up to 4500 miles low altitude. Almost 7-year lifespan. OSCAR 8 5 Mar. 1978 10-m antenna. Two tran- ARRL operated. Cooperatively sponders (Modes A & J) that built by Project OSCAR, AMSAT could operate simultaneously. and JAMSAT. Lasted 5 years. Phase III Satellites - Operational, High Elliptical Orbit, Longer Life Span (see AMSAT) 712 © 2003 by CRC Press LLC devices and reduced memory requirements. It was succeeded by OS/2 Warp Connect which offered networking through full TCP/IP capabilities. OS/2 Warp version 4 was aimed at corporate users. This version included increased networking features, speech-to-text speech recognition software, and built- in support for Sun Microsystems' Java. See Interna- tional Business Machines, Java, OS/2. OS/2 Warp ServerffiM's Warp Connect system in- tegrated with their local area network (LAN) server 4.0. This version of OS/2 was designed for handling file and device service sharing on networks. See OS/2. OSCAR Orbiting Satellite Carrying Amateur Radio. A series of orbiting satellites originally developed in the homes and garages ofa group of amateur radio enthusiasts. In 1962, the OSCAR Association was incorporated as Project OSCAR, Inc. The early OS- CAR satellite projects began in 1961 and continue today in expanded and more sophisticated forms. Early OSCARs used fairly simple beacon transmit- ters with nonrechargeable batteries, so they were only useful for a few weeks, but they showed what might be accomplished with relatively simple materials and a lot of cooperative effort. Solar cells and telemetry equipment were added to later versions in order to extend useful life and provide greater control over po- sitioning. Relays were then added, with the aim of eventually providing two-way (bidirectional) com- munications. OSCAR-AMSAT projects became increasingly so- phisticated and, by the time the OSCAR 6, 7, and 8 were in orbit, telemedicine and search and rescue sat- ellite communications were demonstrated to be fea- sible. Pioneer OSCAR Satellite The early OSCAR satellites were put together in a cooperative effort out of makeshift donatedparts. yet were well-conceived. pioneer satellite technologies, increasing in sophistication with later projects. OS- CAR III is shown here. The deployment mechanisms of the early OSCARs were particularly interesting to scientists researching satellite installation. The building, launching, and especially the tenuous securement of domestic and international regulatory permissions to launch and op- erate were a great achievement for amateur enthusi- asts, and benefits are still accruing from the hard work and voluntary contributions of radio amateurs. See Overview of OSCAR Projects chart. See AMSAT. oseE Organization for Security and Co-operation in Europe. oscillation 1. Variation, fluctuation, continuing pe- riodic reversal. Although oscillation in the general sense does not imply a regular oscillation, many waves, materials, and circuits studied or constructed by scientists exhibit fairly regular, predictable oscil- lating properties. See quartz. 2. The cyclic alterna- tion ofelectrical properties in a circuit. oscillatorAn electronic device designed to generate a low-current alternating current (AC) power at a particular frequency according to the values of cer- tain constants in its circuits. In microcomputers, an oscillator can be used to provide a reference fre- quency for clocking. An oscillator is also useful for generating test signals. See oscilloscope, quartz. oscilloscope A device designed to provide a visual representation of variations in electrical quantities as a function of time, displayed in the form of pulses or waves on a monitor. The size and form of the waves are traditionally tuned for optimum viewing with knobs, as on an old radio. Oscilloscopes are some- times interfaced with computers to provide a means ofdirectly adjusting and analyzing the oscilloscope signals through software. Oscilloscopes are useful for ~~W~:~ ~~~~e~~~~ee~e~::~t~~~r(:~~. the Open ":. Group). OSI See Open Systems Interconnection. OSI Transport Protocol OSI TP. The ISO-recom- mended communications protocol used by X/Open. OSN 1. operations system network. 2. See Open Sys- tems Networking Initiative. OSP See Operator SelVice Provider. OSPF See Open Shortest Path First Protocol. OSSP See Object Serialization Stream Protocol. OST Office of Science and Technology. AU.K. gov- ernment group founded in 1992 to coordinate science and technology issues across government depart- ments. OSTA See Optical Storage Technology Association. OSTP See Office of Science and Technology Policy. OT See Office of Telecommunications. OTA Office of Technology Assessment (U.S.). OTDR 1. See Office of the Director of Telecommu- nications Regulation. 2. See optical time domain re- flectometer. OTE The primary telecommunications carrier in Greece. aTE is government-owned. OTGR Operations Technology Generic Require- ments. OTH over the horizon. OTN See optical transport network. OTOHAn abbreviation for "on the other hand" com- monly used in email and online public forums. See AFAIK,IMHO. OTP 1. See Office of Telecommunications Policy. 2. See Open Trading Protocol. OTU See optical transport unit. 713 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary OUI See Organizationally Unique Identifier. out-bandlout-of-band signaling Control signaling that is carried separate from the informational por- tion ofa message. See Signaling System 7. out-of-range alert In wireless communications, a beep or light that alerts the user that the handset is at the edge of its range and the user shouldn't move fur- ther from the source of the transmission. outage Loss of power, service interruption. See blackout, brownout. outlet 1. Exit, opening for egress, vent. 2. Plug re- ceptacle in a circuit, usually for electricity or con- nectivity to data transmissions. 3. Source of goods, supplier. outline font, algorithmic font, vector font A char- acter set defined by mathematical algorithms that describe the shape of the letters with graphics primi- tives such as lines, arcs, ellipses, spline curves, etc. That way, when printed or displayed on a monitor, they will be drawn at the best possible resolution of- fered by the display system. Unlike bitmap fonts, which are hand drawn as raster images that cannot be significantly reduced or enlarged, vector fonts look good at sizes ranging from 4 points to 100 points and much larger. Outline fonts are resolution- and plat- form-independent, provided an interpreter is avail- able on the system for the particular format that is being used. Since outline fonts are widely supported on many platforms, this is usually not a limitation. output 1. That which results from, or comes out of, a process or system. 2. The combined signal and con- tent information ofa transmission. 3. The result ofa computer process, e.g., the output ofa word process- ing session might be a printed document, Web page, or a facsimile transmission. output device A device that facilitates the commu- nication or transmission of information, usually in another form or format. In most cases, an output de- vice is a human interface in the sense that it facili- tates the translation or movement of information be- tween nonhuman-readable forms and human-read- able forms, or between single-copy modes and mul- tiple-distribution modes intended for a wider audience. outside plant OSP. The various outside structures, devices, and cabling installations that together com- prise a network. These may be installed above or be- low ground. Those supported by utility poles may be termed aerial. See joint pole for utility pole informa- tion and diagrams. outside plant access cabinet OPAC. Solid, compact weather-resistant cabinets for housing remote-access network equipment and connections, usually in of- fice and industrial park environments. The cabinets may be controlled for factors such as temperature and humidity in order to protect sensitive electronic com- ponents and are usually designed to deter vandalism. Besides leaving more space free inside the building, the outside access cabinet makes it possible for main- tenance personnel to access the devices without en- tering the building premises. outsourcing The process of assigning production or management tasks to an external consultant or organi- 714 zation. Outsourcing is practical when special expertise is needed, or the project is short and hiring new permanent staff would be impractical. Special- ized design projects, advertising, documentation, and cyclic/seasonal projects are often outsourced. Net- work administration is often outsourced by small companies, whereas a company with alarger or more complex network would probably have an in-house system administrator. Telephone answering services are a common form of outsourcing used by small businesses and home busi- nesses. Utilizing an answering service is less expen- sive than hiring a receptionist - a good solution for small companies that don't receive a lot of incoming calls. OutWATS Outward Wide Area Telephone Services. A WATS service for outgoing calls, which is avail- able at bulk-use discounts. See InWATS, WATS. OV2-5 Aresearch satellite designed to measure so- lar and cosmic rays and magnetic influences. It was launched in September 1968 into a circular equato- rial orbit at an altitude of 22,000 miles. A model of the OV2 was donated to the U.S. Air Force Museum by the Northrop Corporation. overcoat-incident recording OCIR. A new technol- ogy for recording optical storage media that permits higher density data per unit area than previous meth- ods such as substrated-incident recording. Tradition- ally, optical discs have used a substrate laid down over the recording surface to protect the data from abra- sions, contamination, and oxidation. This limited the areal density of the recorded information. OCIR technology was developed by Maxoptix (trade- marked as OverCoat Incident Recording with patents pending). In OCIR, the recorded information is im- printed on top of the substrate (similar to hard disk media) and then covered with a protective layer of acrylic that is much thicker than hard disk and tape recording media, but thinner than standard optical recording substrates. Thus, the lens can be positioned closer to the recording surface, realizing ahigher nu- merical aperture (NA) for recording at higher data densities. Maxoptix's goal was to realize 40.GBytes of recorded data at 30 Mbps transfer rates. See air- incident recording, substrate-incident recording, sur- face-array recording. overflow 1. Traffic or data in excess of what is typi- cally found on a system, or in excess of what the sys- tem is capable of handling. Some systems have ad- ditional or alternate circuits, lines, systems, or opera- tors to handle overflow, while others may be slowed down in terms of speed of service, or may cease to function. 2. In telephone circuits, overflow traffic may be diverted to another trunk line. See erlang. overflow, data In programming, an overflow occurs when an operation generates a result for which there is insufficient address or storage space. overhead The portion of a task, data block, or op- eration that provides management informafion per- taining to the task, data, or operation, which is not part of its integral content. For example, the overhead in a graphics file may consist of a header containing © 2003 by CRC Press LLC size and palette information, which is not part of the image itself. The overhead in a parallel processing operation may be the time and processing it takes to handle the logistics of farming out the tasks and re- combining the results of the processes. In networks, overhead exists in the form ofprotocol information, timing infonnation, error data, security bits, routing, priority, and more. Given the amount of overhead in networks, it's a maIVel that they can work so effectively. overhead transparency, foil Atransparent medium receptive to photocopy toner or various inks which is used in conjunction with abright light and projec- tor to project information on a large surface such as a screen or plain wall. Overhead transparencies are often used for presen- tations, especially to illustrate lectures. Overhead transparency films come in a variety of compositions; some can be photocopied in black and white, some in color. Don't use regular transparency paper in a laser printer or photocopier, as the plastic may melt and destroy the internal mechanisms. Cardboard frames can be purchased to support the transparen- cies, which are somewhat flimsy and otherwise hard to hold and organize. overlay 1. n. A keyboard template or sheath. See key- board overlay. 2. n. A template, grid, pattern, image, or other reference information superimposed over a field of view. Overlays are used to measure, count, estimate, asses, evaluate, and embellish the informa- tion or environment over which they are used. See optical combiner, projected; graticule; reticule. 3. v. In programming, a technique in which a limited amount of storage is extended by reusing portions which are not immediately or subsequently required, or by initiating less commonly used routines only on demand. In telephone applications, overlays may be used to bring various tasks into memory as needed. Some versions of BASIC have commands (e.g., LSET) which allow a variable in RAM to be over- written with a subsequent variable in order to prevent eventual slowdowns from garbage collection, that is, from the reorganization of storage to accommodate more information. overlay area code A telephone area code assigned as a parallel code in an existing service area. These are commonly assigned to mobile services, like cel- lular and pager services, so that the area code is sepa- rate from the geographic code assigned to that region. These are not yet prevalent, but are expected to in- crease as mobile services are more widely distributed. See North American area codes for a chart of tele- phone and mobile service area codes. overlay networkAprotocol or application-specific subnetwork, managed and configured independently of its underlying infrastructure, and interconnected by Internet Protocol (IP) encapsulation tunnels over production networks. Recent protocols are supported on overlay networks, including Mbone (multicast IP) and 6bone (IPv6). overlay, video In video editing, it is common to over- lay two video signals, or to overlay a computer sig- nal over a video signal, or vice versa. Newscasts will often overlay a human weather forecaster over a com- puter-generated weather map. In cinema action shots, a stunt worker in a barrel may be overlaid on an im- age of the Niagara Falls. See chromakey. override 1. To overlap, neutralize, take over, domi- nate. Astronger signal, such as an emergency signal, can override aregular transmission. A boss can over- ride the decision of a subordinate; a priority trans- mission can override current transmissions. An op- erator can override a current phone conversation. Some private branch phone systems are configured so that someone in authority has the option of over- riding other conversations, a power that should be used with discretion. overrun To overwhelm, to swarm, to go above or beyond an edge or capacity, to overflow. A cost over- run happens when someone goes over budget or some other allotted quantity. A data overrun can happen when the receiving system isn't fast enough or smart enough to handle the incoming transmission. A printer overrun can happen if the print mechanism continues to function after the paper runs out (some facsimile machines still do this). Overruns often re- sult in discard or loss of information. See cell rate, leaky bucket. oversamplingA process of redundant sampling used in some multiplexing schemes. overscan,full scanAn image output to a monitor that extends to the maximum outer extents of the cath- ode ray tube (CRT) or other scanning display device. Overscan on computers may be achieved by increas- ing the resolution of the display or by adjusting po- sition and size controls associated with the display device. Overscan display modes are common in video applications, where the signal is not being optimized for the computer monitor, but for the video record- ing medium to which it is being output. Overscan may also be a screen option on some systems that are adapted for desktop video and usually adds about 10 to 30 pixels to each edge of the displayable resolu- tion. (Thus, a 320 x 480-scanline interlaced image might become 360 x 525 scanlines in overscan mode, for example.) Flat screen monitors are becoming more widely avail- able, but in the past, cathode ray tubes had asignifi- cant curvature at the outer edges which would dis- tort the image (like looking through a lens) at the outer edges. In order to minimize distortion, the im- age is usually not displayed to its fullest extent, but rather to the point on the front of the tube at which the curve begins. The edge of the monitor casing is usually designed by the manufacturer to fall approxi- mately at the same point or slightly outside the point at which the overscan image falls. See cathode ray tube. overshoot In general terms, atransmitted signal that travels to some point beyond the receiver (too far, too high, at too high a frequency, etc.) or a receiving sys- tem that over-responds to a stimulus signal. Over- shoot may be a compensatory strategy, an undesir- able condition, or a manageable condition (e.g., it may be damped or otherwise moderated). The 715 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary converse is undershoot. Fiber optic sensor probes can help prevent undesired temperature or humidity overshoot in fabrication or controlled environment processes. At the same time, while fiber optic probes may be useful in preventing overshoot in fabrication processes they may, them- selves, be subject to overshoot if they are held too near the object probed such that a resonant frequency amplifies the probe signal and gives an incorrect reading. In electronic logical circuits, a derivative function may be used to assess the rate of change in a system to send an alarm or automatically adjust a component to halt, minimize, or reduce overshoot. In more specific terms in optical communications, overshoot is an undesirable excess occurring as the result of a transition of a signal from one phase or signal level or type to one that is lower. Thus, exces- sive amplitude in a waveform beyond what is desired in a nonsinusoidal wave results in overshoot in fiber optic links. See hysteresis, optical eye pattern mea- surement procedure. overtime period In a pay-per-time-connected ser- vice, the time that elapses after the paid-up period has been exceeded. When using a payphone, the time af- ter the initial insertion of coins has run out is over- time, and the operator may request additional funds or terminate the call. The same general idea applies to per-pay network access, time-sharing, or any other system in which a set amount of time is billed periodically, or is pre- paid, with the option for the user to exceed the usage period as long as additional fees are paid, often at a higher rate. 716 overtone In wave phenomena that can be character- ized as sinusoidal, an integral multiple of the wave frequency, a resonant harmonic, a combination vibra- tion. Overtones may be numbered; the first overtone is twice the frequency of the fundamental reference frequency. Musicians are familiar with audible overtones. For example, on a violin, high-pitched overtones may be generated by bowing a string at a certain resonant vi- brating frequency such that the overtones can just be heard over the main note. Light-based phenomena also exhibit overtones. In spectroscopy, absorption frequencies may exhibit multiple harmonic overtone bands. As these bands become more removed from the fundamental refer- ence frequency, they progressively become more widely separated and lower in intensity. In near-in- frared spectroscopy, the strongest absorption bands usually occur in the first and second overtones. OVS See Open Video System. OWT Operator Work Time. axe See optical cross connect. oxidation The process of combining with oxygen, often resulting in a significant change in the material oxidized that may degrade or otherwise influence its integrity or usefulness for aparticular purpose. Oxi- dation is a particular concern in external wiring in- stallations or cables exposed to water or chemicals. See corrosion. oxymoron A combination of contradictory, incon- gruous words. Puns sometimes have oxymoronic im- plications which mayor may not be true. Satirical ex- amples include: common sense, military intelligence, casual dress, friendly frre, and authentic reproduction. © 2003 by CRC Press LLC P 1. symb. pico 2. abbrev. power. P 1. symb. penneance. 2. symb. peta 3. abbrev. phos- phorus. p connectorApower connector commonly used for attaching internal computer peripherals such as floppy drives, hard drives, CD-ROM drives, etc. Computer power connectors are largely standardized as 4-pin, keyed connectors. (In the late 1970s and early 1980s, they weren't always keyed.) It is preferable to call this apower connector to prevent ambiguity with 68-pin P connectors. See Pconnector. Standardized Peripheral Power Connector A typicalpowerconnectorfor computerperipherals such as hard diskdrives standardized as (A) +12 volts - yellow, (B & C) ground - black, (D) +5 volts - red. Unlike earlier connectors, they are now typically keyed (notched on one side) to prevent incorrect connections. P connector 1. An ANSI-standardized 68-pin elec- trical data connector commonly used for 8-and 16- bit data buses for computer peripherals such as SCSI drives, especially SCSI-3, as a P connector can sup- port wide bus, high-density data transmissions. The Very High Density Cable Interconnect (VHDCI) con- nector is an Alternative 4 P connector with the same pinouts as the 68-pin connector, but it enables mul- tiple SCSI connectors to be connected to one backplate. See A connector. 2. See Polaroid connector. p region In semiconductor component theory and engineering, a region in which the conduction-elec- tron density characteristics result in positive "holes" that can be exploited for their dynamic interactive characteristics. The p region is related to n materials in the n region, where conduction-electron density exceeds hole density. See n region, p-n junction. PSeries Recommendations Aseries of ITV- T rec- ommended guidelines for telephone transmissions quality, installations, and local phone line networks. They are available for download from the ITV-T. Since lTV -Tspecifications and recommendations are widely followed by vendors in the telecommunica- tions industry, those wanting to maximize interoper- ability with other systems should be aware of the in- fonnation disseminated by the ITV- T. A full list of general categories is in the Appendix and specific se- ries topics are listed under individual entries in this dictionary, e.g., M Series Recommendations. See P Series Recommendations chart. P-47 A commercial cesium-doped yttrium silicate (Y SiO s ) powder with a fine grain for fabricating scin- tilrating discs with fast delay times. In conjunction with an appropriate suspension liquid and binder, the powder can be used to coat a glass substrate with a unifonn layerwhich is then baked for about 12 hours to produce a scintillating layer that can be combined with a variety of imaging components. See scintillator. P-frame predictive-coded frame. In MPEG anima- tions, a picture which has been encoded into a video frame according to information extrapolated from past frames in the sequence, using predicted motion compensation algorithms. See B-frame, I-frame, MPEG decoder. P-picture predictive-codedpicture. In MPEG anima- tions, apicture that is to be encoded according to past frames in the sequence using predicted motion com- pensation algorithms. Once it is encoded, it is con- sidered to be a P-frame. See MPEG decoder. P-T pressure-temperature. PIB peak to background (ratio). P3P See Platfonn for Privacy. pA abbrev. picoampere. Pa 1. abbrev. pascal. 2. abbrev. protactinium. PA 1. preliminary assessment. 2. See public address system. PABX See Private Automatic Branch Exchange. PACA 1. See Pacific and Asian Communication As- sociation. 2. Picture Agency Council of America. A trade organization supporting stock image agencies in North America. http://www.stockindustry.org. 3. See Priority Access and Channel Assignment. 717 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary ITU-T P Series Recommendations Telephone transmission quality, telephone installations, local line networks P.I0 Vocabulary of terms on telephone transmission. quality and telephone sets P.ll Effect of transmission impairments P.16 Subjective· effects of direct crosstalk; thresholds of audibility and intelligibility P.30 Transmission perfonnance of group audio· tenninals (GATs) P.32 Evaluation of the efficiency of telephone booths and acoustic hoods P.33 Subscribertelephonesets containing either loudspeaking.receivers or microphones associated with amplifiers P.35 Handset telephones P.36 Efficiency of devices for.preventing the occurrence of excessive acoustic pressure by telephone receivers P.38 Transmission characteristics of operator telephone systems (OTS) P.48 Specificationfor an intermediate reference. system P.SO Test signals P.51 Artificial mouth P.S2 Volume meters P.S3 Psophometer for use on telephone-type circuits P.54 Soundlevel meters (apparatus for the objective measurement of room noise) P.SS Apparatu$ for the measurem~nt of impulsive noise P.S6 Objective measurement of active speech level P.S7 Artificial ears P.S8 Head and torso simulator for telephonometry P.S9 . Artificial conversational speech P 61 Methods for . the calibration of condenser microphones P 62 Measurements on subscribers' telephone equipment P 63 Methods for the evaluation of transmission quality on the basis of objective measurements P.64 Determination of sensitivity/frequency characteristics of local telephone systems P.65 Objective instrumentation for the determinatioD.ofloudness ratings P.66 Methodsfor evaluating the transmission perfonnanceofdigitaltelephone sets P.75 Standard conditioning method for handsets withcarbon.microphones 718 P.76 P.78 P.79 P.82 P.84 P.85 P.310 P.311 P.313 P.340 P.341 P.342 P.3S0 P.360 P.370 P.SOI P.502 P.S61 P.S62 P.581 P.800 P.810 P.830 P.831 Determination of loudness ratings; fundamental. principles Subjective testing method for determination of loudness ratings in . accordance with Recommendation P.76 Calculation of loudness ratings for telephone sets Method for evaluation of service from the standpoint of speech transmission quality Subjective listening test method for evaluating digital circuit multiplication and packetized voice systems A method for subjective performance assessment of the quality of speech voice output devices Transmission characteristics for telephone-band (300 to 3400Hz) digital telephones Transmission characteristics for wideband (1 SO to 7000 Hz) digital handset telephones Transmission characteristics for cordless .and mobile digital terminals Transmission characteristics of hands- free telephones Transmission•characteristics for wideband (150 to 7000 Hz) digital hands-free telephony terminals Transmission characteristics for telephone band (300 to 3400 Hz) digital loudspeaking and hands-free telephony terminals Hands~t dimensions - formerly.ITIJ-T P.35 , Efficiency of devices for preventing the occurrence of excessive acoustic pressure by telephone receivers Coupling.hearing aids to telephone sets Test signals for use in telephonometry Objective test methods for speech communication systems using complex test signals In-service nonintrusive measurement device - voice service measurements Analysis and interpretation of INMD voice service measurements Use of bead and torso simulator (HATS) for hands-free terminal testing Methods for subjective determination of transmission quality Modulated noise reference unit (MNRU) Subjective performance assessment of telephone-band and wideband digital codecs Subjective performance evaluation of network echo cancellers © 2003 by CRC Press LLC Supplements Telephone transmission quality, telephone installations, local line networks, cant. P.Supl Preciu.ltions to be.taken forcorreet instanation and maintenance of an IRS pJst!Pio Y~11sideratiol1st~l~tirlg.to • ttattstnissioncltaraeteristics for analogue handsettelephones P.Stlp14 Subjective performance assessment of digital processes using the modulated noise reference unit (MNRU) P.Sup 15 Wideband (7kHz) moduJatednoise reference unit (MNRU) with noise shaping P.Sup16 Oui~Hnes forplacement of microphones. and loudspeakers in telephone conference rooms and for Gr~l.lpAudioTen:ninals (G~Ts) P.Sttp.l •• 7 Direct.· .• l()u~.es~.· •• ~latt.c~ •••• agaill~ •• ·.tbe interr.nediate referertcesystem (IRS) for the subjective detenninationof loudness ratings P.Sup19 Information on some loudness loss related ratings P.Sup20 Examples of measurements of handset receive-frequency responses: dependence on earcap leakageJosses P.Sup22 Transmission characteristics •. of wideband audio telephones P.Sup23 ITU-T coded-speech database Pacific and Asian Communication Association PACA. A nonprofit educational, literary, and scien- tific organization founded in March 1995. PACAsup- ports and promotes the research, criticism, and ap- plication of artistic, humanistic, and social scientific principles of communication. PAC A publishes the journal Human Communication, and sponsors vari- ous educational workshops and conferences. http://www.ukans.edu/-paca/ pack To compact characters or data together to con- serve space, usually by removing spaces and any other unneeded characters. In the old 4-kilobyte comput- ers from the 1970s that used BASIC as a program- ming language, "string packing" was a means to save precious memory. Database entries and email messages often have a lot ofempty space in them and so may be packed to re- duce the storage size of files. Packing is a simple fonn ofcompression. See compression. Packard, David (1912-1996) American business- man, philanthropist, and founder, along with William Hewlett, of the Hewlett-Packard computer company, one of the well-respected pioneering companies of the computing industry. The company had its humble be- ginnings in the Packard garage in Palo Alto, Califor- nia, and has grown into amultinational company with over 100,000 employees. Packard also cofounded the American Electronics Association, and was a mem- ber of the President's Council of Advisors on Science and Technology for 4 years. Hewlett, William R.; Hewlett-Packard. PackedEncodingRules PER. Developed in the early 1990s, PER is one of three major encoding schemes used in open architectures development. Unlike BER, tags are ignored and length fields may be omitted. PER provides a means for creating more succinct encodings optimized for bits on the line and gener- ally has lower bandwidth requirements than BER or LWER. See Basic Encoding Rules, LightWeight En- coding Rules. packet 1. A generic tenn for a unit of data fonned as a bundle with acertain specified organization, accord- ing to a protocol. Other designations for network units and bundles include cell and frame. Although packet fonnats vary, they most typically include a header, an infonnation payload, and a trailer. The header may contain anumber of pieces of infonnation, including priority, source, destination, length of packet, etc. The payload is the message or infonnation being sent, and may be split over a number of packets. The trailer may include flags, signals, and error detection or correc- tion data. When a series ofrelated packets is trans- mi tted over anetwork, they may not all take the same route, and so disassembly, routing, and assembly pro- cedures may be applied to transmitted packets; in- structions to coordinate this process mayor may not be included in some of the packets. Sometimes packet-switched networks are connected to non-packet-switched networks, in which case tunneling takes place, or conversion through a packet assembler/disassembler, to accommodate the differences in formats. Subjective perfonnance evaluation of hands-free terminals Methodology forderivation~f equiPl\1entim~~ent f~cto~I:r0tt1 subjective·· •• liste~ing-onlY.test~.:.; ••• : ••• : Objective quality·measuremetttof telephone-band (300 to 3400Hz) speech codecs PercetJtual evaluation of speech quality- (PESQ), an objective method for end-to-end speech quality assessment of narrowband telephone net\Vorks and speech cadecs Subjective videoqualityasse~~ent methods for multimedia applications Subjective audiovisual quality assessment methods for multimedia ap~li~~~ns.\/ .•. Interactive testmethOds for audiovisual. communications Principles of a reference impainnent syste1T1for video: . . Multimedia C011lD1wUriations delay, synchronization and frame rate measurement P.833 P.910 P.861 P.832 P.862 P.93 0 P.931 P.920 B911 719 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary packet assembler/disassembler PAD. In packet- based systems, information is converted into data units known as packets, and then transmitted. At the receiving end, these packets are apprehended and dis- assembled to tum them back into the information con- tained in the original content. packet fIltering The evaluation ofpacket structure or contents in order to selectively reject or accept pas- sage of the packet through a network junction. See fIrewall. packet radio Packet radio is a combination of com- puter equipment and radio transmissions used to ex- change messages. Microcomputers and terminal node controllers (TNCs) are commonly used in packet ra- dio systems. The computer is cabled to a radio trans- ceiver at each end of the communication. Because computers have store and forward, or other types of scheduling capabilities, the operator doesn't have to be present when the message is sent or received. In radio, this is called time-shifted communications. The system could be configured to send at a time when interference is less likely to be encountered, or when a favorable time of day occurs at the sending or re- ceiving end. Packet radio transmission speeds are fast enough that various types of propagation can be used, including meteor-scatter. Due to the nature ofpacket transmis- sion and its built-in error-correcting mechanisms, packet transmissions are reliable. Packet radio uses a number ofprotocols and favors the Open Systems Interconnection (OSI) reference model. Common protocols in use include NETIROM, AX.25, TCP/IP, and ROSE. packet reservation multiple access PRMA. An en- hanced time division multiple access (TDMA), which incorporates aspects of S-ALOHA. It is suitable for mobile transmissions. See ALOHA, time division multiple access. packetsnifferA diagnostic and snooping mechanism for examining the contents of network packets dur- ing transmission. See packet tracing. packet switched radio See packet radio. packet switching Acomputer communications tech- nology developed in the early 1960s that bundles up information into discrete data packets which can, be sent out in separate paths, like breaking up the cars on a train sending them on separate tracks, and put- ting them all back together again at the destination. In the 1960s, computing was becoming more acces- sible, generating greater interest in its use and spurring the manufacture ofvarious types of systems. Practi- cal packet-switched implementations began to appear in the 1970s, and separate server computers to handle various specialized purposes, such as accounting, opened the doors to the development of various types ofdistributed computing architectures. The rise of ARPANET greatly influenced the devel- opment and acceptance of packet switching. With hosts springing up in distant locations and special- ization and the variety of computing tasks increas- ing, packet switching was a practical way to facili- tate intercomputer communications. 720 Gradually, layered architectures emerged, separating user functions and applications from lower level op- erating functions. This enabled information carried in packets to be communicated through many differ- ent types of systems, while still retaining the unique operating features and user interfaces of each system. Historically, telephone networks were built around circuit-switching. This meant that a dedicated path through the switching system had to be established (and was tied up) for the duration of the call. In a large global network where many institutions are online all the time, this is not apractical solution. Abetter way for large systems is to route information through whatever path is most practical at the time (since some systems may be inaccessible or offline without no- tice), to divide the packets up, if necessary, if routes change while the data are en route, and to resend any portions of the message that don't make it through. It works 24 hours a day, and will continue to try to send the data in adynamically changing environment, even if intermediate hosts or the receiving party are tem- porarily offline. This essential flexibility is at the heart ofpacket-switching architectures and is incorporated into huge cooperative systems like the Internet. See circuit switching, Open Systems Interconnection, Systems Network Architecture, X.25. packet switching network A communications net- work in which achannel is occupied only for the time during which the packet, a unit of data, is transmit- ted, a common distributed data network format. See Frame Relay. packet tracing See packet sniffer. pad connector Short for touchpad connector. Acon- nector that enables atouchpad keyboard (with a flat surface rather than raised keys) or other flat input configuration to be attached to an electronic device (usually a computer or kiosk terminal). PAG See Producers Advocacy Group. page description language POL. A means ofprovid- ing commands to a system for the placement and for- matting of page elements, such as text and graphics. Adobe PostScript is widely used, powerful page de- scription language, and HTML is a very basic page description language extensively used to format in- formation for viewing with a Web browser. Various printers include page description languages which are usually somewhere between PostScript and HTML in complexity. pager 1. A general broadcasting loudspeaker con- nected to a phone or microphone, usually in a busi- ness, or educational or health care institution. See public address system. 2. Aportable, wireless hand- held device which can emit an audible, short verbal message or short alphanumeric message. These are often used by emergency workers, sales representa- tives, and business professionals. See paging. pagingAlerting arecipient that there is a message or item awaiting his or her attention. Public address sys- tems can be used to page employees or clientele when packages are ready, when there is a phone call, or when lost children or items have been located or turned in. Pagers commonly known as beepers are © 2003 by CRC Press LLC portable wireless devices that will make an audible beeping sound to signal that a message or call is wait- ing, or that the user has to go to a certain location if paged. Portable wireless alphanumeric pagers can dis- playa short message or telephone number to notify the user ofa situation or phone message. Pagers are commonly used by professionals in the field, emer- gency workers, and industrial yard workers. See pub- lic address system, Short Message Service. pagingsystem PSI A system which allows a message to be broadcast broadly to anyone wi thin range of the speaker, usually to attract the attention ofa particu- lar person or party, to give instructions, or to ask someone to pick up a message. Paging systems are common in hospitals, schools, and shopping malls. See public address system. pair A pair of associated wires, often twisted together to facilitate electrical conductance and/or to reduce noise. Most phone networks are based upon decades- old circuits of twisted-pair copper wires. A pair of cables is used in a number of multimedia schemes, wi th one carrying sound and the other graphics, or one carrying sound and graphics data while the other carries timing information. pair assignment The assigning ofa specific current, transmission, or function to a twisted-pair wire. These are often designated with a code or color, in order to make interconnections quicker and less error-prone. PAL 1. See phase alternate line. 2. See programmable array logic. PALC plasma-addressed liquid crystal. See liquid crystal display, plasma display panel. Paley, William S. An American experimenter and business tycoon who purchased and developed the Columbia Phonograph Broadcasting System (1927) into the Columbia Broadcasting System (CBS) in 1928. Under his leadership, the company grew and added new products and services to its line. In 1983 Paley retired from CBS, only to return 3 years later to work with Lawrence Tisch. In 1995 CBS was bought by Westinghouse. In 1975, Paley established the Museum of Television and Radio in New York, an educational resource and archive of historical and culturally important broad- casts. The William S. Paley Foundation, Inc. has been established in his honor. Palo Alto Research Center PARCo One of several Xerox research installations, PARC was founded in 1970 in the Stanford University Industrial Park. It is the site of many remarkable pioneer developments in the field of computers and telecommunications. The PARC was a hotbed in the 1970s for many original developments in object-oriented programming and computer interface design. Both Apple and Microsoft toured the facility in their early days and were inspired by their experiences there, particularly demon- strations of the Alto computer running Smalltalk applications. See Kay, Alan; Smalltalk. PAM 1. payload assist module. Ashuttle satellite de- ployment mechanism. The satellite in this context is considered the payload. 2. See port adapter module. 3. See pulse amplitude modulation. panel switch A commercially successful electrome- chanical telephone switching system developed in the AT&T labs in 1921, based on Lorimer one-step se- lection concepts. It incorporated mechanical selectors to connect calls. At the time the panel switch was introduced, inde- pendents were widely using the step-by-step switch developed a year earlier. The panel switch technol- ogy allowed customers to dial their own calls, albeit with a lot of noise in the early versions. The panel switch was widely used in the United States until the 1950s, when it was superseded by the crossbar switch, which had been developed in the late 1930s. See crossbar switch, Lorimer switch, rotary switch, step- by-step switch. panoramic receiverA device used in radio commu- nications which provides continuous monitoring of a specified band of frequencies. On acomputermoni- tor, signals are displayed in graph form, with vertical blips moving horizontally along the X axis and am- plitude graphed on the Y axis. PAP 1. packet-level procedure. 2. See Public Access Profile. paper tape An infonnation storage medium. Paper designed to have specific areas of the tape encoded and punched or electrostatically recorded onto the tape, for subsequent reading by a paper tape reader or other interpretive device, such as a computer, stock ticker machine, player piano, or music box. This means of information encoding and storage was used to program early computers and had many character- istics in common with computer punch cards. Early telegraph receivers used paper tape systems designed by inventors such as Bain and Morse. Later teletypewriter systems used tapes to save transmis- sion time and money by being composed offline and sent only when complete. This also provided a way to correct significant errors before transmission, since a bad tape could always be repunched. Paper tapes have been superseded by tape drives, hard drives, floppy diskettes, magneto-optical discs, cartridges, and memory cards. See Bain, Alexander; Morse, Samuel F. B. paper tape punch A device designed to receive or interpret coded information and translate it into physi- cal locations on a paper tape and punch them accord- ingly. paper tape reader A device which detects and trans- lates the encoded holes in punched paper tape as the tape moves through the machine. The machine may be an interface to a display device, or may be self- contained. Older paper tape readers required that the holes be completely punched out and were usually read by optical means. Later machines could read semi-perforated or chadless tape, usually by means of physical sensors. See Hollerith code, paper tape punch, punch card. PAR 1. Positive Acknowledgment Retransmit. 2. Pre- cision Approach Radar. parabolaA plane curve that is frequently studied and described in various disciplines including physics, geometry, and art. Parabolic curves are observed in 721 © 2003 by CRC Press LLC . Press LLC Fiber Optics Illustrated Dictionary OUI See Organizationally Unique Identifier. out-bandlout-of-band signaling Control signaling that is carried separate from the informational por- tion ofa message. See Signaling System 7. out-of-range. printed document, Web page, or a facsimile transmission. output device A device that facilitates the commu- nication or transmission of information, usually in another form or format. In most cases, an output de- vice is a human interface in the sense that it facili- tates the translation or movement of information be- tween nonhuman-readable forms and human-read- able forms, or between single-copy modes and mul- tiple-distribution modes intended for a wider audience. outside. period In a pay-per-time-connected ser- vice, the time that elapses after the paid-up period has been exceeded. When using a payphone, the time af- ter the initial insertion of coins has run out is over- time, and the operator may request additional funds or terminate the call. The same general idea applies to per-pay network access, time-sharing, or any other system in which a set amount of time is billed periodically, or is pre- paid, with the option for the user to exceed the usage period as long as additional fees are paid, often at a higher rate. 716 overtone In wave phenomena that can be character- ized as sinusoidal, an integral multiple of the wave frequency, a resonant harmonic, a combination vibra- tion. Overtones may be numbered; the first overtone is twice the frequency of the fundamental reference frequency. Musicians are familiar with audible overtones. For example, on a violin, high-pitched overtones may be generated by bowing a string at a certain resonant vi- brating frequency such that the overtones can just be heard over the main note. Light-based phenomena also exhibit overtones. In spectroscopy,