Fiber Optics Illustrated Dictionary - Part 73 docx

output device A device that facilitates the commu-nication or transmission of information, usually in another form or format.. Pconnector1.AnANSI-standardized 68-pin elec-trical data con

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

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)

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)

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

OSCAROrbiting Satellite Carrying Amateur Radio

A series oforbiting satellites originally developed in

the homes and garages of a 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 ofmakeshift donated parts 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-and voluntary contributions of radio amateurs See Overview of OSCAR Projects chart See AMSAT

oseEOrganization for Security and Co-operation

in Europe

oscillation1 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 of electrical properties in a circuit

oscillator Anelectronic 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

oscilloscopeA device designed to provide a visual representation ofvariations in electrical quantities as

a function oftime, displayed in the form ofpulses 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

of directly adjusting and analyzing the oscilloscope signals through software Oscilloscopes are useful for

~~W~:~~~~~e~~~~ee~e~::~t~~~r(:~~. the Open " : Group)

OSISee Open Systems Interconnection

OSI Transport ProtocolOSI TP The ISO-recom-mended communications protocol used by X/Open

OSN1 operations system network 2 See Open Sys-tems Networking Initiative

OSPSee Operator SelVice Provider

OSPFSee Open Shortest Path First Protocol

OSSPSee Object Serialization Stream Protocol

OSTOffice of Science and Technology.A U.K. gov-ernment group founded in 1992 to coordinate science and technology issues across government depart-ments

OSTASee Optical Storage Technology Association

OSTPSee Office of Science and Technology Policy

OTSee Office of Telecommunications

OTAOffice ofTechnology Assessment(U.S.).

OTDR1 See Office of the Director of Telecommu-nications Regulation 2 See optical time domain re-flectometer

OTEThe primary telecommunications carrier in Greece aTE is government-owned

OTGR Operations Technology Generic Require-ments

OTHover the horizon

OTNSee optical transport network

OTOH Anabbreviation 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

OTUSee optical transport unit

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 ofits 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 of a transmission 3 The result of a

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

termedaerial 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

managementtasksto an external consultant or

organi-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 a larger 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 ofincoming 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 A research 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 Anew 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 a higher 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-air-incident recording, sur-face-array recording

overflow 1 Traffic or data in excess ofwhat is

typi-cally found on a system, or in excess ofwhat the sys-tem is capable of handling Some syssys-tems 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 ofits integral content For example, the overhead

in a graphics file may consist of a header containing

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 of protocol information,

timing infonnation, error data, security bits, routing,

priority, and more Given the amount of overhead in

networks, it's amaIVel that they can work so effectively

overhead transparency, foilA transparent medium

receptive to photocopy toner or various inks which

is used in conjunction with a bright 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 ofcompositions;

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

overlay1.n.Akeyboard 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 fromgarbage collection, that is,

from the reorganization of storage to accommodate

more information

overlay area codeA 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 networkA protocol 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, videoIn video editing, it is common to

over-laytwo video signals, or to overlay a computer

sig-nal over a video sigsig-nal, or vice versa Newscasts will

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

override1 To overlap, neutralize, take over, domi-nate Astronger signal, such as an emergency signal, can override a regular transmission Aboss can over-ride the decision of a subordinate; a priority trans-mission can override current transtrans-missions.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

overrunTo overwhelm, to swarm, to go above or beyond an edge or capacity, to overflow Acost 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

oversamplingAprocess ofredundant sampling used

in some multiplexing schemes

overscan, full scan Animage 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 adjustincreas-ing 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 berecord-ing 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 a signifi-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

overshootIn general terms, a transmitted 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 manageundesir-able condition (e.g., it may be damped or otherwise moderated) The

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

Inelectronic 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

Inmore 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

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

OVSSee Open Video System

OWT Operator Work Time

axeSee 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 a particular 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

P 1.symb.penneance 2.symb.peta- 3.abbrev.

phos-phorus

pconnectorA power 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 connectorto prevent ambiguity with 68-pin

P connectors See P connector

Standardized Peripheral Power Connector

A typicalpower connectorfor computerperipherals

such as hard disk drives standardized as (A)+ 12volts

- yellow, (B& C)ground - black, (D)+ 5volts - red.

Unlike earlier connectors, they are now typically keyed

(notched on one side) to prevent incorrect connections.

Pconnector1.AnANSI-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 anAlternative4P 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 regionInsemiconductor 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

P Series RecommendationsA series 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 SincelTV-T specifications 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 entse-ries in this dictionary, e.g., M Series Recommendations See P Series Recommendations chart

P-47 A commercial cesium-doped yttrium silicate (Y SiOs)powder with a fine grain for fabricating scin-tilrating discs with fast delay times.Inconjunction with an appropriate suspension liquid and binder, the powder can be used to coat a glass substrate with a unifonn layer which is then baked for about 12 hours

to produce a scintillating layer that can be combined with a variety ofimaging components See scintillator P-framepredictive-coded frame InMPEG anima-tions, a picture which has been encoded into a video frame according to information extrapolated from

pastframes in the sequence, using predicted motion compensation algorithms See B-frame, I-frame, MPEG decoder

P-picturepredictive-coded picture.InMPEG anima-tions, a picture that is to be encoded according topast

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)

P3PSee Platfonn for Privacy

pAabbrev.picoampere

Pa1.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

Fiber Optics Illustrated Dictionary

ITU-T P Series Recommendations

Telephone transmission quality, telephone

installations, local line networks

P.I0 Vocabulary ofterms on telephone

transmission quality and telephone sets

P.ll Effect of transmission impairments

P.16 Subjective· effects of direct crosstalk;

thresholds ofaudibility 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 Subscribertelephone sets containing

either loudspeaking receivers or

microphones associatedwithamplifiers

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 Specification foranintermediate

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 ofroom noise)

P.SS Apparatu$ for themeasurem~ntof

impulsive noise

P.S6 Objective measurementof 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 Methods for evaluating the transmission

perfonnanceofdigitaltelephone sets

P.75 Standard conditioning method for

handsets withcarbon.microphones

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 loudnessratings;

fundamental principles Subjective testing method for determination ofloudness ratings in accordance with RecommendationP.76 Calculation of loudness ratings for telephone sets

Method for evaluation ofservice 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(1SOto7000Hz) digital handset telephones

Transmission characteristicsfor cordless and mobile digital terminals

Transmission characteristics of hands-free telephones

Transmission•characteristics for wideband (150to7000Hz) digital hands-free telephony terminals Transmission characteristics for telephone band (300 to 3400Hz)digital loudspeaking and hands-free telephony terminals

Hands~tdimensions - formerly.ITIJ-T P.35 ,

Efficiency ofdevices for preventing the occurrence ofexcessive acoustic pressureby 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 ofbead and torso simulator (HATS) for hands-free terminal testing

Methods for subjective determination of transmission quality

Modulated noise referenceunit(MNRU) Subjective performance assessment of telephone-band and wideband digital codecs

Subjective performance evaluation of network echo cancellers

installations, local line networks, cant

P.Supl Preciu.ltions to be.taken forcorreet

instanation and maintenance ofan

IRS

pJst!Pio Y~11sideratiol1st~l~tirlg.to •

ttattstnissioncltaraeteristicsfor

analoguehandsettelephones

P.Stlp14 Subjective performance assessment of

digital processesusingthe modulated

noise reference unit(MNRU)

P.Sup15 Wideband(7kHz)moduJatednoise

reference unit(MNRU) withnoise

shaping

P.Sup16 Oui~Hnesforplacement 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 Informationon someloudness loss

related ratings

P.Sup20 Examples of measurements ofhandset

receive-frequency responses:

dependence on earcap leakageJosses

P.Sup22 Transmission characteristics•.of

wideband audiotelephones

P.Sup23 ITU-T coded-speechdatabase

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 PACA publishes the journalHuman Communication,and sponsors vari-ous educational workshops and conferences http://www.ukans.edu/-paca/

packTo compact characters or data together to con-serve space, usually by removing spaces and any other unneeded characters.Inthe 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

of empty space in them and so may be packed to re-duce the storage size offiles Packing is a simple fonn

of compression See compression

Packard, David(1912-1996) American business-man, philanthropist, and founder, along with William Hewlett, ofthe Hewlett-Packard computer company, one ofthe well-respected pioneering companies ofthe computing industry The company had its humble be-ginnings in the Packard garage in Palo Alto, Califor-nia, and has grown into a multinational company with over 100,000 employees Packard also cofounded the American Electronics Association, and was a mem-ber of the President's Council ofAdvisors on Science and Technology for 4 years Hewlett, William R.; Hewlett-Packard

Packed Encoding RulesPER 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

packet1.Ageneric tenn for a unit of data fonned as

a bundle with a certain specified organization, accord-ing to a protocol Other designations for network units and bundles includecellandframe.Although packet fonnats vary, they most typically include a header,

an infonnation payload, and a trailer The header may contain a number ofpieces of infonnation, including priority, source, destination, length ofpacket, etc The payload is the message or infonnation being sent, and may be split over a number ofpackets The trailer may include flags, signals, and error detection or correc-tion data When a series of related packets is trans-mitted over a network, 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

Methodologyforderivation~f

equiPl\1entim~~ent f~cto~I:r0tt1

subjective··••liste~ing-onlY.test~.:.;•••:•••:

Objective quality· measuremetttof

telephone-band (300to3400Hz)

speech codecs

PercetJtual evaluation of speech

quality- (PESQ), an objective method

for end-to-end speech quality

assessment ofnarrowband telephone

net\Vorksandspeech cadecs

Subjectivevideoqualityasse~~ent

methods for multimediaapplications

Subjectiveaudiovisual 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.930

P.931

P.920

B911

Fiber Optics Illustrated Dictionary

packet assembler/disassemblerPAD 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 totumthem back into the information

con-tained in the original content

packet fIlteringThe evaluation of packet structure

or contents in order to selectively reject or accept

pas-sage of the packet through a network junction See

fIrewall

packet radioPacket 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 rara-dio

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 calledtime-shiftedcommunications 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 of protocols 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

packet snifferAdiagnostic and snooping mechanism

for examining the contents of network packets

dur-ing transmission See packet tracdur-ing

packet switched radioSee packet radio

packet switchingAcomputer communications

tech-nology developed in the early 1960s that bundles up

information into discrete datapacketswhich 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 of various 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 ofvarious types

of distributed computing architectures

The rise ofARPANET 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

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 ofeach 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 ofthe call In a large global network where many institutions are online all the time, this is not a practical solution A better 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 ofthe message that don't make it through It works 24 hours a day, and will continue totryto send the data in a dynamically 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 networkA communications net-work in which a channel 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 tracingSee packet sniffer

pad connectorShort for touchpad connector A con-nector that enablesatouchpad 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)

PAGSee Producers Advocacy Group

page description languagePOL Ameans 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 A portable, 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 a recipient 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 beepersare

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 of a 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

paging systemPSI Asystem which allows a message

to be broadcast broadly to anyone within range ofthe

speaker, usually to attract the attention of a

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

pairApair ofassociated 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,

with one carrying sound and the other graphics, or

one carrying sound and graphics data while the other

carries timing information

pair assignmentThe 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

PAL1 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.In1983

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 ofTelevision

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 CenterPARCo One of several

Xerox research installations, PARC was founded in

1970 in the Stanford University Industrial Park It is

the site ofmany 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

chanical telephone switching system developed in the AT&T labs in 1921, based on Lorimer one-step se-lection concepts.Itincorporated 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 receiver Adevice used in radio commu-nications which provides continuous monitoring of

a specified band offrequencies On a computermoni-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 tapeAn 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 ofinformation 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 punchA 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 readerAdevice 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

parabolaAplane curve that is frequently studied and described in various disciplines including physics, geometry, and art Parabolic curves are observed in