Fiber Optics Illustrated Dictionary - Part 71 pptx

Nyquist theoremThe Nyquist theorem is an impor-tant principle in telecommunications, where audio samples are used for synthesized voice, "music on hold," videoconferencing, Internet phon

Fiber Optics Illustrated Dictionary

made presentations through influential organizations

such as the National Telecommunications

Informa-tion AdministraInforma-tion (NTIA) conference In 1996, Bell

Atlantic announced a merger with NYNEX, a plan

that was carried out in 1997 The announced merger

received Federal Communications Commission

(FCC) approval to become the second-largest single

telephone company, stretching from Maine to

Virginia

Nyquist, Harry(1889-1976) ASwedish-born

physi-cist and engineer, Nyquist emigrated to the U.S in

1907 Nyquist had an early interest in the

transmis-sion of pictures, resulting in the development of a

historic facsimile system, AT&T'stelephotography

machine, in 1924 In the 1920s, Nyquist was also

ac-tive in studying telegraph communications and

pro-viding theoretical observations related to

transmis-sion speeds and signal values In 1928, he described

principles for the digital sampling of analog signals

inCertain Topics in Telegraph Transmission Theory.

Unfortunately, theory came far ahead of practice;

equipment at the time could not practically embody

Nyquist's theories, but they are now the basis for

digi-tal sound sampling TheNyquist theorem is named

for this work; Claude Shannon who, like Nyquist,

worked at the Bell Laboratories, cites Nyquist in his

later development ofinformation theory, in the 1940s

In 1927, Nyquist mathematically described Johnson

noise, which is important in the understanding of

in-terference in electronics In the 1930s, he turned his

interest to the study of amplifiers Throughout his

career he developed both theory and systems and is

credited with more than 100 patents See Nyquist

theorem, sampling

Nyquist frequencySee Nyquist theorem

Nyquist minimumThe minimum bandwidth that can

be used to represent a signal This measure is used to

limit the spectral width of a transmission signal in

order to reduce the chance of interference and to

maximize efficient use of the signal See Nyquist

theorem

Nyquist theoremThe Nyquist theorem is an

impor-tant principle in telecommunications, where audio

samples are used for synthesized voice, "music on

hold," videoconferencing, Internet phone, and other

multimedia and digital voice communications

Au-dio sampling is a process of taking digital slices of

an analog signal in order to store and reconstruct the

signal to preserve the original sound In general, the

slower the sampling rate, the coarser the recreated

sound; the higher the sampling rate, the better the

rec-reated sound There are thresholds, however Above

certain thresholds there may be no perceptual

im-provement and artifacts and other technical

interfer-ence will begin to negatively affect the quality of the

recreated sound Below certain thresholds, the sound

may not contain enough information to be intelligible There are also thresholds in the relationship between the frequencies sampled and the sampling rate The Nyquist theorem is named for Harry Nyquist, who studied and described these important basic prin-ciples as they related to communications in the 1920s The Nyquist theorem describes a sampling quality threshold relationship between the phase of the har-monically related sine and cosine functions over a specified time interval In practical application then,

an analog signal waveform sampling at equal time intervals requires a sampling rate of at least twice the highest frequency component in the analog signal to fully represent the characteristics of the original sound Or stated another way, the highest frequency that can be accurately represented in a sampled sig-nal is equal to one-half of the sampling rate This translates to two samples per cycle and is called the

Nyquist frequency or Nyquist limit Thus, a full

sample of 10kHz of audio bandwidth would have to

be captured at a rate of20 kHz (or higher, within other thresholds) or information would be lost or introduce artifacts.Intheory, the sampling rate can be infinitely high and the samples infinitely narrow.Inpractice, usually sound sampling rates ofabout 8 to 44 kHz are used

Iffrequencies in the sample are higher than the Nyquist rate, an artifact known as aliasing will oc-cur Thus, in theory, if a sound sample possesses fre-quencies up to 10kHz, but the sound is sampled at a rate at 18 kHz, then frequencies over 9 kHz should

be filtered to prevent aliasing Inpractice, signals above the Nyquist frequency may be filtered to re-duce aliasing in the recreated sound sample Theo-retically, the filter would enable us to get back a pretty faithful representation of the original frequencies within the sample that are up to 9 kHz In real life, filters have phase shift and slope characteristics that may interfere with a perfect re-creation

Other limitations in sound sampling and re-creation are the digi tal storage and bus characteristics of the digital sampling system.Inmost systems, you need

at least 8 bits to make decent-sounding voice, and 16 bits for a decent representation of music Higher ca-pacities are needed to accommodate higher dynamic ranges and more sophisticated sounds Sound periph-eral cards for computers and synthesizers with

16-or 32-bit sampling capacities did not become widely available until the late 1990s

The Nyquist theorem has also been applied to video sampling, but it has been found that higher sampling frequencies may be needed for video compared to sound, with suggestions that four times the highest frequency may be necessary for a full re-creation of the original image See Fourier transform; Nyquist, Harry; sampling; Shannon, Claude

vices to indicate "off." On rocker switches, it

indi-cates the side of the rocker which turns an appliance

or component off Its complement is "I" to designate

"on."

oSeries RecommendationsA series oflTU-T

rec-ommended guidelines for specifications of

measur-ing equipment that can be purchased from the lTU-T

Since lTU-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-formation disseminated by the ITV-T A full list of

general categories is listed in Appendix C and

spe-cific series topics are listed under individual entries

in this dictionary, e.g., K Series Recommendations

See 0 Series Recommendations chart

O&M,0 &M operations and maintenance

O-bandA transmission band specified by the lTU

for optical transmissions in the 1260 - 1310-nm

range

OIPoutput

OIROriginator/Recipient A concept associated with

the X.400 Message Handling System (MHS) The

OIRaddress is used by the MTS for routing

OAISee Open Application Interface

OALC4A family of relatively small-diameter fiber

optic submarine cables developed by Alcatel These

cables are specifically intended for repeater-equipped

systems They can house up to 16 optical fibers within

a welded steel tube A gel substance protects the

fi-bers from moisture and hydrogen effects A steel wire

vault surrounded by a seam-welded copper tube

pro-vides additional protection High-density

polyethyl-ene provides abrasion resistance Cables of the

OALC4 family are suitable for use at sea depths of

between 0 and 7000 to 8000 m, depending upon the

ohms per kilometer rating

OAMoperations, administration, and maintenance

Various related management functions often

associ-ated with telephone and computer networks In

tele-phone networks, significant management and

ac-counting tasks are associated with maintaining a

dy-namic environment in which subscribers all request

different types and levels of service, and where the

subscriber population is very mobile, thus changing

have computer networks and entire facilities associ-ated with just these aspects of the business With mobile communications on the rise, these manage-ment tasks become even more intricate, and computer systems are used to facilitate the administrative tasks OAM Operations And Maintenance Preventive maintenance information which, in an ATM B-ISDN environment, is included in the transmitted cells OAM&Poperation, administration, maintenance, and provisioning

OAM&P ANSI standardsThere are a number of important American National Standards (ANSI) of Committee Tl related to OAM&P, which are avail-able from ANSI and described in the fonn ofabstracts

on the Web See the ANSI Standards OAM&P chart for examples

OAOorbiting astronomical observatory Since 1966,

a series of OAOs has been launched from Cape Canaveral to explore and measure astronomical phe-nomena that can more easily be seen from outside the Earth's atmospheric envelope

OASee office automation

OASSee Organization ofAmerican States OBISee Open Buying on the Internet

object1 A thing, article, entity, or unit of informa-tion 2 An individually identifiable part, entity, or component 3 In programming, an entity, often com-partmentalized, that stores or receives data, e.g., a byte, block, register, segment, etc 4 In the X Win-dows System, a software concept practically imple-mented as private data with private and public rou-tines to operate on that data 5 In typed objects, an entity that interacts as part of a defined operation object, programmingInobject-oriented program-ming, a reusable, modular, ''wrapped up" collection ofsoftware characteristics, functions, and parameters

at a basic level For example, a button may be de-signed with certain visual and operational character-istics and stored for reuse in various applications, so that the code for the object isn't constantly reinvented

Anobject may consist ofa collection of other objects

to serve some related or higher function See class Object Database Management GroupODMG An independent standards organization now called the Object Data Management Group to reflect the broader

Fiber Optics Illustrated Dictionary

lTU-T 0 SeriesReeommendatioDs

0.1 Scope and application of measurement

equipment specifications coveredin the

O-series Recommendations

0.3 Climatic conditions and relevant tests for

measuring equipment

0.6 l020-Hz reference test frequency

0.9 Measwingarrangementstoassess the

degree of unbalance·about"Earth

0.11 Maintenance accesslines

0.22 CCITT automatic ·transmission

measuring and signaling testing

equipmentATMENo.2

0.25 Semiautomatic in-circuit echo

suppressor testing system (ESTS)

0:27 In-station echo canceller testequipment

0.31 Automatic measuring equipment for

sound-program circuits

0.32 Automaticmeasuring·equipment for

stereophonic pairs of sound-program

circuits

0.33 Automatic equipment for rapidly

measuring stereophonicpairs and

monophonic sound-program circuits,

links, and connections

0.41 Psophometer for use on telephone-type

circuits

0.42 Equipment to measure nonlinear

distortion using the 4-tone

intermodulation method

0.51 Volume meters

0.61 Simple equipment to measure

interruptions on telephone-type circuits

0.62 Sophisticated equipment to measure

interruptions on telephone-type circuits

0.71 Impulsive noise measuring equipment

for telephone-type.circuits

0.72 Characteristicsofan impulsive noise

measuring·instrument for wideband data

transmissions

0.81 Group-delay.measuring equipment for

telephone-type circuits

0.82 Group-delaymeasuring equipment for

the rangeof5 to600kHz

0.91 Phase jitter measuring equipment for

telephone-type circuits

0.95 Phase and amplitude hit counters for

telephone-type circuits

0.111 Frequency shift measwingequipment

roruse on carrier channels

0.131 Quantizing distortion measuring

equipment using a pseudo-random noise

test signal

0.132 Quantizing distortion measuring equipment usinga·sinusoidal test signal 0.133 Equipment for measuring the

perfonnance ofPCM encoders and decoders

0.150 General requirements for instrumentation for performance measurements on digital transmission equipment

0.151 Error perfonnance measuring equipment operatingat the primary rate and above 0.152· Error perfonnance measuring equipment for bit rates of64Kbps andNx64Kbps 0.153Basic parameters for the measurement of error performance at bit rates below the primary rate

0.161 In-service code violation monitors for digital systems

0.162 Equipmenttoperform in-service monitoring on 2048-, 8448-, 34,368- and 139,264-Kbps signals

0.163 Equipment to perform in-service monitoring on 1544-Kbps signals 0.171 Timing jitter and wander measuring equipment for digital systems based upon the plesiochronous digital hierarchy(FDB)

0.172 Jitterand wander measuring equipment fordigital systems based upon the synchronous digital hierarchy (SDH) 0.181 Equipmenttoassess error performance

onSTM-N interfaces 0.191 Equipment to measure the cell transfer performance ofATM·connections Supplements

O.Sup3.1 Measuring instrument requirements

- sinusoidal signal generators and level-measuring instruments 0.Sup3.2 Noise measuring instruments for

telecommunication circuits 0.Sup3.3 Principal characteristics ofvolume

indicators 0.Sup3.4 Consideration ofinterworking

between different designs of apparatus for measuring quantizing distortion

O.Sup3.6 Crosstalk test device for

carrier-transmission on coaxial systems O.Sup3.7 A measuring signal (multitone test

signal) for fast measurement of amplitude and phase for telephone type circuits

O.Sup3.8 Guidelines concerning the

measurement ofjitter

ject Storage Specifications (DOSS) See CORBA.

http://www.odmg.org/

Object Definition AllianceODA Avendor

associa-tion established by Oracle which aims to promote and

develop new interactive TV and other multimedia

services and networks that will operate over a

vari-ety of platforms aDA seeks to establish associated

technical standards for these products Vendors

in-clude a number of high-profile financial institutions

and retailers, and computer and media developers

Compaq See video-on-demand

object encapsulationA technique for combining re-lated data and functions into an operational bundle, thus simplifying its use within a larger framework The purpose is not to hide the intrinsic components

of an encapsulated object, but to create a common superset ofcharacteristics that work together and may

be frequently used and reused This technique is one type of modular approach to programming See en-capsulation, obj ect-oriented programming

ANSI Standards OAM&P Abstracts ANSI Standard ANSI Document Title

T1.118-1992 G Interface Specification for Use with the Telecommunications Management

Network T1.204-1997 Lower Layer Protocols for Telecommunications Management Network

Interfaces, Q3 andXInterfaces Tl.208-1997 Upper Layer Protocols for Telecommunications Management Network, Q3 and

XInterfaces T1.209a-1995 Supplement - Network Tones and Announcements

T1.214-1990 A Generic Network Model for Interfaces between Operations Systems and

Network Elements T1.215-1994 Fault Management Messages for Interfaces between Operations Systems and

Network Elements T1.221-1995 In-Service, Nonintrusive Measurement Device Voice Service Measurements T1.224-1992 Protocols for Interfaces between Operations Systems in Different Jurisdictions T1.226-1992 Management of Functions for Signaling System No.7 Network Interconnections T1.227-1995 Extension to Generic Network Model for Interface between Operations Systems

across Jurisdictional Boundaries to Support Fault Management Tl.228-1995 Services to Interfaces between Operations Systems across Jurisdictional

Boundaries to Support Fault Management (Trouble Administration) T1.229-1992 Performance Management Functional Area Services for Interfaces between

Operations Systems and Network Elements Tl.233-1993 Security Framework for Telecommunications Management Network (TMN)

Interfaces T1.240-1996 Generic Network Information Model for Interfaces between Operations Systems

and Network Elements Tl.243-1995 Baseline Security Requirements for the Telecommunications Management

Network T1.240-1996 Generic Network Information Model for Interfaces between Operations Systems

and Network Elements T1.244-1995 Interface Standards for Personal Communications Services (withdrawn)

Tl.246-1995 Operations Systems across Jurisdictional Boundaries to Support Configuration

Management - Customer Account Record Exchange T1.247-1995 Performance Management Functional Area Services and Information Model for

Interfaces between Operations Systems and Network Elements T1.250-1996 Extension to Generic Network Information Model for Interfaces between

Operations Systems and Network Elements to Support Configuration Management - Analog and Narrowband ISDN Customer Service Provisioning Tl.252-1996 Security for the Telecommunications Management Network Directory

Fiber Optics Illustrated Dictionary

object inheritanceAconcept in object-oriented

pro-gramming (OOP) which describes a hierarchical

passing on ofcharacteristics down through associated

objects

Object Linking and EmbeddingOLE A software

system developed by Microsoft Corporation which

allows various applications programs that are

OLE-compatible to share and exchange information It is

an interoperability system that lowers the distinction

between various applications developed by different

vendors so users can integrate the applications files

and environments, and use them more as a suite of

tools than as separate items It further provides

speci-fication guidelines for the interface for

accomplish-ing these tasks OLE is a very good concept, in

prin-ciple, and works well a lot ofthe time Unfortunately,

the various implementations are not yet perfect, as

the OLE-compliant programs and OLE software

pro-grams installed on a system sometimes will clobber

some of the other programs that don't support OLE,

causing odd behaviors and situations where software

has to be reinstalled, or OLE disabled temporarily

As OLE-capability must be incorporated into each

software application by individual developers, there

is some variation as to the completeness and

depend-ability of these implementations

When it works, OLE is a good for developing

docu-ments that take eledocu-ments from a variety of text,

im-age, sound, and other programs and combine them

via links and drag and drop Spreadsheet totals or

sta-tistics can be incorporated into stock offering

docu-ments, images can be incorporated into proposals,

sounds can be incorporated into multimedia

presen-tations, etc without constantly opening and closing

applications and converting various file formats with

external utilities OLE does more than just provide a

way to insert information from one source into

an-other; it further keeps a record of the links so that if

source information in one document is updated, it will

also be updated in subsequently linked documents

OLE is used by various applications in Windows and

Macintosh operating systems See ActiveX

Object Management ArchitectureOMA.An

archi-tectural framework developed by the Object

Manage-ment Group (OMG) to lower the complexity and cost

of developing new software applications See

CORBA, Object Management Group

Object Management Architecture BoardOMAB

A group established in 1996 by the Object

Manage-ment Group (OMG) to oversee the OMG Technical

Process, including the tracking and revision of

tech-nical specifications See CORBA, Object

Manage-mentGroup

Object Management GroupOMG A nonprofit

or-ganization ofover 800 software developers, vendors,

and end users whose aim is to establish the

wide-spread use ofCORBA through global standard

speci-fications Headquartered in Massachusetts and

estab-lished by eight companies in 1989, OMG promotes

the theory and practice of object technology for the

development of distributed computing systems

through a common architectural framework OMG

seeks to establish industry guidelines and object man-agement specifications to further the development of standardized object software, which it hopes will en-courage a heterogenous computing environment across platforms and operating systems See CORBA, Object Management Architecture, Unified Modeling Language http://www.omg.org/

Object Request BrokerORB The communications center ofthe Common Object Request Broker Archi-tecture (CORBA) standard developed by the Object Management Group (ORG) It provides an infrastruc-ture for program objects to intercommunicate, inde-pendent of the techniques used to implement them and the platform on which the software is running Compliance with the ORB provides portability over many different systems The ORB administers objects

so an application need only request an object by name There are now many commercial and freely distrib-utable ORBs See CORBA, Fnorb, Object Manage-ment Group, TAO There is general information on CORBAat

http://www.omg.org/

There is a good list of ORB resources on the Web at http://patriot net/-tvalesky/freecorte html Object Serialization Stream ProtocolOSSP A means to represent objects within a stream Objects are grammatically represented and assigned a handle for use as a reference to the object See byte-stream protocol, Java

Object Services Management components of the Common Object Request Broker Architecture (CORBA) standard developed by the Object Manage-ment Group (OMG) A set of services for facilitating development productivity and consistency of imple-mentation The Object Services provide generic en-vironments for objects to perform their functions, interfaces for the creation of objects, control of ac-cess to the objects, and administration ofthe location ofobjects See CORBA, Object Management Group object-oriented programmingOOP A software development approach that follows a more natural and efficient evolution than many older reinvent-the-wheel approaches to programming To understand the difference between non-object-oriented program-ming and object-oriented programprogram-ming in a simplis-tic way, imagine a toy shop in which each elfis work-ing in a separate little room, each with a separate set oftools, creating some kind oftoy doll At the end of the day, the creations are brought into a central room and it is discovered that some toys have been dupli-cated, none have interchangeable parts, and the end result is only a halfdozen different toys That's pretty much how traditional programming has been done, with an enormous amount of replication of effort Every company writes the same sorting algorithms, there are hundreds of half-baked proprietary editors, and file search and retrieval methods are reinvented

by thousands ofprogrammers on a daily basis It isn't very efficient It isn't even very much fun

Now picture a toy shop in which some general guide-lines are set out for joints and limbs, and in which each toymaker has a magic replicator in which his or

of times Now imagine one of the toymakers is a

mechanical wizard, and another is an artist, able to

make beautiful embellishments At the end ofthe day,

instead ofhaving a dozen toys, a limitless number of

heads and feet, bodies and legs can be shared among

all the toymakers Not only that, but some

particu-larly intricate mechanical parts and some wonderfully

aesthetic ones can be used by all Since guidelines

were set out, the parts are interchangeable The elves

have created the basis for thousands of toys, rather

than just a dozen Assuming unlimited replication of

individual parts, there's no limit to how often each

component can be used That's what object-oriented

programming is, in the ideal sense Once you create

aneye objectand give it certain parameters so that

the color, shape, and various eye characteristics

(con-tact lenses, eyelashes, ability to track a moving shape,

etc.) can be individualized, you don't have to do it

again; you can mix and match it with head, nose, and

hair objects in thousands of different ways

Similarly, in programming it is possible to create

di-rectory, menu, window, and button objects

Object-oriented concepts are not limited to physical

at-tributes; the software can also incorporate more

ab-stract user security objects, sort or fetch objects, and

functions and behavioral characteristics associated

with a type or class of objects

Object-oriented programming is a modular approach

that allows objects to be mixed and matched, or

ar-ranged in hierarchies, and customized to suit an

in-dividual application Once created, they can be

re-used indefinitely This can save development time and

provides the basis for platform-independent software;

it also gives a certain level of consistency to the

in-terface, so users don't have a high learning curve for

interacting with new applications programs.Itfurther

provides the programmer with a number oflevelsof

interaction with an object The developer can use the

object in a transparent way, with the definition ofthe

object encapsulated (bound together as an attribute

or functional unit) by passing messages and

param-eters without worrying about how it was coded, or

the programmer can take apart the object and use its

individual components, or combine it with others to

create a larger functional unit This too is different

from traditional programming In many cases using

someone else's non-object-oriented code involves a

lot ofstudy and adaptation to make it work in another

setting, and it's rarely easy to mix and match parts of

the code so that the characteristics can be inherited

among the different parts In contrast, program

ob-jects can be designed so that their characteristics and

behaviors are known, so they can be immediately

used without a long ramp-up period or restructuring

Object-oriented programming languages are still

evolving Smalltalk is one ofthe first object-oriented

programming environments, developed 20 years ago,

but many common languages currently used in

com-mercial software development are not

object-ori-ented; efforts to create object-oriented versions

oftra-ditionallanguages have not been fully satisfactory

given its obvious advantages of portability and effi-ciency in many contexts

For important and interesting information on taking the object-oriented model to global implementation and distribution, see CORBA and Object Manage-ment Architecture See Open Systems Interconnect, Smalltalk

ODRASee Omnibus Budget Reconciliation Act ODSSee optical burst switching

obscenityObscenity, in its everyday sense, refers to actions or materials which are offensive, repellent,

or vile In a legal sense, it is more specific, as indi-vidual interpretations of what is offensive vary dra-matically Questions involving obscenity often con-flict with individuals' rights and opinions regarding freedom of speech, and thus are important issues on the global Internet See Communications Decency Act of 1996, Electronic Frontier Foundation

OCoperator centralization

OC-nSee optical carrier for definition and chart OCCSee Other Common Carrier

Occam's RazorA maxim well known to scientists, attributed to William of Occam in the 1300s, that it

is vain to do with more what can be done with fewer (or less) It has been restated in many ways, in many contexts, but essentially, in science and in human spheres of activity, the idea is that the simplest ex-planation or one which doesn't require any additional hypotheses is usually the best, and often correct occludeTo block, to obscure or limit from reaching the sight of the viewer For example, a continuous stream of light can be pulsed by periodically occlud-ing the beam See chopper, knife-edge focusocclud-ing, op-tical chopper, Ronchi grating

OCIRovercoat-incident recording

OCPoperator control pane1

OCR1 See optical character recognition 2 Outgo-ing Call Restriction

octalA base eight numbering system utilizing the numerals 0 through 7 See decimal, hexadecimal octathorpSee octothorpe

octet1 A data unit widely used in digital networks

An octet consists of a sequence of eight data bits, sometimes called a byte (which is usually but not al-ways eight bits and thus ambiguous) 2 In Internet Protocol (IP), octets are used as data units to describe

an address or class designation as four octets (32 bits) separated by delimiters See IP address, IF class 3

In RFC descriptions ofpackets, an octet is a data unit for describing packet lengths

octet rule In molecular physics and chemistry, an octet is a completed valance shell of eight electrons

as is common to most elements The octet rule is the manner in which atoms bond to one another as mol-ecules so that valance shells fill to comprise eight electrons There are exceptions, such as the common element hydrogen (H), which requires only two elec-trons to complete its electron shell

octopus, hydraA visually descriptive name for a 25-pair cable common in multiple phone system in-stallations At the far end, the 25-pair wire is organized

Fiber Optics Illustrated Dictionary

into individual connectors (two, four, six, or eight

wires) with phone cord connectors.Anoctopus is

useful for stringing a single wire into a location where

several phone connections are planned

octothorpe, octathorp The #symbol, sometimes

also called pound, hash, crosshatch, or number sign

Itis used as an end signal (or "long" signal) on some

touchtone phone menu systems It represents a

num-ber sign in financial contexts, a suite numnum-ber in postal

addresses, and a sharp in music notation See pound.

ODBC See Open Database Connectivity

ODC See Open Development Consortium

ODMG See Object Database Management Group

onpSee open distributed processing

ODU See optical channel data unit

Odyssey Amedium Earth orbit (MEO) satellite

com-munications system intended to begin service in 1999

with 12 medium Earth orbit (MEO) satellites Planned

services included voice, data, facsimile, and Global

Positioning Service (GPS) The project was

discon-tinued in 1997 and TRW transferred technical

exper-tise to the ICO Global Communications ICONET

when it became a leading ICO shareholder later in

1997 TRW Inc announced that it would tum back

the license it had received for the Odyssey program

to the U.S Federal Communications Commission

(FCC), in order to make the assigned frequencies

available to other communications services See ICO

Global Communications

oersted (symb - Oe, 0) A centimeter-gram-second

(CGS) unit ofmagnetic intensity (field strength) equal

to the intensity of a magnetic field in a vacuum in

which a unit magnetic pole experiences a

mechani-cal force of one dyne in the direction of the field It

can be expressed as10 3 /4pAm·l Named after Hans

Christian 0rsted (sometimes transcribed as Oersted)

See ampere

Oersted (0rsted), Hans Christian (1777-1851) A

Danish physicist and educator who demonstrated the

effects of current on a magnetic needle to a class of

physics students around 1819 He reported on the

magnetic effects ofelectric currents, information that

brought together magnetism and electricity as never

before, and resulted in a change in scientific

think-ing and the development of electric telegraphs in

Eu-rope and America The oersted unit of magnetic

in-tensity is named after him

OFDM See orthogonal frequency division multiplex

off-axis parabolic, off-axis paraboloidal OffAP.In

optics, a geometric configuration used in reflectors

in which the optical or symmetry axis of the

reflec-tor does not pass through the reflecreflec-tor but passes by

nearby The optical axis is parallel to the mechanical

axis, in relation to the curved reflective surface, but

generally falls outside the region of curvature of the

reflective surface at a focal point that is accessible to

the user The parabolic surface is shaped to efficiently

capture incoming rays within a desired field ofview

For scientific applications, the reflectors may be

coated with gold to enhance infrared reflectivity

On-axis and off-On-axis parabolic reflectors are used for

broad spectral range illumination and light-collecting

applications, sometimes in place of optical lenses Parabolic mirrors may also guide and focus beams,

as in spectrometers

OffAP mirrors can produce a point image from a co1-limated beam and eliminate aberrations in very fine diameter optical fibers in spectroscopic applications Multiple OffAPs may be housed in an assembly There is a broad range of commercially available OffAPs for many applications and custom OffAPs may be ordered, but common focal lengths range from about 3 to40in and off-axis distances range from about 1 to 20 in for reflectors between 1 to 8

in diameter See monochromator

off-hook On a phone set, the state of having the plunger or switch-hook in the active or "up" position

so the circuit is connected The term comes from the old wall phones on which the earpiece (receiver) was taken off a curved hook when in use (and when the battery power was engaged) When the phone is first taken off-hook, it alerts the switching exchange to the fact that the caller wants to use a line The switching exchange returns a dial tone to the caller to indicate that the line is available for dialing See on-hook off-peak hours Hours oflow usage.Intelephony, the hours between 11 :00P.M.and 7:00A.M.are designated

as off-peak in many areas, and calling rates are lower The concept also applies to transportation systems, and fewer buses, trains, or subway cars may be in service during these hours

off hours The times outside normal operating or working hours Telephone and Internet services are often discounted in off hours or off-peak hours off the shelf Products and services that are ready to use without any customization Products which can

be readily purchased by anyone walking into a store

or ordering from a catalog, and run with little or no configuration Essentially the same as shrinkwrapped products

office automation Acatchall term for procedures and systems designed to streamline or increase the effi-ciency of business operations, often by installing technology that mayor may not displace human workers In some respects office automation has freed people from drudge work; it is no longer necessary

to have rooms full of"human calculators" sitting and working out sums by hand, but technology has also introduced greater needs for training, storage of in-formation, information retrieval, and other time-con-suming activities that don't necessarily improve qual-ity of life or shorten the work day

Office of Science and Technology Policy OSTP The science policy coordinating group for the Federal Government Executive Branch The OSTP is led by presidentially appointed directors, organized into four divisions: environment, national security and inter-national affairs, science, and technology The OSTP provides expert advice to the President of the United States in matters of science and technology

http://www.whitehouse.gov/WH/EOP/OSTP/htmll

OSTP Info.htrnl Office-of Telecommunications Along with the Of-fice ofTelecommunications Policy, this organization

tions and Information Administration in 1978 as a

result of a reorganization

Office of Telecommunications PolicyOTP

Office of the Director of Telecommunications

RegulationODTR The National Regulatory

Author-ity for telecommunications in Ireland, established

June 1997 under the Telecommunications

Miscella-neous Provision Act 1996 The ODTR administers the

development of a liberal telecom market in

accor-dance with the European Union and Irish law,

allo-cates radio spectrum, and regulates broadcast

trans-missions and telecommunications equipment

OFS LaboratoriesAn international optical lab that

has pioneered the production of optical fibers,

con-nectors, cables, and attenuators The Norcross,

Geor-gia, plant began producing optical fiber in 1976 and

is now the world's largest fiberoptic manufacturing

facility Inaddition to design and fabrication, OFS

publishes a number of technical papers on fiber and

photonic bandgap technologies

In 2002, OFS introduced a fiber design that

incorpo-rates photonic crystal technology to "tune" the

wave-lengths passing through the fiber See photonic

crys-tal

OFX See Open Financial Exchange

OGToutgoingtrunk

ohmA practical unit in the meter-kilogram-second

(MKS) system equal to the resistance of a circuit in

which a potential difference of IV produces a

IAcur-rent Thus, if the values of two of these three are

known, the third can be calculated Named after

Georg Simon Ohm.In 1908 the International

Con-gress established the International ohm as the

resis-tance offered to an unvarying current by a column of

mercury at O°C, 106.3 em long, of a constant

cross-sectional area of 1square mm, and weighing 14.4521

g.Inthe U.S in 1950, Congress defined the ohm as

equal to one thousand million units (109

)ofresistance

See ampere, electromotive force, Ohm's law,

resis-tance, volt

Ohm, Georg Simon(1787-1854) A German

physi-cist who, in 1820, investigated the conducting

prop-erties of various materials He described the flow of

electricity through a conductor and discovered the

relationships among current, resistance, and

electro-motive force, information that greatly influenced

sub-sequent theory and application in electricity See

Ohm's law

Ohm's lawIn any specific direct current electrical

circuit, the strength of the current is directly

propor-tional to the potential difference in the circuit and

in-versely proportional to the resistance Thus, current

(in amperes) equals electromotive force (in volts)

di-vided by resistance (in ohms), or I= EIR See

am-pere, ohm, resistance, volt

OHR See optical handwriting recognition

OLESee Object Linking and Embedding

OLIUOptical Line Interface Unit

OLNSOriginating Line Number Screening

OLToptical line termination

OMOperational Measurement

OMATOperational Measurement and Analysis Tool

OMGSee Object Management Group

OMSNoptical multiservice node

Omnibus Budget Reconciliation Act OBRA

OBRA is a 1993 U.S Congress amendment to the Communications Act of 1932 which preempts state jurisdiction in such a way that individual states no longer regulate rates and entry by companies offer-ing wireless services The federally controlled spec-trum was transferred to the Federal Communications Commission (FCC).Itfurther organized wireless into two categories: commercial mobile radio services (CMRS), including cellular radio services and per-sonal communications services (PCS), and private mobile radio services (PMRS), including public safety and government services See Telecommuni-cations Act of 1932

omnidirectionalEffective in all directions, radiating

in all directions, or receiving from all directions

Functional in many directions without preference to anyone.Anomnidirectional antenna is one which is designed to send or receive signals in a maximum number ofdirections Atheoretical isotropic antenna

is fully omnidirectional and often used as a reference for comparing antenna patterns or effectiveness An omnidirectional speaker directs sound in all direc-tions Since this is structurally difficult to achieve,

~~: ~~~:~i~~:~~~~s~ ~~~:~~?~ ~~:~~~~~.POint-.

omnidirectional antennaAn antenna designed to transceive signals through a wide range ofdirections

Since an antenna's capabilities are detennined by shape and location, it is rarely completely omnidi-rectional, but broad omnidirectionality is achieved by maintaining equal field strength through the horizon-tal plane, and radiating in or out through the vertical plane See isotropic, omnidirectional

omnidirectional microphoneA microphone de-signed to capture sound from all around its location

This is actually less common than directional micro-phones Tape players, camcorders, digitizing sound sample microphones, phoneset microphones, and oth-ers have directional microphones to zero in on the crucial input, so they can screen out extraneous noises and conversations Omnidirectional micro'phones can

be said to capture sound "environments.' OmniWeb One of the earliest commercial Web Browsers, OmniWeb 1.0 was released in March 1995 for NeXTStep platforms by Lighthouse Design, Ltd

Inspite ofbeing a first release, it was a well-designed, full-featured browser, utilizing the Display PostScript and object-oriented capabilities ofNeXTStep.Ithad flexible bookmark and other accessory capabilities not available in other popular browsers until about a year later OmniWeb was subsequently ported to run

on Macintosh Systems by The Omni Group and con-tinues to be enhanced to take advantage ofevolution-arychanges in HTML and related Web languages

OMSGoptical multiservice gateway

on-hookOn a phone set, the state of having the plunger or switch-hook in the inactive, depressed, or

Fiber Optics Illustrated Dictionary

"down" position to interrupt the circuit, so it is not

active while the phone is not being used The term

comes from the old wall phones on which the

ear-piece (receiver) was cradled on a curved hook when

not in use (to conserve battery power) See off-hook

geometric configuration used in reflectors in which

the optical or symmetry axis of the reflector passes

through the reflector On-axis parabolic reflectors are

used for collimating beams and off-axis

paraboloi-dal reflectors are used for broad spectral range

illu-mination and light-collecting applications

Paraboloi-dal reflectors are sometimes used in place ofor in

con-junction with optical lenses Paraboloidal mirrors

may be used to guide and focus beams and OnAPs

have been used in experimental laser propulsion

re-search Higher-precision reflectors may be coated

with gold See off-axis parabolic

link, such as highway, phone trunk, or networking

service The on-ramp is the link between the user's

system and the main system.AnInternet Access

Pro-vider (lAP) can be considered an Internet on-ramp

to frequency shiftkeyin~(FSK), except that no

sig-nal is used for binary "0' (zero) See frequency shift

keying, phase shift keying

ONASee Open Network Architecture

ONACOperations Network Administration Center

ONALOff Network Access Line

minimally functioning, and is largely

automated.ln-teracting with a proceduralized system Auser is said

to be online when he or she logs into a computer or a

network, or accesses an automated phone system 2

To bring a system online is to connect or power it up

so that it is at least minimally functioning 3 To bring

an employee online refers to fitting the person into

an organizational structure within an established

sys-tem of priorities and procedures

ser-vice for providing access to bibliographic records

OPAC can be used to search records based upon

au-thor, title, subject, title keywords, and other search

criteria Many libraries worldwide offer access to

OPAC through Telnet, Web interfaces, or internal

Libsys systems Similar to OPAC is the British

Li-brary Public Catalogue (BLPC); COPAC is a

pub-licly accessible catalog from 20 ofthe largest research

libraries in Ireland and the U.K who are members of

the Consortium of University Research Libraries

(CURL).

ONToptical network terminaVtermination

ONUSee optical network unit

OOPSee object-oriented programming

OPAC I.See Online Public Access Catalog 2 See

outside plant access cabinet

open I Unbounded, having no barriers or extents,

unconcealed, exposed, uncovered, unobstructed

2.Anopen circuit is one not currently connected,

usu-ally because no power is coming to it (as when it is

turned off) A circuit breaker or blown fuse may cre-ate an open circuit 3.Anopen transmission channel

is one that is not currently in use or with channels available so that it may be used with appropriate fa-cilities and authorization.Anopen channel may also imply one that is unsecured, where others can hear any communication that occurs

grounding mechanism, often used in conjunction with fuses and heat coils to guard against possible danger

to people and equipment from large power fluctua-tions Ifvoltage is too high, the wire grounds by arc-ing across a small air gap between carbon blocks mounted on an insulator such as porcelain

telecommunica-tions vendors promoting K56flex modem technology

either depends on air for the propagation of the sig-nals or which is commonly broadcast through the air Radio, shortwave, and microwave transmissions are primarily open air systems

into a system and documented in such a way that third-party vendors can develop equipment and soft-ware applications that tie into that system

ven-dor-neutral, scalable, securable, business-to-business standards effort for the support of electronic com-merce The effort was initiated by a round-table dia-logue by a number of Fortune 500 companies in Oc-tober 1996 The founding participants included prominent firms such as American Express, BASF Corporation, Ford Motor Company, and others The goal was the quick and effective implementation of interoperable Internet-based e-commerce solutions amenable to universal, high-speed access and paper-less transactions In June 1998, CommerceNet as-sumed management of the OBI Consortium to facili-tate standardization efforts

The OBI specification supports purchasing solutions for procuring high-volume, low-dollar, indirect prod-ucts and services OBI was first publicly demon-strated through the OBI Interoperability Showcase at the CommerceNet 99 conference The first version

of OBI was released in March 1997, with V2.1 re-leased in November 1999

Consortium.Anindependent nonprofit organization dedicated to the development of open standards for business-to-business Internet commerce

http://www.openbuy.org/

envi-ronment created by Apple Computer which provides

a means for third-party developers to create telecom-munications applications that interface with the Macintosh operating system (MacOS) Thus, devel-opers can create Internet phone, facsimile, network, and other telecommunications-related products for Macintosh owners

te-lephony software open application processing inter-face (API), part of a system that provides

interoper-spreadsheet, and word processing software, which is

especially useful for digital telephony applications

The interface itself is independent of the application

that provides the formatted data In this way, call

records and statistics can be stored and manipulated

with popular software applications, providing

com-puter-telephone integration and advanced

call-record-ing capabilities

Open Development Consortium ODC.An

admin-istrative concept introduced in November 2000 and

formed early in 2001 to promote open standards for

effective and collaborative exchange ofdevelopment

information The consortium evolved out ofODC

dis-cussion list messages supporting informational

con-cepts related to open development and open source

software

open distributed processing ODP Aframework for

specifying systems, with an emphasis on distributed

systems, defined in ISOIlEC 10746 and lTU-r X.900

as a four-part standardized reference model It is

net-work-independent and may be implemented with

rcP/IP, OSI, NetBIOS, and others See CORBA

Open Financial Exchange OFX Aspecification for

the electronic exchange offinancial data among

busi-nesses, consumers, and financial institutions over the

Internet The specification was jointly developed by

CheckFree, Intuit, and Microsoft in 1997 The

speci-fication supports a wide variety of types of financial

transactions including bill presentation and payment,

banking, investment and stock tracking, pension

ac-count inquiries, and more

In 2000, the OFX specification was made XML

1.0-compliant and certain tax form capabilities were

added A number of development toolkits are

avail-able for creating OFX-compliant applications,

includ-ing JOFX (Java OFX) By late 2001, OFX was

sup-ported by more than 1400 payroll processing,

bro-kerage, and banking firms See JOFX

http://www.ofx.net/

Open Group, The Formerly the Open Software

Foundation, The Open Group is an organization

which aids in the development and implementation

of secure and reliable network infrastructures The

Open Brand is a registration mark (X) awarded by

The Open Group to products which conform to the

standard specifications http://www.opengroup.org/

Open Network Architecture aNA Asystem

devel-oped to encourage third-party vendors to supply

pub-lic phone network products and services Under the

Federal Communication Commission's (FCC's)

ONA, the telephone companies must provide the

same service guarantees and levels to outside

ven-dors' products that use the phone lines, as they use

themselves Network services must be stipulated as

individual services in order to make them available

to unaffiliated Internet Service Providers (ISPs) The

Bell Operating Companies are required to comply

withONA

open officeAnadministrative and physical structure

in which low walls or no walls are favored over high

walls, movable walls are favored over fixed walls,

administrators and employees than in other office designs Open office concepts are designed to pro-mote flexibility and communication

Open Shortest Path First Protocol OSPF A TCP/

IP distributed-computing dynamic routing protocol

in the Interior Gateway Protocol (IGP) family ofpro-tocols, developed by the OSPF working group ofthe Internet Engineering Task Force (IETF) OSPF dis-tributes routing information within a single autono-mous system based upon link-state technology (a dif-ferent approach from Bellman-Ford internet routing) OSPF includes explicit support for Classless Inter-Domain Routing (CIDR) and the tagging of exter-nally-derived routing information OSPF supports routing update authentication and IP multicast update sending/receiving OSPF is a responsive protocol with low traffic overhead

Routing is based upon destination information in IP packet headers without further encapsulat.ion OSPF detects and responds to topological changes, calcu-lating new loop-free routes after a short period of convergence See Hello Protocol, link state advertise-ment

open skiescolloq Regulatory policies that are

lib-eral enough to allow private use Prior to 1972, the Federal Communications Commission (FCC) did not permit private American satellites to be launched for commercial communications It then opened the doors on private domestic satellite launchings and op-erations, a move that created an opportunity for new competitive services to be established.Melis one

of the companies that got its start partly through rec-ognizing and taking advantage of the opportunities presented by these openings

Open Software Foundation OSF This has now be-come the Open Group See Open Group

http://www.opengroup.orgl open systemAnopen computer system is one which has few security barriers Passwords may not be needed or individual users' directories may be open

to all users In many ways the Unix operating sys-tem and the Internet global network have been de-veloped with an effort to keep them open and acces-sible; some people advocate that all systems should

be that way

Open Systems Interconnection OSI.Animportant layered architecture specification released as a stan-dard by the International Organization for Stanstan-dard- Standard-ization (ISO) OSI is designed to facilitate commu-nications development between computer equipment and network software Many vendors have opted to support this standard Essentially, the communication

is mapped onto seven layers as shown in the ISO/ Open Systems Interconnection Reference Models chart See ISO/OSI Reference Model for more infor-mation

Open Systems Networking Initiative OSN Atrade organization promoting and supporting open network technologies such as high-capacity storage solutions for enterprise-level systems The organization was founded by Cisco Systems, Quantum Corporation,