39210 IEEE Dictionary IEEES
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`INTERACTIVE
`
`IEEE 100
`The Authoritative Dictionary of
`IEEE Standards Terms
`
`Seventh Edition
`
`Published by
`Standards Information Network
`IEEE Press
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`39210 IEEE Dictionary IEEES
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`INTERACTIVE
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`Trademarks and disclaimers
`
`IEEE believes the information in this publication is accurate as of its publication date; such information is subject
`to change without notice. IEEE is not responsible for any inadvertent errors.
`
`Other tradenames and trademarks in this document are those of their respective owners.
`
`The Institute of Electrical and Electronics Engineering, Inc.
`3 Park Avenue, New York, NY, 10016-5997, USA
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`Copyright 䉷 2000 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published
`December 2000. Printed in the United States of America.
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`No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without
`the prior written permission of the publisher.
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`Print: ISBN 0-7381-2601-2
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`See other standards and standards-related product listings at: http://standards.ieee.org/
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`The publisher believes that the information and guidance given in this work serve as an enhancement to users,
`all parties must rely upon their own skill and judgement when making use of it. The publisher does not assume
`any liability to anyone for any loss or damage caused by any error or omission in the work, whether such error
`or omission is the result of negligence or any other cause. Any and all such liability is disclaimed.
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`This work is published with the understanding that the IEEE is supplying information through this publication,
`not attempting to render engineering or other professional services. If such services are required, the assistance
`of an appropriate professional should be sought. The IEEE is not responsible for the statements and opinions
`advanced in this publication.
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`

`39210 IEEE Dictionary IEEES
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`INTERACTIVE
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`Contents
`
`Introduction
`
`How to Use This Dictionary
`
`Categories
`
`Trademarks
`
`The Authoritative Dictionary of IEEE Standards Terms
`
`Abstracts and Sources
`
`Non-IEEE Standards Sources
`
`v
`
`vi
`
`vi
`
`ix
`
`1
`
`1294
`
`1351
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`39210 IEEE Dictionary IEEES
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`
`Introduction
`
`IEEE standards establish an authoritative common language that defines quality and sets technical criteria.
`By guaranteeing consistency and conformity through open consensus, IEEE standards add value to prod-
`ucts, facilitate trade, drive markets, and ensure safety. That’s why leading companies, organizations, and
`industries around the globe rely on them.
`
`Critical components of this common language are the terms and definitions that are at the foundation of
`the vast body of IEEE standards. In the past decade alone, hundreds of terms — describing the latest tools,
`techniques, and best practices — have been added to the lexicon of IEEE standards.
`
`In this newly updated Authoritative Dictionary of IEEE Standards Terms, professional experts and stu-
`dents alike will gain an in-depth understanding and appreciation for the breadth of coverage of IEEE
`standards terms and definitions not found in any other single source.
`
`The seventh edition of IEEE 100 has been revised to include nearly 35 000 technical terms and definitions
`from over 800 standards — covering areas such as power and energy, communications, information tech-
`nology, and transportation systems. In addition to an extensive list of widely used acronyms and abbre-
`viations, this new edition also contains detailed abstracts of each term’s associated standard(s). What’s
`more, all definitions are augmented by a combination of indispensable information, including:
`
`♦ Preferred and popular usage of each term
`♦ Variations in meanings among different technical specialties
`♦ Cross-indexing to related works
`♦ Key explanatory notes for further term clarification
`
`In preparing this latest edition of the Dictionary, we realized that the standards community desired more
`than just a compilation of IEEE standardized terms and definitions. They needed an authoritative resource
`created by the organization that develops and produces the standards from which the terms and definitions
`are derived — the IEEE. In addition, we determined the Dictionary needed to be not only user friendly,
`but also rich in information. In other words, it needed to be the Authoritative Dictionary of IEEE Standards
`Terms.
`
`Susan K. Tatiner
`Director, IEEE Standards Publishing Programs
`
`IEEE Standards Project Editors for the seventh edition:
`Kim Breitfelder
`Don Messina
`
`Additional assistance was provided by the IEEE Standards editorial staff.
`
`The Authoritative Dictionary of IEEE Standards Terms
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`39210 IEEE Dictionary IEEES
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`How to Use This Dictionary
`
`The terms defined in the Dictionary are listed in letter-by-letter alphabetical order. Spaces are ignored in
`this style of alphabetization, so cable value will come before cab signal. Descriptive categories associated
`with the term in earlier editions of the Dictionary will follow the term in parentheses. New categories
`appear after the definitions (see Categories, below), followed by the designation of the standard or stan-
`dards that include the definition. If a standard designation is followed by the letter s, it means that edition
`of the standard was superseded by a newer revision and the term was not included in the revision. If a
`designation is followed by the letter w, it means that edition of the standard was withdrawn and not
`replaced by a revision. A bracketed number refers to the non-IEEE standard sources given in the back
`of the book.
`
`Abstracts of the current set of approved IEEE standards are provided in the back of the book. It should
`be noted that updated information about IEEE standards can be obtained at any time from the IEEE
`Standards World Wide Web site at http://standards.ieee.org/.
`
`Categories
`
`The category abbreviations that are used in this edition of the Dictionary are defined below. This infor-
`mation is provided to help elucidate the context of the definition. Older terms for which no category could
`be found have had the category Std100 assigned to them. Note that terms from sources other than IEEE
`standards, such as the National Electrical Code威 (NEC威) or the National Fire Protection Association,
`may not be from the most recent editions; the reader is cautioned to check the latest editions of all sources
`for the most up-to-date terminology.
`
`Categories sorted by abbreviation
`
`AES
`AHDL
`AMR
`AP
`ATL
`BA
`BT
`C
`CAS
`CE
`CHM
`COM
`CS
`DA
`DEI
`DESG
`DIS
`ED
`EDU
`EEC
`ELM
`EM
`EMB
`EMC
`GRS
`GSD
`IA
`IE
`II
`IM
`IT
`
`vi
`
`aerospace and electronic systems
`computer—Analog Hardware Descriptive Language
`automatic meter reading and energy management
`antennas and propagation
`computer—Abbreviated Test Language for All Systems
`computer—bus architecture
`broadcast technology
`computer
`circuits and systems
`consumer electronics
`components, hybrids, and manufacturing technology
`communications
`control systems
`computer—design automation
`dielectrics and electrical insulation
`dispersed energy storage and generation
`computer—distributed interactive simulation
`electron devices
`education
`electrical equipment and components
`electricity metering
`engineering management
`engineering in medicine and biology
`electromagnetic compatibility
`geoscience and remote sensing
`graphic symbols and designations
`industry applications
`industrial electronics
`information infrastructure
`instrumentation and measurement
`information theory
`
`The Authoritative Dictionary of IEEE Standards Terms
`
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`Stand
`Long
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`39210 IEEE Dictionary IEEES
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`IVHS
`LEO
`LM
`MAG
`MIL
`MM
`MTT
`NEC
`NESC
`NFPA
`NI
`NIR
`NN
`NPS
`ODM
`OE
`PA
`PE
`PEL
`PQ
`PSPD
`PV
`QUL
`R
`RA
`REM
`RL
`S&P
`SB
`SE
`SMC
`SP
`Std100
`SUB
`SWG
`T&D
`TF
`TRR
`TT
`UFFC
`VT
`
`intelligent vehicle highway systems
`lasers and electro-optics
`computer—local and metropolitan area networks
`magnetics
`military
`computer—microprocessors and microcomputers
`microwave theory and techniques
`National Electrical Code
`National Electrical Safety Code
`National Fire Protection Association
`nuclear instruments
`non-ionizing radiation
`neural networks
`nuclear and plasma sciences
`computer—optical disk and multimedia platforms
`oceanic engineering
`computer—portable applications
`power engineering
`power electronics
`power quality
`power surge protective devices
`photovoltaics
`quantities, units, and letter symbols
`reliability
`robotics and automation
`rotating electrical machinery
`roadway lighting
`computer—security and privacy
`stationary batteries
`computer—software engineering
`systems, man, and cybernetics
`signal processing
`Standard 100 legacy data
`substations
`power switchgear
`transmission and distribution
`time and frequency
`transformers, regulators, and reactors
`test technology
`ultrasonics, ferroelectrics, and frequency control
`vehicular technology
`
`Categories sorted by name
`
`aerospace and electronic systems
`antennas and propagation
`automatic meter reading and energy management
`broadcast technology
`circuits and systems
`communication
`components, hybrids, and manufacturing technology
`computer
`computer—Abbreviated Test Language for All Systems
`computer—Analog Hardware Descriptive Language
`computer—bus architecture
`computer—design automation
`computer—distributed interactive simulation
`computer—local and metropolitan area networks
`computer—microprocessors and microcomputers
`computer—optical disk and multimedia platforms
`computer—portable applications
`computer—security and privacy
`computer—software engineering
`consumer electronics
`
`The Authoritative Dictionary of IEEE Standards Terms
`
`AES
`AP
`AMR
`BT
`CAS
`COM
`CHM
`C
`ATL
`AHDL
`BA
`DA
`DIS
`LM
`MM
`ODM
`PA
`S&P
`SE
`CE
`
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`39210 IEEE Dictionary IEEES
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`control systems
`dielectrics and electrical insulation
`dispersed energy storage and generation
`education
`electrical equipment and components
`electricity metering
`electromagnetic compatibility
`electron devices
`engineering in medicine and biology
`engineering management
`geoscience and remote sensing
`graphic symbols and designations
`industrial electronics
`industry applications
`information infrastructure
`information theory
`instrumentation and measurement
`intelligent vehicle highway systems
`lasers and electro-optics
`magnetics
`microwave theory and techniques
`military
`National Electrical Code
`National Electrical Safety Code
`National Fire Protection Association
`neural networks
`non-ionizing radiation
`nuclear and plasma sciences
`nuclear instruments
`oceanic engineering
`photovoltaics
`power electronics
`power engineering
`power quality
`power switchgear
`quantities, units, and letter symbols
`reliability
`roadway lighting
`robotics and automation
`rotating electrical machinery
`signal processing
`Standard 100 legacy data
`stationary batteries
`substations
`surge-protective devices
`systems, man, and cybernetics
`test technology
`time and frequency
`transformers, regulators, and reactors
`transmission and distribution
`ultrasonics, ferroelectrics, and frequency control
`vehicular technology
`
`CS
`DEI
`DESG
`EDU
`EEC
`ELM
`EMC
`ED
`EMB
`EM
`GRS
`GSD
`IE
`IA
`II
`IT
`IM
`IVHS
`LEO
`MAG
`MTT
`MIL
`NEC
`NESC
`NFPA
`NN
`NIR
`NPS
`NI
`OE
`PV
`PEL
`PE
`PQ
`SWG
`QUL
`R
`RL
`RA
`REM
`SP
`Std100
`SB
`SUB
`PSPD
`SMC
`TT
`TF
`TRR
`T&D
`UFFC
`VT
`
`viii
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`39210 IEEE Dictionary IEEES
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`Trademarks
`
`The following is a list of trademarks that may be used in IEEE 100: The Authoritative Dictionary of
`IEEE Standards Terms.
`
`802 is a registered trademark of the Institute of Electrical and Electronics Engineers, Inc.
`
`ABBET is a registered trademark of the Institute of Electrical and Electronics Engineers, Inc.
`
`Adobe is a trademark of Adobe Systems Incorporated.
`
`Analog devices is a trademark of Analog Devices, Inc.
`
`Appletalk is a registered trademark of Apple Computer, Inc.
`
`BOCA is a registered trademark of Building Officials and Code Administrators International, Inc.
`
`BOOM is a registered trademark of Fakespace, Inc.
`
`Centronics is a registered trademark of Genicom Corporation.
`
`CompactPCI is a registered trademark of the PCI Industrial Computer Manufacturers Group.
`
`Cray is a registered trademark of Cray Research, Inc.
`
`DSSI is a registered trademark of Discreet Surveillance Systems.
`
`Futurebus⫹ is a registered trademark of the Institute of Electrical and Electronics Engineers, Inc.
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`IBM is a registered trademark of International Business Machines, Inc.
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`Intel386 is a trademark of Intel Corporation.
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`Life Safety Code is a registered trademark of the National Fire Protection Association.
`
`Mylar is a registered trademark of E.I. du Pont de Nemours and Company.
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`National Electrical Code is a registered trademark of the National Fire Protection Association.
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`NEC is a registered trademark of the National Fire Protection Association.
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`National Electrical Safety Code is a registered trademark and service mark of the Institute of Electrical
`and Electronics Engineers, Inc.
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`NESC is a registered trademark and service mark of the Institute of Electrical and Electronics Engineers,
`Inc.
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`Netbios is a registered trademark of International Business Machines, Inc.
`
`Nomex is a registered trademark of E. I. Dupont de Nemours and Company.
`
`NuBus is a registered trademark of Texas Instruments, Inc.
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`OpenBoot is a trademark of Sun Microsystems, Inc.
`
`Open Software Foundation, OSF, and the OSF logo are registered trademarks of the Open Software
`Foundation, Inc.
`
`PostScript is a trademark of Adobe Systems Incorporated.
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`POSIX is a registered certification mark of the Institute of Electrical and Electronics Engineers, Inc.
`
`PS/2 is a registered trademark of International Business Machines, Inc.
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`SCSI is a registered trademark of SCSI Solutions.
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`SDI is a registered trademark of Maurice Siebenberg.
`
`SPARC is a registered trademark of SPARC International, Inc.
`
`SPARCstation is a trademark of SPARC International, Inc.
`
`SPAsystem is a registered trademark of the Institute of Electrical and Electronics Engineers, Inc.
`
`Stylized 8 (Futurebus⫹) is a registered trademark of the Institute of Electrical and Electronics Engineers,
`Inc.
`
`Sun Microsystems is a registered trademark of Sun Microsystems, Inc.
`
`TURBOchannel is a registered trademark of Digital Equipment Corporation.
`
`Uniform Building Code is a trademark of the International Conference of Building Officials (ICBO).
`
`UNIX is a registered trademark in the United States and other countries, licensed exclusively through
`X/Open Company Limited.
`
`VAX is a registered trademark of Digital Equipment Corporation.
`
`VAXBI is a registered trademark of Digital Equipment Corporation.
`
`Verilog is a registered trademark of Cadence Design Systems, Inc.
`
`Velcro is a registered trademark of Velcro Industries B. V.
`
`Windows is a trademark of Microsoft Corporation.
`
`X/Open is a registered trademark and the “X” device is a trademark of X/Open Company, Ltd.
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`R
`
`rabbet, mounting See: mounting rabbet.
`RAC See: reflective array compressor.
`raceway (1) Any channel designed expressly and used solely
`for holding conductors.
`(NESC) C2-1997
`(2) (raceway systems for Class 1E circuits for nuclear
`power generating stations) Any channel that is designed and
`used expressly for supporting wires, cables, or bus bars. Race-
`ways consist primarily of, but are not restricted to, cable tray,
`conduits, and wireways.
`(PE/NP/IC) 628-1987r, 848-1996, 384-1992r, 634-1978w
`(3) (electric systems) Any channel for enclosing, and for
`loosely holding wires, cables, or busbars in interior work that
`is designed expressly for, and used solely for, this purpose.
`Note: Raceways may be of metal or insulating material and
`the term includes rigid metal conduit, rigid nonmetallic con-
`duit, flexible metal conduit, electrical metallic tubing, under-
`floor raceways, cellular concrete-floor raceways, cellular
`metal-floor raceways, surface metal raceways, structural
`raceways, wireways and busways, and auxiliary gutters or
`moldings.
`(NESC) [86]
`(4) An enclosed channel designed expressly for holding
`wires, cables or busbars with additional functions as permitted
`in this Code.
`(NESC/NEC) [86]
`raceway penetration (raceway systems for Class 1E circuits
`for nuclear power generating stations) An opening for a
`raceway in a floor or wall to permit passage of cables from
`one side to the other. The raceway may or may not be con-
`tinuous through the opening.
`(PE/NP) 628-1987r
`raceway system (raceway systems for Class 1E circuits for
`nuclear power generating stations) An integrated assembly
`of raceways, fittings, supports, accessories, and anchorages.
`(PE/NP) 628-1987r
`rachet demand (power operations) The maximum past or
`present demands that are taken into account to establish bill-
`ings for previous or subsequent periods.
`(PE/PSE) 858-1987s
`rachet demand clause (power operations) A clause in a rate
`schedule that provides that maximum past or present demands
`be taken into account to establish billings for previous or sub-
`sequent periods.
`(PE/PSE) 858-1987s
`rack (1) (control boards, panels, and racks) A framework,
`constructed of rails or steel members, for mounting an assem-
`bly of modules for monitoring, measuring, and controlling
`remotely operated systems.
`(PE/NP) 420-1982
`(2) (electronic) A protective enclosure to house modules,
`backplane(s), I/O connector assemblies, internal cables, and
`other electronic, mechanical, and thermal devices. Synonyms:
`rack; cabinet; box; box; cabinet; rack.
`(C/BA) 14536-1995
`rack, traveler See: traveler rack.
`racon (navigation aid terms) A radar beacon that returns a
`coded signal providing identification of the beacon as well as
`range and bearing. See also: radar beacon.
`(AES/GCS) 172-1983w
`rad (photovoltaic power system) An absorbed radiation unit
`equivalent to 100 ergs/gram of absorber. See also: photovol-
`taic power system.
`(AES) [41]
`radar (1) (navigation aid terms) A device for transmitting
`electromagnetic signals and receiving echoes from objects of
`interest (targets) within its volume of coverage. Presence of
`a target is revealed by its echo or its transponder reply. Ad-
`ditional information about a target provided by a radar in-
`cludes one or more of the following: distance (range), by the
`elapsed time between transmissions of the signal and recep-
`tion of the return signal; direction, by use of directive antenna
`patterns; rate of change of range, by measurement of Doppler
`shift; description or classification of target, by analysis of ech-
`oes and their variation with time. The name radar was origi-
`nally an acronym for Radio Detection and Ranging. Note:
`
`Some radars can operate in a passive mode, in which the
`transmitter is turned off and information about targets is de-
`rived by receiving radiation emanating from the targets them-
`selves or reflected by the targets from external sources.
`(AES/GCS) 172-1983w
`(2) An electromagnetic system for the detection and location
`of objects that operates by transmitting electromagnetic sig-
`nals, receiving echoes from objects (targets) within its volume
`of coverage, and extracting location and other information
`from the echo signal. Notes: 1. Radar is an acronym for radio
`detection and ranging. 2. Radar equipment can be operated
`with the transmitter turned off, as a passive direction finder
`on sources radiating within the band of the receiving system.
`See also: passive angle tracking.
`(AES) 686-1997
`(3) A device that radiates electromagnetic waves and utilizes
`the reflection of such waves from distant objects to determine
`their existence or position.
`(IA/MT) 45-1998
`radar-absorbent material (RAM) Material used to reduce the
`radar cross section of an object. Note: Also used in anechoic
`chambers to reduce reflection from the walls.
`(AES) 686-1997
`
`radar altimeter See: radio altimeter.
`radar astronomy That branch of astronomy that uses radar to
`study astronomical objects.
`(AP/PROP) 211-1997
`radar backscattering cross-section Radar scattering cross-sec-
`tion as determined for coincident transmitter and receiver lo-
`cations. See also: scattering cross section.
`(AP/PROP) 211-1997
`radar beacon (navigation aid terms) A transponder used for
`replying to interrogations from a radar. See also: secondary
`radar.
`(AES/GCS) 686-1997, 172-1983w
`radar bearing (navigation aid terms) A bearing obtained by
`a radar.
`(AES/GCS) 172-1983w
`radar camouflage The art, means, or result of concealing the
`presence of the nature of an object from radar detection by
`the use of coverings or surfaces that considerably reduce the
`radio energy reflected toward a radar. See also: radar.
`(EEC/PE) [119]
`radar cross section (RCS) (1) For a given scattering object,
`upon which a plane wave is incident, that portion of the scat-
`tering cross section corresponding to a specified polarization
`component of the scattered wave. See also: scattering cross
`section.
`(AP/ANT) 145-1993
`(2) A measure of the reflective strength of a radar target; usu-
`ally represented by the symbol ␴ and measured in square
`meters. RCS is defined as 4␲ times the ratio of the power per
`unit solid angle scattered in a specified direction of the power
`unit area in a plane wave incident on the scatterer from a
`specified direction. More precisely, it is the limit of that ratio
`as the distance from the scatterer to the point where the scat-
`tered power is measured approaches infinity. Note: Three
`cases are distinguished:
`a) Monostatic or backscatter RCS when the incident and per-
`tinent scattering directions are coincident but opposite in
`sense.
`b) Forward-scatter RCS when the two directions and senses
`are the same.
`c) Bistatic RCS when the two directions are different. If not
`identified, RCS is usually understood to refer to case a).
`In all three cases, radar cross section of a specified target
`is a function of frequency, transmitting and receiving po-
`larizations, and target aspect angle (except for a sphere).
`For some applications, e.g., statistical detection analyses,
`it is described by its average value (or sometimes its me-
`dian value) and statistical characteristics over an appro-
`priate range of one or more of those parameters.
`Synonyms: backscatter cross section; bistatic-scatter cross
`section; effective echoing area;
`forward-scattering cross
`section.
`(AES) 686-1997
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`radar display
`
`907
`
`radial-unbalance torque
`
`radar display The visual representation of radar output data.
`See individual definitions and illustrations of various radar
`display formats in the table below. Note: The letter designa-
`tions from A to P, plus R, for radar display formats were
`devised in the years during and following WWII in an effort
`to standardize nomenclature. Several of these letter designa-
`tions are now rarely if ever used, as noted in the individual
`definitions, but they are still found in some technical litera-
`ture. The additional designations of plan-position indicator
`(PPI) and range-height indicator (RHI) are also defined. The
`standardized type designations do not cover all possible dis-
`play formats.
`(AES) 686-1997
`radar duplexing assembly See: circulator; transmit-receive
`switch; duplexer.
`radar equation A mathematical expression that relates the
`range of a radar at which specific performance is obtained to
`the parameters characterizing the radar, target, and environ-
`ment. Note: The parameters in the radar equation can include
`the transmitter power, antenna gain and effective area, fre-
`quency, radar cross section of the target, range to the target,
`receiver noise figure, signal-to-noise ratio required for detec-
`tion, losses in the radar system, and the effects of the prop-
`agation path. Synonyms: radar range equation; range equa-
`tion.
`(AES) 686-1997
`radar fix (navigation aid terms) A position fix established by
`means of radar data.
`(AES/GCS) 172-1983w
`radar letter designations (radar frequency bands) The radar
`letter designations are consistent with the recommended no-
`menclature of the International Telecommunications Union
`(ITU), as shown in Table 2, below. Note that the high fre-
`quency (HF) and the very high frequency (VHF) definitions
`are identical in the two systems. The essence of the radar
`nomenclature is to subdivide the existing ITU bands, in ac-
`cordance with radar practice, without conflict or ambiguity.
`The letter band designations are not to be construed as being
`a substitute for the specific frequency limits of the frequency
`bands. The specific frequency limits are to be used when ap-
`propriate, but when a letter designation of a radar-frequency
`band is called for, those of Table 1, below, are to be used.
`The letter designations described in IEEE Std 521-1984 are
`designed for radar usage and are used in current practice.
`They are not meant to be used for other radio or telecom-
`munication purposes, unless they pertain to radar. The letter
`designations for Electronic Countermeasure operations as de-
`scribed in Air Force Regulation No 55-44, Army Regulation
`No 105-86, and Navy OPNAV Instruction 3430.9B are not
`consistent with radar practice and are not used to describe
`radar-frequency bands.
`
`(AES/RS) 521-1984r
`radar performance figure The ratio of the pulse power of the
`radar transmitter to the power of the minimum signal detect-
`able by the receiver. Note: Now seldom used as a measure of
`performance.
`(AES) 686-1997
`radar range equation See: radar equation.
`radar reflectivity A measure of backscattering from an inho-
`mogeneous medium, defined as radar cross-section (RCS) per
`unit volume. Frequently used in radar measurements of me-
`teorological phenomena.
`(AP/PROP) 211-1997
`radar relay Equipment for relaying the radar video and appro-
`priate synchronizing signals to a remote location.
`(AES) 686-1997
`
`radar responder beacon See: racon.
`radar shadow Absence of radar illumination because of an in-
`tervening reflecting, diffracting, or absorbing object. Note:
`The shadow is manifested on the display by the absence of
`blips from targets in the shadow area.
`(AES) 686-1997
`radar transmitter The transmitter portion of a radio detecting
`and ranging system.
`(AP/VT/ANT) 145-1983s, [37]
`radial (1) (navigation) (navigation aid terms) One of a num-
`ber of lines of position defined by an azimuthal navigation
`facility; the radial is identified by its bearing (usually the mag-
`netic bearing) from the facility.
`(AES/GCS) 172-1983w
`
`(2) An azimuth where field strength measurements are taken,
`starting near the array and extending to well into the far field.
`Measurements along a radial can be used to establish the ra-
`diation in a certain azimuth after allowing for changes other
`than ground conductivity, such as near field effects, temper-
`ature changes, loss or gain due to elevation changes, shadow
`losses and absorption, and other effects.
`(T&D/PE) 1260-1996
`
`radial air gap See: air gap.
`radial-blade blower (rotating machinery) A fan made with
`flat blades mounted so that the plane of the blades passes
`through the axis of rotation of the rotor. See also: fan.
`(PE) [9]
`
`radial distribution feeder See: radial feeder.
`radial feeder A feeder supplying electric energy to a substation
`or a feeding point that receives energy by no other means.
`Note: The normal flow of energy in such a feeder is in one
`direction only. See also: center of distribution.
`(T&D/PE) [10]
`radial ground A conductor connection by which separate elec-
`trical circuits or equipment are connected to earth at one
`point. Sometimes referred to as a star ground.
`(IA/PSE) 1100-1999
`radially outer coil side See: bottom-coil slot.
`radial magnetic pull (rotating machinery) The radial force
`acting between rotor and stator resulting from the radial dis-
`placement of the rotor from magnetic center. Note: Unless
`other conditions are specified, the value of radial magnetic
`pull will be for no load and rated voltage, and for rated no
`load field current and rated frequency as applicable.
`(PE) [9]
`radial overfilled launch A launch condition created when a
`multimode optical fiber is illuminated by the coherent optical
`output of a source operating in its lowest-order transverse
`mode in a manner that excites predominantly the radial modes
`of the multimode fiber.
`(C/LM) 802.3-1998
`radial power factor (paper-insulated power cable) The power
`factor of individual insulating tapes of a power cable as a
`function of the radial location of the insulating tapes through
`the insulation wall.
`(PE/IC) 83-1963w
`radial probable error (RPE) See: circular probable error.
`radial sensitivity The counting rate of a Geiger-Mueller counter
`as a function of radial position across the window of an end-
`window or pancake Geiger-Mueller counter.
`(NI/NPS) 309-1999
`radial system A system in which independent feeders branch
`out radially from a common source of supply. See also: di-
`rect-current distribution; alternating-current distribution.
`(T&D/PE) [10]
`radial-time-base display See: plan-position indicator.
`radial transfer The transmission of information between a pe-
`ripheral unit and a unit of equipment that is more central than
`that of the peripheral unit using a connection that is dedicated
`to that peripheral unit. See also: peripheral transfer.
`(C) 610.10-1994w
`radial transmission feeder See: radial feeder.
`radial transmission line (waveguide) A pair of parallel con-
`ducting planes used for propagating waves whose phase
`fronts are concentric coaxial circular cylinders having their
`common axis normal to the planes; sometimes applied to ta-
`pered versions, such as biconical lines.
`(MTT) 146-1980w
`radial type A unit substation which has a single stepdown trans-
`former and which has an outgoing section for the connection
`of one or more outgoing radial (stub end) feeders.
`(PE/TR) C57.12.80-1978r
`radial-unbalance torque (1) (laser maser) A unit of angular
`measure equal to the angle subtended at the center of a circle
`by an arc whose length is equal to the radius of the circle.
`One (1) radian ⌬ 57.3 degrees; 2␲ radians ⫽ 360 degrees.
`(LEO) 586-1980w
`
`Short
`Stand
`Long
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`39210 IEEE Dictionary IEEES
`
`radian
`
`908
`
`Table 1
`Standard Radar-Frequency Letter Band Nomenclature
`
`BATCH
`
`radiance
`
`Specific Frequency Ranges for
`Radar Based on ITU Assignments for
`Region 2, see Note (1)
`Note (2)
`138 MHz–144 MHz
`216 MHz–225 MHz
`420 MHz–450 MHz (Note 4)
`890 MHz–942 MHz (Note 5)
`1215 MHz–1400 MHz
`2300 MHz–2500 MHz
`2700 MHz–3700 MHz
`5250 MHz–5925 MHz
`8500 MHz–10680 MHz
`13.4 GHz–14.0 GHz
`15.7 GHz–17.7 GHz
`24.05 GHz–24.25 GHz
`33.4 GHz–36.0 GHz
`59 GHz–64 GHz
`76 GHz–81 GHz
`92 GHz–100