HARGRAVE’S
`COMMUNICATIONS DICTIONARY
`
`Frank Hargrave
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`® IEEE
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`PRESS
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`@
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`TheInstitute of Electrical and Electronics Engineers, Inc., New York
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`© 2001 bythe Institute of Electrical and Electronics Engineers, Inc.
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`All rights reserved. Nopart of this book may be reproducedin any form,
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`Printed in the United States of America.
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`ISBN 0-7803-6020-6
`IEEE Order No. PC5869
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`Library of Congress Cataloging-in-Publication Data
`
`Hargrave, Frank.
`Hargrave’s communications dictionary.
`/ Frank Hargrave.
`p.
`cm.
`Includesindex.
`ISBN 0-7803-6020-6
`1. Telecommunication—Dictionaries.
`TK5102.H37 2000
`621.382'03—dc21
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`I. Title.
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`00-061416
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`IEEE 1284
`
`imaginary number
`260
`IIR Anabbreviation ofInfinite Impulse Response.
`IIR Filter An abbreviation ofInfinite Impulse ResponseFilter.
`IISP An abbreviation ofInterim Inter-switch Signaling Protocol.
`ILD Anabbreviation of Injection Laser Diode.
`illegal In computer terminology, a term that signifies an elementor
`procedurethatis not allowed because it is impossible or would pro-
`duce invalid results. For example, an 8-bit characteris illegal in a
`system thatis designed for 7-bit ASCII.(It’s not possible to put an 8-
`bit characterinto a 7-bit long field.)
`
`IEEE 1284—an enhancedparallel port standard based on boththe en-
`hancedparallel port (EPP) and the extended capabilities port (ECP)
`strategies. See also enhanced parallel port (EPP) and extended ca-
`pabilities port (ECP).
`IEEE 1394—a 1995 serial businterface standard offering high-speed
`communications and isochronousreal-time data services for Macin-
`tosh and IBM PCs.It is meant to be a replacement of the ADB, RS-
`232, RS-422, SCSI, and even theparallel port. Features include the
`following:
`© There are data transfer rates between devices of 100, 200, or 400
`Mbps, with a plannedincrease to 1.2 Gbps.
`© Cable is 6 conductors with lengths to 5 m.
`illegal character A combination ofbits (character), that is not valid
`© It can supply up to 60 watts of power, allowing low-consumption
`in a particular system accordingto its specification (such as with re-
`devices to operate without a separate powercord.
`spectto a specified alphabet, a particular pattern ofbits, a rule offor-
`© It can daisy-chain up to 63 devicesin a treelike structure (as op-
`mation, or a check code), e.g., any 8-bit ASCII character with a most
`posed to SCSI’s linear structure).
`significant bit of one. (Jt may be a valid extended ASCII character,
`© Nobusterminatoris required.
`however.) Also called false character, forbidden character, improper
`© It allows peer-to-peer device communication, such as communi-
`character, unallowable character, and unused character.
`cation between a scannerandaprinter, to take place without us-
`ing system memory or the computeritself.
`IM (1) An abbreviation of Intensity Modulation. (2) An abbrevia-
`tion of InterModulation.
`© Each device identifies itself dynamically (that is, it will not re-
`quire dip switch or jumpersettings).
`IMAC An acronym for Isochronous Media Access Control.
`¢ It supports plug-and-play (PnP) andallows connection anddis-
`connection of devices without interrupting system operation.
`image (1) A fully processed unit of operational information thatis
`ready for transmission, execution, or use. Examples include:
`Also called Firewire, High Performance Serial Bus, andi.Link. See
`also Access bus and Universal Serial Bus (USB).
`¢ Anexact copy of a computer’s working RAM is transferred to a
`secondary storage device such as a diskette.
`TIEN Anabbreviation of Internet Experimental Notes.
`¢ A file, when loadedinto the control storage ofa unit, determines
`TEPG An abbreviation of Internet Engineering and Planning Group.
`the operations ofthat unit.
`(2) A graphic, which may contain pictures and/ortext. It may be rep-
`IES (1) An abbreviation of Inter-Enterprise System. An Electronic
`resented as a bit map (raster image) or a vector image. (3) In the
`Data Interchange (EDI) network connection that allows the inter-
`field of image processing, a two-dimensional representation of a
`company exchange of e-mail,
`fax, electronic fund transfers,
`scene. Also called a picture.
`CAD/CAM,etc. (2) An abbreviation of Information Exchange Ser-
`vices. (3) An abbreviation of Incoming Echo Suppressor.
`image antenna A hypothetical, mirror-image antenna considered to
`be located as far below ground (ground plane) as the actual antenna
`IESG Anabbreviation of Internet Engineering Steering Group.
`is above ground.It is in the sameposition andorientation as the ac-
`IETF Anabbreviation of Internet Engineering Task Force.
`tual antenna; however, it is reversed.
`IF An abbreviation. of Intermediate Frequency.
`image frequency In heterodynereceivers, the frequency of an unde-
`sired input signal to a heterodyne receiver capable of producing the
`sameintermediate frequency(IF) as the desired input frequency.
`For example, given a local oscillator frequency of 655 kHz(/) and an
`IF frequency of 455 kHz (Af), the two input frequencies are 1110
`kHz (f+Af) and 200 kHz (f—Af), one of which is the desired fre-
`quencyandthe otheris the imagefrequency.
`imagerejection ratio In heterodynereceivers, the ratio of the inter-
`mediate frequency (IF) signal level producedby the desired input fre-
`quencyto that produced by the image frequency of equal power. The
`image rejection ratio is usually expressed in decibels (dB). Also
`called imagefrequency rejection ratio.
`imageresolution The degreeof clarity of an image due to the num-
`berof pixels per unit area. Facsimile images typically are 203 by 98
`or 203 by 198 dots per inch. Laser printers, on the other hand, may
`be 1200 by 1200 dotsper inch orbetter.
`imaginary number A number that multiplied by itself will yield a
`negative number. Imaginary numbers are represented by a numeric
`value and theletter i orj wherei orj represents V=1.(iis used pri-
`marily in the field of mathematics, while j is usually used in engi-
`neering.)
`
`IFAX Anacronymfor International facsimile (FAX) service.
`IFG An abbreviation of InterFrame Gap.
`IFM An abbreviation of Instantaneous Frequency Measurement.
`IFRB An abbreviation of International Frequency Registration
`Board. The ITU group responsible for allocating frequency bands in
`the electromagnetic spectrum.
`IFS An abbreviation ofIonospheric Forward Scatter. See ionospheric
`scatter.
`
`IGES An acronymforInitial Graphics Exchange Standard.
`IGFET An acronym forInsulated Gate Field Effect Transistor. See
`transistor.
`
`IGMP Anabbreviation of Internet Group MembershipProtocol.
`IGP Anabbreviation of Interior Gateway Protocol.
`IGRP Anabbreviation of Interior Gateway Routing Protocol. An In-
`ternetworking protocol for routers developed by Cisco SystemsInc.
`IHL An abbreviation of Internet Header Length. A 4-bit field in an
`Internet Protocol (IP) datagram (packet) that specifies the length of
`the datagram’s headerin 32-bit words.
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