GLOSSARY

TM 11-7025-234-23

GLOSSARY

ANALOG. When used in telecommunications, means a continuous electrical signal that

varies in frequency or amplitude in relation to a digital input. Since digital

signals cannot be transmitted over long distances, the modem is used to convert

digital signals into analog signals which can be transmitted.

ASCII. American Standard Code for Information Interchange. A standard used for

transmission of data between computer systems and remote terminals. A coded

character set consisting of seven bit characters (eight with parity check).

ASYNCHRONOUS. Data communications which is not time related. Uses stop and start

bits instead of time pulses to organize data for transmission.

BAUD . A unit of measure for data transmission.

Indicates the rate of changes in

signal over a given period of time.

DIGITAL. When used in telecommunications, means a nominally discontinuous signal

that changes in frequency, amplitude and polarity.

Miniature rocker switch used to select configurations of circuit boards.

DIPSWITCH.

DEDICATED LINES.

Lines assiqned to one user only.

EQUALIZER. A passive device designed to compensate for an undesired amplitude -

frequency and/or phase frequency characteristic of a system or component.

FALLBACK CAPABILITY. Ability to change from 9600 to 7200, 4800 or 2400 bps when

conditions are not good for the fastest mode.

FULL DUPLEX.

Communications mode which allows transmission and reception at the

same time.

HALF DUPLEX. Communications mode which allows transmission and reception but not

at the same time.

MODEM. Modulator-Demodulator.

A device which converts digital data to analog form

so it can be transmitted. Also receives analog form and converts it to digital

data.

QUADRATURE. Modulation of two carrier components 90° apart in phase by separate

modulating functions.

TRAINING. The method of communication synchronization necessary between

transmitter and receiver functions of two modems to lock in the flow before data

transmission is possible.

SYNCHRONOUS. Data communications which operate at one baud rate and does not need

stop and start bits for transmission.

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