TM 11-7025-234-23
TM 11-7025-234-23
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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