MIL-STD-188-110 Interoperability And Performance Standards For Data ModemsThis document establishes mandatory technical standards and design objectives \(DO\) that are necessary to ensure interoperability and to promote performance among data modulators-demodulators \(modems\) used in the voice frequency \(VF\) band of long-haul and tactical communications systems. This document also provides guidance to the designers of new data modems that incorporate characteristics not yet standardized by specifying the technical characteristics of data modems currently in the inventory. The purpose of this guidance is to ensure attainment of minimum acceptable performance and maximum interoperability between existing and future data modems with specified transmission channel conditions.

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MIL-STD-188-110C

DEFINITIONS

3.1 Terms.

Definitions of terms used in this document are specified in FED-STD-1037. For the purposes of

this standard, definitions are provided for the following terms, some of which have been

repeated, from FED-STD-1037 for the convenience of the reader.

Automatic link establishment (ALE). The capability of an HF radio station to make contact, or

initiate a circuit, between itself and another specified radio station, without operator assistance

and usually under processor control.

NOTE: ALE techniques include automatic signaling, selective calling, and automatic

handshaking. Other automatic techniques that are related to ALE are channel

scanning and selection, link quality analysis (LQA), polling, sounding, message store

and forward, address protection, and anti-spoofing.

Balanced to ground. Pertaining to electrical symmetry with respect to a common ground.

Clear-to-send (CTS) signal. The control signal generated by the transmitting modem on the CTS

connection to denote a state of readiness for transmission. The CTS signal is a response to the

request-to-send (RTS) signal from the transmitting device

Code rate. The ratio of the number of information symbols (k) to the total number of encoded

symbols (n) in a code (i.e., the ratio of k/n).

Dead time. In hopping, the portion of a hop dwell period in which no transmission occurs.

Dwell period. The maximum amount of time a transmission occurs on a particular frequency.

Galois field. An arithmetic system, containing a set of symbol elements with two operations (and

their inverses) for combining pairs of elements.

In-band diversity combining. A combining of two or more signals which uses frequencies within

the bandwidth of the information channel and carries the same information received with the

objective of providing a single resultant signal that is superior in quality to any of the

contributing signals.

Mode. An available format in a data modem supporting multi-waveform capability.

Narrowband. At HF radio frequencies (1.5 - 30 MHz) the nominal voice frequency (VF)

bandwidth allocated for single channel radio (i.e., 3 kHz).

Nominal bandwidth. The widest band of frequencies, inclusive of guard bands, assigned to a

channel.