A combination of signal communication facilities operated by the Army in the field and consisting of a communications center, telephone switching central and appropriate means of signal communications. [JP1]

1. In analog (usually audio) systems, reduction of the dynamic range of a signal by controlling it as a function of the inverse relationship of its instantaneous value relative to a specified reference level.
Note 1: Signal compression is usually expressed in dB.
Note 2: Instantaneous values of the input signal that are low, relative to the reference level, are… (Read More →)

In facsimile, the ratio of the level of the white signal to the level of the black signal.
Note: Signal contrast is usually expressed in dB.

Synonym modem.

1. A measure of the difference between a given signal and a reference signal.
Note: For analog signals, the signal distance is the root mean square difference between the given signal and a reference signal over a symbol period.
2. Synonym Hamming distance.

See distortion.

In an otherwise essentially flat-topped rectangular pulse, distortion characterized by a decline of the pulse top.

A multifrequency (MF) or dual-tone multifrequency (DTMF) signal timing interval during which the signal is being transmitted. For MF signals the signal duration interval begins when the last tone of the MF tone pair exceeds 90% of its steady-state value and ends when either tone of the MF tone pair falls below 90% of its respective steady-state value. For DTMF… (Read More →)

A part of a signal, distinguished by its nature, magnitude, duration, transition, or relative position.
Note: Examples of signal elements include signal transitions, significant conditions, significant instants, and binary digits (bits).

Restoration of the dynamic range of a compressed signal.