1. Operation in which transmission occurs in one and only one preassigned direction. Synonym one-way operation.
Note: Duplex operation may be achieved by simplex operation of two or more simplex circuits or channels.
2. Operating method in which transmission is made possible alternately in each direction of a telecommunication channel, for example by means of manual control.
Note: In general,… (Read More →)

A communications protocol that is purely one-way, and where acknowledgments are not part of any application protocol. Error control is either not provided, or is accomplished via forward error correction. [T1.80
0. 08-1995]

To represent certain features of the behavior of a physical or abstract system by the behavior of another system.
Note 1: For example, delay lines may be used to simulate propagation delay and phase shift caused by an actual transmission line.
Note 2: A simulator may imitate only a few of the operations and functions of the unit it simulates.

1. Abbreviation for signal-plus-noise-plus-distortion to noise-plus-distortion ratio.
1. The ratio of (a) total received power, i.e., the received signal-plus-noise-plus-distortion power to (b) the received noise-plus-distortion power.
2. The ratio of (a) the recovered audio power, i.e., the original modulating audio signal plus noise plus distortion powers from a modulated radio frequency carrier to (b) the residual audio power, i.e., noise-plus-distortion… (Read More →)

An undesired self-sustained audio oscillation in a circuit.
Note: Singing is usually caused by positive feedback, excessive gain, or unbalance of a hybrid termination, or by some combination of these.

The difference in power levels between the singing point and the operating gain of a system or component.

The threshold point at which additional gain in the system will cause self-oscillation.

The term "Singing Return Loss" denotes the frequency weighted measure of return loss at the edges of the voice band, where singing (instability) problems are most likely to occur.

Comprising or containing only one security class [CESG].

A device which can only be used to process information of a single security class at a time [CESG]