Automatic sounding

In telecommunication, automatic sounding is the testing of selected channels or paths by providing a very brief beacon-like identifying broadcast that may be used by other stations to evaluate connectivity, propagation, and availability, and to identify known working channels for possible later use for communications or calling.

Note 1: Automatic soundings are primarily intended to increase the efficiency of the automatic link establishment (ALE) function, thereby increasing system throughput.

Note 2: Sounding[?] information is used for identifying the specific channel to be used for a particular ALE connectivity attempt.

Source: from Federal Standard 1037C and from MIL-STD-188