Squelch hysteresis

This is a function of the squelch control in an FM transceiver. It is a technology used on FM repeaters. Hysteresis prevents weak signals from making the squelch open and closed rapidly, which would be very annoying to other repeater users. When the signal falls below the threshold that normally causes the signal to be squelched, a delay as a result of the hysteresis keeps it open temporarily in the event that the signal recovers strength.

Squelch circuits are used to mute the audio such that the speaker is not making noise when there is no viable signal.