what is squelch
In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver in the absence of a sufficiently strong desired input signal. carrier squelch is unlocked and will let any signal in. Selective calling locks out all signals except ones with the correct code. In non-critical uses, selective calling can also be used to hide the presence of interfering signals such as receiver-produced intermodulation.