Two-way radios use this threshold control to silence the constant background static that occurs on an empty channel. When an incoming transmission exceeds the set voltage threshold, the circuit opens and allows audio to pass to the speaker. If the threshold is set too high, the operator will miss weak but legitimate incoming transmissions.
Heard on the job
Turn your squelch down until you hear static, then roll it back up just until the noise stops.
Related terms
Gating
The process of controlling or blocking a signal based on a specific threshold or timing condition.
Spectral gating
A digital signal processing method that reduces background noise by muting specific frequency bands.
Hot microphone
A microphone that is actively transmitting or recording without the user actively pressing a button.