Question

What Squelch circuit does?

(a) helps to receive signals that are useful for the system

(b) helps to make channel noise free

(c) helps to receive two or more than two signals at once

(d) helps to suppress the audio output in the absence of sufficiently strong desired signal

I have been asked this question in an international level competition.

Query is from Spectrum of Multitone Signal in section Amplitude Modulation of Analog Communications

Answer 1

The correct choice is (d) helps to suppress the audio output in the absence of sufficiently strong desired signal

The explanation is: A Squelch is a circuit which is a mean to impede, but not destroy a signal. It circuit blocks the output in the absence of sufficiently strong desired signal. It is widely used in two-way radios to suppress the annoying sounds.