What is the purpose of a squelch circuit in a receiver?

The purpose of a squelch circuit in a receiver is to cut off output when there is no signal. This function serves to eliminate unwanted noise and hum that can occur when the receiver is not picking up a signal. By doing so, the squelch circuit helps to improve the overall listening experience by ensuring that the receiver only outputs audio when a valid signal is present. This is particularly important in communication systems, as it allows operators to focus on relevant transmissions without being distracted by background noise.

When the squelch threshold is set appropriately, it will remain quiet during periods of no transmission and activate when a transmission is received that meets or exceeds the threshold level. This feature is essential for efficient communication, particularly in environments with many potential interference sources.

The other choices, while related to the functioning of a radio receiver, do not correctly describe the function of a squelch circuit. Boosting signal strength, enhancing audio output clarity, and modulating frequencies pertain to other aspects of audio processing and reception, rather than the specific function of controlling noise in the absence of a signal.