What is the primary function of a squelch circuit in a radio?

The primary function of a squelch circuit in a radio is to filter out unwanted noise. Squelch circuits serve to suppress background noise when no intended signal is being received, enabling the radio to remain silent in the absence of clear transmissions. This enhances the listening experience by reducing distractions and allowing users to hear only relevant communications.

When the received signal strength exceeds a certain threshold, the squelch automatically 'opens,' allowing the signal to be heard. This capability is particularly useful in environments with a lot of static or interference, as it prevents the operator from having to continuously listen to noise when no conversation is taking place.

The other options do not accurately describe the squelch circuit's purpose. Amplification of signals is a different function typically handled by the radio’s audio amplifier. Converting digital signals to analog is relevant in contexts of signal processing but unrelated to squelching functions. Encoding transmitted data pertains to a different area of radio operation entirely, focusing instead on how information is prepared for transmission rather than how it is managed during reception.