Explain the concept of Squelch threshold versus AGC in receivers.

• A. Squelch threshold determines when to unmute; AGC (Automatic Gain Control) adjusts gain to maintain consistent output despite signal strength changes
• B. Squelch threshold sets AGC range; AGC determines muting
• C. Squelch and AGC are the same
• D. Squelch determines audio bandwidth; AGC sets squelch threshold

Answer: (A)

Squelch threshold and AGC serve different roles in a receiver. The squelch threshold is the level that decides when the audio path should open. If the incoming signal is below this threshold, the receiver mutes to silence the hiss and noise; once a signal above the threshold arrives, the audio is heard. Automatic Gain Control continuously adjusts the receiver’s gain to keep the output level roughly constant as the signal strength changes, so strong signals don’t overload and weak signals don’t become inaudible.

So the best answer is that the squelch threshold determines when to unmute, while AGC keeps the output level steady despite fluctuations in signal strength. The other statements mix up the functions or assign roles that aren’t accurate: squelch doesn’t set the AGC range, squelch isn’t about muting anything other than audio, they aren’t the same, and AGC doesn’t determine squelch threshold.