What is the function of automatic gain control (AGC) in a receiver?

Automatic Gain Control (AGC) is a circuit designed to keep the audio output of your receiver at a relatively constant volume, regardless of how strong or weak the incoming radio signal is. It achieves this by automatically adjusting the receiver's internal amplification based on the incoming signal. When you tune into a very strong signal, the AGC lowers the gain to prevent the audio from being deafeningly loud or distorted. Conversely, if a signal fades or you tune to a weaker station, the AGC increases the gain so you can still hear the audio clearly. Distractors often confuse AGC with other receiver functions. For example, removing high-amplitude short-duration noise pulses is the job of a Noise Blanker (NB), not the AGC. AGC is solely focused on smoothing out macroscopic variations in signal strength to maintain a steady volume.