Syllabus Sections:-

Automatic Gain Control

4p.1 Understand the derivation and use of an AGC voltage.

Recall that automatic gain control circuits can also be used to drive S meters.

The automatic gain control or AGC is a voltage controlled part of the receiver with the voltage coming from the detector stage. The level of the voltage is directly related to the strength of the signal.

The voltage is used to control the gain of the receiver and so enable the receiver to handle a wide range of signal strengths with little or no change in output audio level.

This same voltage can be used to drive a Signal strength meter or "S" meter.


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