Noise floor automatic gain control

摘要

A noise floor automatic gain control system for radio receivers that receives a modulated signal and converts the modulated signal to a demodulated signal whose amplitude is controlled by a first gain control signal. The first gain control signal is the larger of a second automatic gain control signal that is provided by automatic gain control circuit that is activated when the demodulated signal is present, or a third automatic gain control signal that is provided by a noise floor automatic gain control circuit that is activated when the demodulated signal is not present. There is a detector circuit for detecting the presence of the demodulated signal as well as a selector circuit to select either the second automatic gain control signal or the third automatic gain control signal for the first automatic gain control signal.