1) Simple AGC:- Simple AGC is a system by means of which overall gain of a radio receiver is varied, automatically with the changing strength of the receiver signal to keep the output substantially constant. Hence the receiver gain is automatically reduced as the input signal becomes more & more strong There is a reduction in gain for weak signals. It is used in domestic radio receiver.
2) Delayed AGC:- As shown in the diagram, AGC biased is not applied until the input signal strength reaches the predetermined level of point A After this level, the point A AGC bias is applied just like simple AGC but more strongly. There is no reduction in gain for weak signals. The problem of reducing the receiver gain for weak signal is avoided .the delayed AGC is not used in low cost radio receiver. It is used in high quality receiver like communication receiver.