Automatic gain control method and device

摘要

A constant output signal can be achieved by controlling a gain variable amplifier 2 based on a level of an output signal which is derived by variably amplifying a receiving signal S1 (input signal). An AGC output signal S11 is detected by a detector circuit 3. Then, a CPU 5 generates a control signal S8 based on a detected voltage signal S7. An RSSI detector portion 9 detects an RSSI signal S10 corresponding to a transmitting signal level from the receiving signal S1. The transmitting signal level is compared to a preceding transmitting signal level. The control signal from a preceding execution of the gain control is output if the present control signal is lower than the preceding control signal and the present transmitting signal level is reduced below the preceding transmitting signal level.