| 摘要 |
PROBLEM TO BE SOLVED: To accurately remove a inter modulation disturbance by providing an analog signal processing means, inter-modulation disturbance detecting means and an automatic gain control circuit for controlling the gain of the analog signal processing means. SOLUTION: The outputs of an RF amplifier means 2 and 3 are fed back with a level detector 20, the reverse input side of a differential stage 18 and an integrator 19, and automatic gain control is realized. An IF signal is supplied to the inter modulation disturbance detecting means 11-14 with an amplitude modulator 8. A band-pass filter 14 placed in the rear of the amplitude detector 13 is connected to the first terminal of a correlator 12. A signal generator 10 generating a gain modulating signal is connected to the second input terminal of the correlator 12. The correlator 12 supplies an output signal to a voltage source 17. A gain control signal from the voltage source 17 and the gain modulating signal from the signal generator 10 are supplied to a signal multiplier 11. The signal multiplier 11 supplies a sum signal, included in a signal product in its own output signal, to the non inversion input side of the differential stage 18.
|
