| 摘要 |
A circuit for automatic gain control of an electrical signal in response to an AGC signal, said electrical signal having a selected centre frequency and said electrical signal being applied to a signal processor, said circuit comprising: a first attenuator (45) coupled to said signal processor (17) having a first adjustable resonant frequency which is below said centre frequency; a second attenuator (50) coupled to said signal processor (17) having a second adjustable resonant frequency which is above said centre frequency; a first control circuit (56) coupled to said first and second attenuators (45, 50) for adjusting the frequencies of said first and second resonant frequencies to be symmetrical about said centre frequency; and a second control circuit (54,55) coupled to said first and second attenuators (45, 50) for adjusting the spacing between said first and second resonant frequencies in response to said AGC signal. <IMAGE> |
