| 摘要 |
PURPOSE:To shift a disturbing frequency due to mutual interference disturbance of higher harmonics to the outside of a signal band by deviating the oscillation frequency of the second local oscillating circuit from a regular oscillation frequency in a channel selecting circuit using a receiver of the frequency double conversion system. CONSTITUTION:The first mixing circuit 3 is connected to a high-frequency signal input terminal 1 through an amplifying element 2, and the second mixing circuit 7 is connected to the circuit 3 through a band-pass filter 5 and the first IF amplifying circuit 6, and an IF signal output terminal 10 is connected to the circuit 7 through the second IF amplifying circuit 9. The first local oscillating circuit 4 is connected to the first mixing circuit 3, and the second local oscillating circuit 30 is connected to the second mixing circuit 7, and fine adjustment of the local oscillation is possible in the second local oscillating circuit 30, and such fine adjustment is performed that disturbing signals due to mutual interference disturbance of higher harmonic signals of the first and the second local oscillating circuits are shifted to the outside of a required signal frequency band. |
