| 摘要 |
PURPOSE:To eliminate a disturbing wave with no adjustment by demodulating a disturbing angular wave mixed in a reception signal wave, feeding back negatively the dem dulated signal to apply inverse modulation to the reception wave and forming the angular modulation wave into a band compression signal having a small frequency deviation thereby cancelling the modulation wave from the restored reception signal. CONSTITUTION:A local oscillation frequency of a VCO6 is multiplied with a reception signal from an input terminal 8 by a multiplier 11 to apply frequency conversion, the result is fed to a multiplier 2 via a BPF3, the inverse frequency conversion is applied by using the frequency of the VCO6 and the inputted angular modulation wave is restored by a BPF20. The modulation wave is demodulated by an FM detection circuit 5, its output controls the VCO6 to compress the band width of the modulated output wave and the inverse modulation output wave. The center frequency of the VCO6 is controlled by a center frequency control circuit 16 to apply the modulation output of the BPF3 to a subtractor 14 via a narrow band BPF18 and a level delay time adjusting circuit 13. Then the modulation wave at the same location extracted by a BPF12 is subtracted, the disturbing wave is fed to a multiplier 15 to eliminate the disturbing wave through cancellation.
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