| 摘要 |
PURPOSE:To cancel a buzzing component in a detection sound signal by providing an adjusting circuit and an arithmetic circuit, adjusting the phase and the amplitude of automatic frequency (AFC) control signal, thereafter supplying to the arithmetic circuit and adding in a reversed polarity to a detecting sound signal from a sound detecting circuit or subtracting in the same phase. CONSTITUTION:The output signal of an LPF 12 is supplied to a phase adjusting device 13, herein, the phase is set to the buzzing component in the detecting sound signal of the sound detecting circuit 18, further, the buzzing component is set to the amplitude in a level adjusting device 14, and thereafter, the output signal is supplied to the arithmetic circuit 15. The detecting sound signal of the sound detecting circuit 18 has the phase adjusted through a phase adjusting device 16 and is supplied to the arithmetic circuit 15. In the arithmetic circuit 15, when an input AFC signal is adjusted so as to be the same phase as the bussing component in the FM detecting sound signal, the subtraction is performed and when it is adjusted so as to be the reversed phase to the buzzing component, the addition is performed. As a result of this, the sound signal in which the buzzing component is cancelled is taken out to an output terminal from arithmetic circuit 15.
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