| 摘要 |
PURPOSE:To improve a speech quality, by generating a signal having amplitude and phase which erase a beat sound from a sound signal obtained by demodulating FM and PM signals, from an AM component of the FM and PM signals, and erasing the beat sound only when not busy. CONSTITUTION:When a beat is generated in an output of a discriminating circuit 4 by interference from other office, an AM component is fetched by a detecting circuit 6 simultaneously, and a beat sound is detected. This beat sound is adjusted by an adjusting circuit 7 so that its phase is opposite to the beat generated in the output of the discriminating circuit 4 and the amplitude becomes equal to the latter, and the beat sound is erased by a subtracting circuit 9. A busy detecting circuit 10 detects busy when a sound output level of the discriminating circuit 4 exceeds a specified value, and cuts off an output of the adjusting circuit 7, therefore, no output of the detecting circuit 6 gives disturbance to a call voice. |
