| 摘要 |
PURPOSE:To prevent the deterioration of sound quality, by eliminating distortion in as suppressing circuit, in suppressing multi-path noise together with pulsive noise. CONSTITUTION:When no multi-path noise is present and only pulse noise is present, this pulsive noise is detected at a high-pass filter 3, it is amplified at a noise amplifier 4, a monostable multi-vibrator 5 is triggered with the rise of this output, a gate circuit 8 is interrupted while the set time of this multivibrator 5, and no OUT output to a multiplex demodulation circuit is produced. Next, when a multi-path noise is produced, the gain of a noise amplifier 4 is immediately lowered with the operation of an AGC circuit 6, and the monostable multivibrator 5 and the gate circuit 8 are inoperative. An AGC circuit 11 requires time by the AGC operation and a noise amplifier 9 produces an output while this time, a monostable multivibrator 10 is triggered and a gate circuit 12 is in off-state. |
