| 摘要 |
PURPOSE:To prevent the lock-out phenomenon of an AGC circuit, by supplying the output of a noise detecting circuit to a subtraction or addition processing circuit through a waveform shaping circuit. CONSTITUTION:Noise detecting circuit 4 which is connected to the output terminal of detecting circuit 1 in DC and detects the white noise in the direction where the noise exceeds the zero carrier wave level is constituted by a level comparator and a signal processing circuit having a filter function or a delay function to obtain the approximate envelope response of the output of this level comparator at least. The white noise is erased by subjecting the white noise, which is detected by noise detecting circuit 4, and the output of detecting circuit 1 to the subtraction processing, and meanwhile, the black noise is erased by subjecting them to the addition processing. |
