| 摘要 |
PURPOSE:To suppress a moire, which varies according to the change of a regenerated video signal to be FM modulated and is caused by the secondary distortion of the regenerated video signal to be FM modulated by controlling the limit level of a limiter circuit based on the detection output of a duty detection circuit. CONSTITUTION:The regenerated video signal to be FM modulated is supplied from a regenerative equalizer 2 to a limiter 3, and a pulse train corresponding to the edge of a square wave signal outputted from the limiter 3 is outputted from a pulse counter 5. The said pulse train is converted into an analog signal by an LPF 6, and outputted through a de-emphasis circuit 7. The output of the pulse counter 5 is frequency divided by 1/2 by a frequency division circuit 9, and the duty of its output signal is detected by a charge pump 10. The limit level of the limiter circuit 3 is controlled based on the output of the said charge pump 10.
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