| 摘要 |
PURPOSE:To reduce the interference due to cross modulation caused between the video and sound signals by adding the difference signal between two frequency divided/multiplexed signals added together in the same and adverse phases and undergone the pulse width modulation and one of both multiplexed signal after the prescribed band limitation. CONSTITUTION:A wide band color video signal is converted into an FM signal by an FM modulator 1; while a PCM sound signal is converted into an EFM signal by an EFM encoder 2. The video FM signals are supplied to the pulse width modulators 5 and 8 in the same phase. While the sound EFM signals are supplied as they are to the modulator 5 and to the modulator 8 with the signal phase inverted by a polarity inverter 9 respectively. The output of the modulator 5 is supplied to an adder 12 via a delay equalizer 10 and an LPF 11 as well as to a subtractor 13. At the same time, the output of the modulator 8 is supplied to the subtractor 13 and the difference signal is supplied to the adder 12 via a BPF 14 and a level controller 15. The output of the adder 12 is outputted gain through a limiter 16 as a frequency multiplexed rectangular wave signal. Thus it is possible to reduce the interference due to the cross modulation caused between the video and sound signals.
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