| 摘要 |
PURPOSE:To increase the S/N of the composite color signal as well as reduce the cross-color, by recording the amplitude of the recording composite color signal so as to approximate to the amplitude of the carrier chrominance signal and then to be set to the original state when reproduced. CONSTITUTION:Composite color signal Es obtained from input terminal 11 and through the band filter is applied to amplifier 12 to be amplified with amplification degree A>>1. After this, the output signal is applied to output terminal 13 and nonlinear circuit 14. The gain of amplifier 12 is controlled by the control signal sent from the negative feedback circuit consisting of circuit 14, amplitude detector 15 and time constant circuit 16 each. Thus the output of amplifier 12 is set to the fixed amplitude level. At the same time, circuit 14 is used as the diode limiter comprising diodes D1 and D2, and the amplitude of signal Es is recorded so as to approximate to the amplitude of the carrier chrominance signal and then set to the original state when reproduced. As a result, the S/N can be increased for the composite color signal. |
