| 摘要 |
PURPOSE:To obtain the titled color demodulator with which the output voltage of a demodulator has no fluctuation with each 1H, by providing the low pass filters to the lines which connect a changeover switch to the 1st and 2nd color demodulators respectively. CONSTITUTION:A color demodulator is provided with a limiter amplifier 1, an 1H delay line 2, a B-Y demodulator 3, an R-Y demodulator 4, a changeover switch 5 having a limiter amplifying function, and LPF6, 7 and 8 which are connected to the amplifier 1 and the output of the switch 5. These LPFs contain active LPFs in order to improve their characteristics. In addition, an active LPF is provided at an input stage of a changeover switch of a present signal. This is due to the fact that the effect is improved by approximating the waveform of an input terminal as close as to the sine wave of an 1H delaying signal. Thus the value of 1H level difference is set at about 30mV in terms of chroma output with addition of three active LPFs. |
