| 摘要 |
PURPOSE:To receive simply both NTSC and PAL color broadcasts by dividing an inputted reference subcarrier into a wave having a phase difference of 90 deg., synthesizing with an optional rate, dividing the synthesized wave into two and using each selectively. CONSTITUTION:The reference subcarrier to an input terminal 6 is divided into the 1st reference subcarrier and the 2nd reference subcarrier having a phase difference of nearly 90 deg. by the 1st phase shifter 7 and the 2nd phase shifter 8, they are outputted respectively from the 1st output terminal 9 and the 2nd output terminal 11 and inputted to a hue controller 14. The 2nd carrier is synthesized and the ratio of synthesis is changed by a control voltage of a phase control terminal 13. The synthesized carrier is divided into the 3rd and 4th reference subcarriers having a phase difference of nearly 90 deg. by the 3rd and 4th phase shifters 15, 16 and inputted to a PAL switch 18. When the input signal is a PAL signal, the phase of a reference carrier for R-Y axis demodulation is inverted by 180 deg. at each horizontal scanning period and the signal is outputted to the 2nd output terminal 20. |
