CHROMINANCE SIGNAL PROCESSING METHOD

摘要

PURPOSE:To omit an LPF or a BPF having sudden cut-off characteristics by eliminating the undesired side band wave component produced in a demodulation mode to a baseband through a comb-line filter of the base band and a holding circuit in case a carrier color signal of low band is converted into a chrominance signal of the base band or into a prescribed carrier chrominance signal. CONSTITUTION:A carrier chrominance signal CL of low band conversion which is recorded and reproduced by a color-under system is applied to a balanced modulators B5 and R6. The outputs of modulators B5 and R6 are converted into base band chrominance signals B-Y and R-Y through comb-line filters B9 and R10 and then sample holding circuits B11 and R12 respectively. The signal of a subcarrier frequency fL of a low band conversion carrier chrominance signal CL is applied to both modulators B5 and R6 respectively with a 90 deg. phase difference produced by a phase shifter 7. There a color demodulator 8 is formed with both modulators B5 and R6, the shifter 7 and the conversion carrier fL.