CHROMINANCE SIGNAL PROCESSING DEVICE

摘要

PURPOSE:To obtain always an accurate axis of demodulation and constitute a comb line filter into a semiconductor and make it small-sized by using information of a burst part of the R-Y axis as a control voltage of a voltage control oscillator (VCO) which operates an A/D converter and a demodulator. CONSTITUTION:A reproduced signal obtained from a reproducing head 30 passes an amplifier 31, an LPF32, and an automatic signal gain adjuster (ACC)33 to become a low-band conversion chrominance signal having a certain level and is converted to a digital signal by an A/D converter 34. This digital signal is demodulated to a B-Y signal and an R-Y signal by a demodulator 35, and they pass comb line filters 36 and 37 respectively to eliminate crosstalk and are applied to the modulator 38. The R-Y signal of the output of the comb line filter 37 is subjected to D/A conversion and is applied to a burst gate 42, and a burst signal obtained there is applied to a VCO45 through a switch 44 and an LPF46. The output of this VCO45 is used as a reference clock of the demodulator 35 to keep always the axis of demodulation accurate.