Patent ID: 6034735
Filing Date: 2000-03-07
Classification: H04N

Abstract:
A clock generator for generating a sampling clock signal in a digital video processing apparatus which digitizes an analog composite video signal in accordance with the sampling clock signal, extracts color and luminance signals from the digitized composite video signal, and produces color difference signals by using the color signal in accordance with a chrominance subcarrier signal in demodulator, the clock generator comprising:burst phase error detector for outputting a color burst phase error signal based on the color difference signals;oscillator for generating the sampling clock signal in accordance with the color burst phase error signal; anddivider for dividing the sampling clock so as to produce the chrominance subcarrier signal and for adjusting the phase of the chrominance subcarrier signal in accordance with the color burst phase error signal, wherein the divider comprises:a ratio counter for dividing the clock signal to produce the chrominance subcarrier signal, wherein the ratio counter comprises:a first signal generator for producing a first signal indicative of ""1"" at intervals of 33 clocks of the sampling clock signal;an adder for adding the chrominance subcarrier signal, the color burst phase error signal, a signal indicative of ""543"", and the signal indicative of ""1""; anda register for holding the output signal of the adder depending on the sampling clock signal and outputting the chrominance subcarrier signal; andphase shift signal generator for generating a phase shift signal having a phase of the chrominance subcarrier signal shifted by 90 degrees, and wherein the demodulator comprises:a first multiplier for multiplying the color signal by the chrominance subcarrier signal;a first low-pass filter, connected to the output of the first multiplier, for producing a red color difference signal, which is supplied to the burst phase error detector;a second multiplier for multiplying the color signal by the phase shift signal; anda second low-pass filter, connected to the output of the second multiplier, for producing a blue color difference signal, which is supplied to the burst phase error detector.