| 摘要 |
<p>PURPOSE:To reduce a beat interference with a color secondary carrier by eliminating the relation of a sampling frequency and a color secondary carrier frequency and modulating a sampling clock. CONSTITUTION:A primary oscillator 3 generates the sampling clock 4, a modula tor 5 modulates the clock 4 in phase by the output of an oscillator 6 and feeds a sampling clock 4' to an A/D converter 2. Since the frequency of the color secondary carrier of a complex color television signal 1 is not synchronized with a frequency of the sampling clock 4, a beat interference is generated. Since said clock 4' changes time to time, the beat interference changes corre spondingly, attracts no attention by a visual characteristic and can be equivalent ly reduced. The range of said phase modulation is about 2pi/100 at the frequency of a modulated wave.</p> |
