| 摘要 |
<p>PURPOSE:To simplify the constitution of the titled circuit by switching the signs of calculated results of errors in an error operating circuit alternately in every horizontal scanning frequency. CONSTITUTION:An A/D converter 11, a burst extracting circuit 14, an error operating circuit 15, and a D/A converter 16 are acted as phase comparators and an output from the D/A converter 16 is applied to a voltage control oscillator 18 as the control voltage of oscillation frequency through a loop filter 17. An output from the voltage control oscillator 18 is applied to the A/D converter 11 as a sampling clock signal. A frequency divider 40 divides the frequency of a horizontal synchronizing pulse outputted from the synchronizing separation circuit 13 into a half and an output from the frequency divider 40 is applied to a sign inverting circuit 41 to invert the sign of the output from the error operating circuit 15 on the basis of the sign of the frequency divider 40. Thus, a signal whose sign is inverted against the sign of the output from the error operating circuit 15 is outputted in every horizontal scanning frequency.</p> |
