| 摘要 |
PURPOSE:To stably and accurately detect a phase error voltage by matching the terminal voltage of an APC filter with a horizontal synchronizing signal voltage by the timing of a single pulse. CONSTITUTION:The phase difference between a burst signal (b) obtained by gating a chroma signal 7 of 3.58MHz and a reference fsc from an XO (crystal oscillator) 1 is taken out of the terminal 4a of the APC filter by an APC detection circuit 3 as an error voltage (d) at every one-H i.e. at the timings of respective burst gate pulses. This filter terminal voltage is forcibly matched with the reference voltage at the timing of a signal pulse. Since a single switching circuit 5 operates even during a V-cycle, a 9H-segment when no bursts exist, the terminal 4a returns to the reference voltage at the timing when a single pulse is present.
|
