| 摘要 |
PURPOSE:To simply and correctly detect a non-standard signal by comparing phase error signals between a vertical blanking period and a video period in a television receiver. CONSTITUTION:The oscillating output signal of a VCXO105 is compared in phase with a burst signal inputted from an input terminal 102 in a phase comparison circuit 103 for every burst period and a phase detection signal is outputted. Only the direct current component of this phase detection signal is taken out, the signal is converted to the phase error signal to be the control signal of the VCX 105. When the special reproduced signal of a VDP or the like is inputted, the phase of the burst signal is discontinuous in the vertical blanking period, thereafter, the oscillating frequency of the VCX 105 is changed according to the phase error signal, operated synchronously with the burst signal again after 10-20 horizontal scanning period, so that an APC circuit is stabilized during the video period.
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