| 摘要 |
Video disc player is switchable between two operating modes: (1) for playback of records of color signals of one scanning standard (15,625 Hz. line frequency; 50 Hz. field frequency) encoded in a buried subcarrier format; (2) for playback of records of color signals of another scanning standard (15,734.26 Hz. line frequency; 59.94 Hz. field frequency) also encoded in a buried subcarrier format, but with a different subcarrier frequency. When operating in mode (1), recovered signals are heterodyned with output of a VCO to up-convert chrominance signal and accompanying color synchronizing component. Control of VCO is effected in accordance with output of a phase detector responding to up-converted color synchronizing component and to reference oscillations, whereby up-converted signals are stabilized against time-base errors. Switching to mode (2) effects a shift of reference oscillation frequency (or of nominal VCO output frequency) by an amount equal to frequency difference between respective subcarrier frequencies.
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