| 摘要 |
A video display apparatus for pictures from broadcast sources having standard or high definition, which may also display computer generated images. To display this range of sources a horizontal frequency signal generator is selectably operable at a plurality of frequencies. The generator comprises an oscillator controlled for synchronized oscillation at a plurality of horizontal frequencies. A source of synchronizing pulses is coupled to an input of a phase detector which has another input coupled to the oscillator. The phase detector generates an output signal representative of a phase difference between the inputs. A processor is coupled to the phase detector for processing the output signal and generating a control signal for controlling the oscillator. The processor gain is controlled responsive to selected ones of the plurality of frequencies.
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