| 摘要 |
PURPOSE:To generate more stabilized a reproducing chrominance signal in a PAL system by outputting reference signals having the phase difference of 90 deg. with each other at every line switchingly. CONSTITUTION:The reference signals having the phase difference of 90 deg. with each other via a crystal oscillator 3 and a 90 deg. phase shifter 8 are fed to a phase comparator 5 via a changeover circuit switched at every line via a FF 10 in response to a horizontal synchronizing signal. Then the phase between the reference signal and the color burst signal by the PAL system from a burst extracting circuit 4 having a phase angle of + or -45 deg. relatively to the reference signal and outputted alternately at every line is compared by a phase comparator 5 connecting to an error voltage detection filter 12. A main frequency converter 1 or the like is controlled automatically in response to the detection error as the result of comparison and a more stable PAL system chrominance signal is generated.
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