| 摘要 |
PURPOSE:To execute highly precise mode discrimination with a simple constitution by envelope-detecting an output in which a pass band passes through a prescribed BPF and discriminating an FM carrier frequency. CONSTITUTION:A reproduced luminance signal FM wave 5 passing through the BPF6 which sets the frequency near the synchronizing signal tip part of the luminance signal FM wave in a reference mode to the pass band is detected in an envelope detection circuit 8. At the time of the reference mode, an H level discrimination output 11 is generated from a holding circuit 10 and an L level output 11 at the time of a high band mode. Thus, highly precise mode discrimination is executed and mode switching at the time of reproducing is automatically executed.
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