| 摘要 |
PURPOSE:To discriminate assuredly a prescribed one of plural synchronizing signals by correcting the reference level of a comparator in response to the frequency change of the synchronizing signal if generated by the variation of the tape speed. CONSTITUTION:For a synchronizing separator of an ACC circuit part, a horizontal synchronizing signal SH separated from the luminance signal Y is supplied to a compaator 14 via a reproduction speed detecting circuit 31. The reference level of the comparator 14 is controlled by the reproduction speed detecting signal S23 of the circuit 31. The outut signal S5 of a wave detecting circuit 13 has fluctuation within a certain level range when burst signals BR and BB arrives at a filter circuit 12 in a normal reproduction mode. Therefore the reference level of the comparator 14 is set at a level within said range by the signal S23. The output S5 has 2% up/down fluctuation in a triple speed and reverse reproduction modes respectively. As a result, the signal S23 corresponding to the tape speed sets the reference level of the comparator 14 with 2% up/down fluctuation. |
