| 摘要 |
PURPOSE:To reduce the deterioration of picture quality due to drop-out further more by providing the titled device with a correlation detecting means to generate an detected output corresponding to the vertical correlation between the 1st and 2nd video signals and a means to change a detecting level in accordance with the detected output of the correlation detecting means. CONSTITUTION:The envelope of an obtained reproduced FM signal is applied to an input terminal of a comparator CP1 to compare the voltage of the FM signal with a detection reference level applied to the other input terminal and detect the drop-out. Since the output voltage of a correlation detector 3 is set up to zero at the complete vertical correlation and negative polarity voltage is increased at the less vertical correlation, the degree of the change of the detection level of drop-out is adjusted by the strength of the vertical correlation. The output voltage is applied to a voltage follower OP3 through a resistor R13 to convert its impedance and voltage obtained by dividing the difference between the output voltage of voltage follower OP3 and a power supply voltage by resistors R14, R15 is used as the detection reference level of the comparator CP1. |
