| 摘要 |
PURPOSE:To avoid a wrong correction in case when a dropout arises for a horizontal period or longer, by adding the noise simultaneously with an addition of the 1- horizontal period preceding frequency modulated signal and the detected signal. CONSTITUTION:When the dropout is detected for the FM signal of an automatic gain control AGC amplifier 8 by a dropout detector 9, both the 1-horizontal period preceding FM signal that passed through the 1H-delaying circuit 12 and the signal produced by adding the noise from the noise generator 23 through the 1st adder 22 are sent to the 2nd adder 10 via the dropout switch 11 that works on the output of the output of the detector 9 to be added to the output of the amplifier 8. Thus the signal containing the noise is always supplied to the dropout part. In such constitution, a wrong correction can be avoided in case when a dropout continues for the 1- horizontal period or longer and synchronously with the horizontal period. |
