| 摘要 |
PURPOSE:To receive not only SECAM but also other color TV signals, by holding the output of a phase dicriminator with at least either of the 1st and 2nd gate pulse strigns and by outputting a switching signal through the comparison between the held voltage and reference voltage. CONSTITUTION:Phase discriminator 17 discriminates the output phase of a FM detector with a line sequential signal varying in polarity in every 1H interval. Then, the output of discriminator 17 is held 21 with at least either the 1st gate pulse string which coincides with the interval when the 1st and 2nd carrier signals should be inserted or the 2nd gate pulse string which coincides with a line sequential discrimination signal interval to be inserted into a vertical flyback interval, and comparator circuit 22 compares the held voltage with a reference voltage so as to output a switching signal. As a result, not only SECAM color TV signals with only either one of two kind of line sequential switching signals but other color TV signals can be received by the same discriminator circuit. |
