| 摘要 |
PURPOSE:To switch image receiving circuits automatically according to a reception system by providing the 1st phase detecting means for controlling the switching phase of a PAL switch circuit and the 2nd phase detecting means for controlling the operation on the basis of the phase detection output of said means. CONSTITUTION:For reception on a PAL system, respective system changeover switches 20, 21, and 22 are changed over to PAL system side contacts P automatically according to the output of a phase detector 5 to turn off a color phase adjusting device 17, and demodulated color difference signal outputs B-Y, R-Y, and G-Y are led out of demodulators 13 and 14 and a matrix circuit 15. In this state, if a signal on an NTSC system is received, a burst gate circuit 8 separates a burst signal on an axis B-Y, which is inverted by a PAL switch circuit 7 and then supplied to a phase detector 5 to perform phase detection regarding a subcarrier. At this time, the output of the phase detector 5 goes down to ''0'' and the system changeover switches 20, 21, and 22 are all changed over to NTSC system side contacts N automatically. |
