| 摘要 |
PURPOSE:To reproduce faithfully a chrominance signal even in case a color correlation in the vertical direction is absent by opening one end of a trap circuit is used and grounding both the other end of the trap circuit and the output end of 1h delay line comprising the comb-shaped filter circuit, in case the trap circuit is used. CONSTITUTION:When a changeover switch 7 is switched to the side of a contact (b), a trap circuit 6 of 3.58MHz will not operate because a grounding terminal of said circuit 6 is connected to a positive power source with the aid of a resistance 9. In such a case since a diode 8 is turned off, the output of 1h delay line 1 is added to an original NTSC complex video signal, and the former and latter are transmitted to processing circuits 10 and 11 as a luminance signal and a chrominance signal, respectively. A circuit constituted of A, B and C operates as a comb-shaped filter circuit. Then, when the changeover switch 7 is set to the side of a contact (a), the grounding terminal of the trap circuit 6 is grounded. At the same time the diode 8 is turned on, and the circuit constituted of A, B and C operates as a trap circuit of 3.58MHz.
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