| 摘要 |
PURPOSE:To accelerate the response property of a gain control and at the same time eliminate the effect due to a temperature and a power supply voltage, by inserting a variable gain circuit to the transmission system of a carrier chrominance signal and controlling the gain of a variable gain circuit with the burst chrominance signal extracted out of the carrier chrominance signal. CONSTITUTION:The carrier chrominance signal supplied to an input terminal 11 of the transmission system is supplied to a variable gain circuit 13 as well as to a burst gate circuit 14a. The burst signal thus obtained is supplied to an adder circuit 17 via an AM wave detecting circuit 15a that functions as a level detecting circuit. On the other hand, the output of the circuit 13 is suppplied to an LPF16 via a burst gate circuit 14b and an AM wave detecting circuit 15b, and the output of the LPF16 is supplied to the circuit 17. Then the level detection output added at the circuit 17 is supplied to the circuit 13 as a gain control signal. |
