| 摘要 |
PURPOSE:To eliminate the level fluctuation of a carrier chrominance signal for the SECAM based on the level difference of two kinds of burst signals, by controlling variably the level of the carrier chrominance signal in response to the level of the extracted burst signal. CONSTITUTION:The carrier chrominance signal from an amplifier 5 is applied to a burst gate circuit 11 and one burst signal BR is extracted. Further, an output through a detecting circuit 13 is applied to a comparator 14 and the burst signal BB of a small level is extracted. Further, the signal is pulsed at an MV15 and applied to an AND circuit 24. Further, the output of the amplifier 5 is applied for detection to an envelope detecting circuit 16. A gate output (i) of a burst gate circuit 19 is applied to a sample-and-hold circuit 17 and the detected output of the burst signal BR is sampled and held. This sample hold output (j) is applied to a high speed ACC amplifier 6, the amplified gain is controlled in response to the level of the burst signal BR and the level of the chrominance carrier signal is controlled variably. |
