| 摘要 |
PURPOSE:To always attain an accurate discrimination by varying discrimination functions respectively automatically depending on the intensive strong electric field small level input state of a burst signal, an intensive electric field large level input state and a weak electric field input state. CONSTITUTION:The output of an ACC circuit 15 is fed to a killer control circuit 28 and the output of the circuit 28 controls the discriminating state of a killer detection circuit 22. Through the constitution above, in case of the intensive electric field small level input state (black/white mode) of the burst signal, the base potential of a transistor Q12 is increased to improve the discrimination accuracy, and in case of the intensive electric field large level input state (color mode) of the burst signal or a weak electric field reception state, the base potential of a TR Q12 is lowered to lower the discrimination accuracy. Since the output of a sample/hold circuit 25 and the reference level to be compared are changed in this way, the accurate discrimination is always attained.
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