| 摘要 |
PURPOSE:To eliminate variation in AFT among channels and to securely perform AFT operation over all channel by switching the level of an AFT signal by the reception bands of a tuner and adding it to a tuning voltage. CONSTITUTION:A tuning control signal TU (PWM signal) is generated from an AFT signal which is obtained from a television intermediate frequency signal by AFT detection 12 and the tuning voltage is obtained according to the tuning control signal TU and a tuning control circuit which adds the AFT signal to the tuning voltage to perform tuning control varies the sum quantity of the AFT signal according to a reception band. Thus, the variance in AFT among the channels is eliminated and the AFT operation is securely performed over all the channels. Consequently, even a channel of a different band can be placed in the best reception state at all times.
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