| 摘要 |
PURPOSE:To prevent noise from generation on the picture of cathode-ray tube by constituting the titled receiver so that its video reproduction system is made non-active by the logical output of a frequency band changeover voltage and a channel-selection voltage in case reproducing a sound from a received sound broadcasting that does not accompanied by a video included in a specified frequency band. CONSTITUTION:When the channel selection voltage VT supplied to a terminal 10t goes to lower than VTC, the discrimination output VD from a terminal 10d comes to be '1' equally to the power source voltage VCC. Inversely, when the voltage VT is higher than the VTC, the said output VD actually comes to be zero equal to the grounding potential. However, in case either of the band changeover voltages VL and VH is '1' even if the voltage VT is below the VTC, the discrimination output VD comes to be zero. When the discrimination output VD in '1' from a sound- broadcasting discriminating circuit 10 is supplied to a video-color signal circuit 5, the circuit 5 is made go into a non-active state, and the picture of the cathode-ray tube 6 comes to be black out, and hence no noise appears. The signal path covering from a tuner 1 to a sound circuit 8 reproduces the sound from the received sound broadcasting without any influence of the circuit 10. As a result, the noise is prevented from appearing on the picture of the cathode-ray tube 6.
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