| 摘要 |
PURPOSE:To effectively utilize channels by stopping any unwanted channel output at the modulator provided with modulation units for plural channels. CONSTITUTION:A video signal inputted from a video signal source is processed by a video signal processing part 31 and sent to a video modulation part 34. At this video modulation part 34, a wave to be modulated from a variable frequency oscillation part 35 is modulated by the video signal from the video signal processing part 31 and outputted through a high frequency switch part 37, which is controlled by a microcomputer 6, to a high frequency amplifier 38. The microcomputer 6 is provided with a function for selectively setting either a normal channel or a dummy channel to each modulation unit 4 based on the operation of a channel setting switch and when the dummy channel is selected by the operation of the channel setting switch, a modulated output is cut off by turning off the high frequency switch part 37. As a result, the output of an unwanted carrier to the relevant modulation unit 4 can be cut off.
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