| 摘要 |
PURPOSE:To normally connect the high frequency component of a video signal to the low frequency component by providing an edge detection circuit for detecting the inclination of the edge of the transmitted video signal and a carrier selection circuit for selecting a modulating carrier used for a right angle two- phase modulation. CONSTITUTION:When the transmitted video signal is transmitted, the edge inclination data of a horizontal synchronizing signal is held in the edge detection circuit 53. The held data is compared with data set to the edge detection circuit 54 in an inclination comparator 55, an output control voltage is inverted and the phase of the modulating carrier is inverted in the carrier selection circuit 23. The edge inclination data of the horizontal synchronizing signal when the modulating carrier is inverted is held to the edge detector 54. The data held in the detectors 53, 54 is compared by the inclination comparator 55 and the modulating carrier phase when the edge inclination data is steep is selected by the carrier selection circuit 23. Thereby, the phase synchronization of the low frequency component and the high frequency component of the video signal can be correctly taken.
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