PURPOSE:To prevent a picture at the time of compression-switching from moving right and left by adding a pulse equivalent to that remaining in a scramble and descramble action to a front porch part synchronous with a video signal. CONSTITUTION:A scramble encoder 2 adds a pulse signal (6dB compression pulse) to a signal from a TV demodulator 1 at an imcompressible time. The time delay of an output signal from a circuit which separate a synchronizing signal from a video signal in a TV set coincides with the time of compression delay in a compressed time. Thus, 6dB compression pulse signal width is set to deal with the signal width which remains in the video signal in the TV set. The video signal is adjusted to the signal of other channel and transmitted to the trunk line of a CATV.
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