Abstract: A CATV scrambling and descrambling method in which the horizontal and vertical synchronizing signals of a composite television video signal are compressed in level, and a timing signal indicating the time positions of the horizontal and vertical synchronizing signal and which is superposed on a television audio signal is transmitted. On the transmitting side, the timing signal is superposed on an audio signal while moving the timing signal at random prior to transmission, an indication of the time position is indicated with a data signal, and this data signal is superposed on the audio signal at a different time position than the timing signal. On the receiving side, the data signal is decoded to detect the time position of the timing signal, and only the horizontal and vertical synchronizing signals of the video signal are level corrected to reproduce the video signal.