a method of scrambling a television signal is provided in which , during a horizontal blanking interval and during a vertical blanking interval , a video signal is compressed and a key signal containing information concerning the compression is superimposed on an audio signal in the horizontal blanking period . the method is characterized by superimposing a pseudo - key signal on an audio signal in the vertical blanking interval , making the key signal contain information concerning the position of a vertical blanking interval , and fixing a video signal in a predetermined number of horizontal scanning periods before a vertical synchronizing signal portion in the vertical blanking interval at a constant level while eliminating color bursts in a predetermined number of horizontal scanning periods before and after the vertical synchronizing signal portion in the vertical blanking interval . in this way , unauthorized users are prohibited from receiving the signal , and unauthorized access is made difficult .