SCRAMBLING AND DESCRAMBLING SYSTEM OF CHARGED TELEVISION

摘要

PURPOSE:To prevent picture reception from being performed without inserting any coin and only a sound from beong listened to by removing a synchronism signal from a video signal on a scrambling side. CONSTITUTION:The scrambling side extracts the synchronizm signal from the video signal and erased it at a synchronism signal erasure part 1. The extracted synchronism signal component is superposed on an audio signal by a mixer 2. This audio signal containing the superposed synchronism signal and the video signal having the synchronism signal removed are modulated by a television modulator 3 to generate an RF signal, which is sent to a community receiving line. Therefore, the picture reception is not performed unless the signal is demodulated on a descrambling side.