DISCRIMINATING DEVICE FOR WATCHED CHANNEL

摘要

PROBLEM TO BE SOLVED: To provide a discriminating device for watched channel which is capable of discriminating watched channels by directly comparing video signals with each other even with respect to the CATV broadcasts by using synchronous compression scrambled video signals. SOLUTION: Vertical and horizontal blanking interval generators 21806 and 21807 respectively generate vertical and horizontal blanking intervals, from the vertical and horizontal synchronizing signals of the video signals projected upon the cathode-ray tube of a television set. An analog switch 21809 extracts the signals in the generated vertical and horizontal blanking intervals from synchronous compression scrambled video signals generated by means of an image receiving circuit in a watched channel discriminating device. A waveform restoring section 21810 restores the signals extracted by means of the switch 21809 to the state, before the signals have been synchronous compression scrambled. Another analog switch 21811 generates a video signal which becomes a basis at the discriminating of a watched channel by replacing the signals in the generated vertical and horizontal blanking intervals with the signals restored by means of the restoring section 21810.