Frekvensfoervandlingssystem foer video

摘要

The object of the present invention is to provide various scramble systems and equipments for embodying the scramble systems for omitting unqualified viewers in a pay TV system such as CATV. One of the scramble system according to the present invention is characterized in that a horizontal blanking interval and a video signal interval in at least one specified horizontal scanning line are shifted with respect to the time axis thereof to be transmitted in combination with other horizontal scanning lines in which no shifting operation is conducted. Another scramble system is characterized in that a horizontal line in which a horizontal blanking interval is deleted and the remained video signal interval is shifted within the time interval equal to the thus deleted horizontal blanking interval in addition to the above system. A further scramble system apart from these systems is characterized in that a pedestal part of a specified horizontal scanning line within a vertical blanking interval is compressed with respect to the time axis thereof, whereas a pedestal part of another desired horizontal scanning line within the same field is expanded for a time interval corresponding to the thus compressed pedestal part. And, a still further scramble system is characterized in that an audio signal as well as the video signal is also scrambled.