Process for scrambling and unscrambling television pictures

Abstract From the Canadian patent

The useful signal of a sampled video line is, at least partially, spliced into two adjacent segments (AB, BC), each of these having at least two samples. The splicing point (B) between the two segments is defined in a pseudo random manner synchronous at transmission and reception. Upon transmission, at each line and in a pseudo-random manner, one of two possible scrambling schemes is selected. The first scheme involves local flipping over of the second segment, and the second scheme involves flipping over of the second segment followed by a permutation with the first segment. Upon reception, the inverse processing of that at transmission is applied in order to reintroduce intelligibility to …