Arrangement for deciphering and decoding television pictures encoded in

Abstract

An arrangement for deciphering and decoding television pictures which were scrambled at transmission by submitting the video signals to cyclic permutations from the addresses x.sub.i of points of cut produced by a pseudo-random digital address generator. Said video signals being separate components such as analog components of the MAC type, the arrangement comprises for recreating the permuted signals two sets of random access memories (Y.sub.1, Y.sub.2) and (C.sub.1, C.sub.2, C.sub.3, C.sub.4) which are used alternately, and deciphering and decoding are realized for each component either by a first phase in which the memory is written obtained by an address jump as a function of the address of said points of cut followed by a second phase in which the memory is read sequentially, which in addition provides the time expansion of the compressed signals, or by a first phase in which the memory is written sequentially followed by a second memory read phase obtained by address jumps as a function of the address of said point of cut and which ensures in addition the time expansion of the compressed signals.