| 摘要 |
Device for decoding and deciphering signals having undergone an MAC type coding and a ciphering by cyclic permutation with one cutoff point, that is to say by cyclic permutation of all the chrominance C and luminance Y signals starting from an abscissa a located in the chrominance signal by using a sampling frequency f0, or with two cutoff points, that is to say by independent cyclic permutation of the chrominance C and luminance Y signals starting from respective abscissae ac and ay by using a sampling frequency f0, characterised in particular in that use is made, on reception, of a sampling frequency fr which differs from f0 and is connected with the latter by the relation fr = q/p f0, p and q being integers, and in that the new address(es) of cutoff points are taken equal, for the first, to the nearest integer value of the result a' of the operation a' = p/q a, and for the second ones, to the nearest integer values of the results a'c and a'y of the operations a'c = p/q ac and a'y = p/q ay. Application to television receivers with the MAC standard. <IMAGE> |
