US 4,636,851 A · Signal coding for secure transmission

Abstract

A multiplexed analogue component (MAC) television signal is encrypted for transmission and reception by authorized recipients only by dividing the signal into blocks and reordering the blocks prior to transmission. The signal within each block remains in its original order. Preferably, the signal representing one line of video is split into blocks which are reordered within the line time to cause translation or rotation of analogue components. Alternatively a group of lines may be processed as a group to cause reordering of the analogue components between lines. The preferred arrangement does not split the blocks of analogue signals already present in the MAC signal. The receiver is arranged to receive information regarding the encryption technique with the television signal and to reorder the blocks constituting the received signal whereby to reconstruct the original signal.

Claims5

Dependent claims

A method of processing a signal representing a line of a television picture, comprising the steps of

(a) generating a sampled signal;
(b) dividing the sampled signal into blocks of information;
(c) loading said blocks of information in a first order into a plurality of stores whose total capacity is sufficient to store information representing one line;
and
(d) reading out said blocks of information in said stores in a second order different from the first order with the information within one of said blocks when read out being in the same order as when written into a store;
thereby to provide an encrypted signal;
(e) said sampled signal generation comprising the step of processing an input signal to provide multiplexed signals representing digital information, sampled analog chrominance information, and sampled analog luminance information for the complete line, said sample signal division being arranged to divide one of said multiplexed signals into a plurality of portions altering the position in the line of at least one of said portions.

4 more elements

Dependencies are inferred from the claim text.

Signal coding for secure transmission

Life of this patent

Signal coding for secure transmission

Life of this patent

Abstract

Claims5