1. A method block encoding binary data arranged in a data block of data words for later detection and correction of multiple word errors introduced by a subsequent processing step, the method comprising the steps of: deriving for each said data block of data words at least two check words for use in said error detection and correction, said check words being derived in accordance with a procedure by which said check words in combination are indicative of the location and magnitude of said introduced errors, each said check word being derived in dependence on all said data words in said data block and on all of the others of said check words derived for said data block; and association said check words with said data block.
1. A method block encoding binary data arranged in a data block of data words for later detection and correction of multiple word errors introduced by a subsequent processing step, the method comprising the steps of: deriving for each said data block of data words at least two check words for use in said error detection and correction, said check words being derived in accordance with a procedure by which said check words in combination are indicative of the location and magnitude of said introduced errors, each said check word being derived in dependence on all said data words in said data block and on all of the others of said check words derived for said data block; and association said check words with said data block. 9. A method according to claim 1, wherein said data words represent a pulse code modulated digital television signal.