Digital signal transmission method

Abstract

Groups of primary multi-bit digital signals arranged in digital words are spaced apart in sequence and are interleaved with related groups of secondary multi-bit digital signals, each of which is derived from, and encodes substantially the same information as, one of the primary signals. To minimize errors in processing signals, either the primary signals are delayed relative to the secondary signals, or vice versa, before they are interleaved. Cyclic redundancy check code signals are derived for each group of primary signals and each group of secondary signals and are interleaved in sequence with the primary and secondary signals. At a further stage in processing the signals, the checked code signals are analized and the related pairs of primary and secondary signals, which have been brought back into coincidence, are checked to determine whether one or both of the primary and the secondary signals of each related pair has been processed without error. If only one of the signals has been processed without error, that signal is selected for further processing. If both signals have been processed without error a predetermined one of them is selected for further processing. If neither one of them has been processed without error, the immediately preceding signal that was selected may be selected a second time. In order to incorporate all of the signals in the most convenient format, the secondary signals may comprise only the higher bit orders of the primary signals, eliminating some of the lower bit orders as containing unnecessarily detailed information. The number of bits thus omitted preferably causes a group of secondary signals plus the cyclic redundancy check code signals for that group and for the related primary group to equal the total number of bits of that primary group.