Error correction in coded messages

Error correction in convolutionally coded messages, using a plurality of information digit streams and a single parity digital stream with each information digit being included as a component in the defining summation for exactly two parity digits spaced apart by a certain number of time intervals (a time interval being defined to include a digit from each stream), the time interval spacing between the two parity digits being the same for each information digit in a given stream but different for each stream, the spacing being longer than the design correctable burst length but shorter than twice the design correctable burst length for all but at most one of the information digit streams.