Partial correction of transmission errors in d.p.c.m. without recourse to error correction coding

A method for partially correcting transmission errors in a 1st-order d.p.c.m. system, without recourse to channel coding, is described. A simple detection algorithm based on the statistical properties of a sequence of differences between adjacent samples of a modified decoded sequence is used to identify the erroneous samples. Three different correcting algorithms are described. Substantial improvements in the decoded waveform are achieved, and, for a Markov input process, an error rate of 0.04% in the first and second most significant digits, an improvement in s.n.r. of 7dB is achieved.