Universality of blank-correction and error-detection (Corresp.)

A blank-correction error-detection decoder can be used to give any desired degree of decoding from simple error detection to essentially maximum likelihood error correction. Failsafe per-refinance is obtained if a fixed number of digits are erased before decoding with maximum failsafe protection obtained with a zero threshold detector preceeding the decoder which results in error detection only. In agreement with theory there is a nonzero threshold which maximizes the rate of transmission for any SNR. Maximum likelihood decoding is obtained by iterative decoding with successively increasing thresholds as long as errors are detected. Comparison of the performance of the decoder in a failsafe mode and a maximum likelihood mode are given.