Region-dependent, algorithmically directed thresholds for maximum-likelihood detection of ternary PRS channels

This paper presents mathematical derivations for a type of maximum-likelihood sequence detector (MLSD), for decoding signals equalized to the ternary partial response fundamental polynomials - duobinary (1+D) and dicode (1-D); or part of decoders for higher-order class of partial response polynomials. Region-dependent but algorithmically directed thresholds with relatively simple updates for ternary duobinary (1+D) and dicode (1-D) channel decoders are hereby presented which depend only on state metric differences. The simplicity of the threshold updates makes the new proposition very attractive for hardware implementation. Derivations for a ternary duobinary and dicode partial-response signaling (PRS) channel decoder based on the true difference metric algorithm are included.