Sequence detector using viterbi algorithm with soft output error correction

摘要

A sequence detector (1400-w) operating generally according to the Viterbi algorithm contains a branch metric generator (1402-w), comparison circuitry (1403-w), and symbol generation circuitry (1404, 1405, and 1406) for converting digital values of a detector input signal into a sequence of predefined symbols chosen from an alphabet of predefined symbols. The comparison circuitry provides soft output signals for correcting errors. The soft output signals include best and second-best state metrics (p_k,w(i) and p2_k,w(i)) and corresponding best and second-best comparison results (D_k,w(i) and D2_k,w(i)). The symbol generation circuitry typically utilizes the best comparison results to generate a preliminary sequence of the predefined symbols, checks for error in the preliminary sequence, and utilizes the second-best comparison results in correcting any such error in the preliminary sequence so as to convert it into a final sequence of the predefined symbols.