
A decoder including first and second decoding stages for selecting a codeword near to a given N-tuple r which is a sequence of N real values r.sub.i representing signals. The first stage includes substages associated respectively with sections r.sub.j of N-tuple r, each substage for evaluating distances between multiple sets of possible partial codewords and the section r.sub.j and for selecting a survivor from each of the multiple sets based on the distances. The second stage includes n-1 subst...











