Patent ID: 7558343

Claim:
A method of reducing the number of path metric calculations in a trellis of a Viterbi equalizer, the method comprising the steps of: receiving a sequence of symbols by said Viterbi equalizer, performing a preliminary decision of at least one of the previous symbols in the sequence of symbols within said Viterbi equalizer; identifying a subset of destination states which are excluded from path metric calculations within said Viterbi equalizer and determining for each of the remaining destination states a survivor path by comparing all path metrics to this state; determining the most likely of the survivor paths within said Viterbi equalizer and determining the value of the oldest symbol in the symbol sequence from this survivor path; generating the trellis within said Viterbi equalizer by calculating path metrics only for states in which the oldest symbol is identical to the determined value; and decoding said sequence of symbols with said Viterbi equalizer using the trellis.