Patent ID: 8340204

Claim:
Apparatus for manipulating a received signal which corresponds to a transmitted signal comprising a series of bits, the apparatus comprising a processor arranged: to process the received signal using a Viterbi algorithm to produce candidate metrics for states arranged in a trellis; to make selections from amongst the candidate metrics to provide metrics for said states; to produce an initial soft decision for a bit of said series from said candidate metrics; to produce a hard decision for said bit from a metric selection corresponding to reception of said bit; and to produce an enhanced soft decision for said bit based on (1) an absolute value of the initial soft decision and (2) the hard decision, wherein when the hard decision for said bit is a first value, the enhanced soft decision is set to the absolute value of the initial soft decision, and when the hard decision for said bit is a second value different from the first value, the enhanced soft decision is set to a negative of the absolute value of the initial soft decision, and wherein said first and second values are either 1 or 0, respectively.