Patent ID: 7346836

Claim:
A Viterbi detector, comprising: an input terminal operable to receive a sample of a signal that represents a sequence of values; and a recovery circuit coupled to the input terminal and operable to recover the sequence from the signal by, adding only a respective predetermined first constant to each path metric for paths associated with the sequence and being to one of a plurality of E 2 PR4 states also associated with the sequence to generate a respective modified path metric for each of the paths; identifying as the surviving path the one of the paths having the smallest modified path metric; calculating a branch metric from the sample; adding the branch metric to the smallest modified path metric while identifying the surviving path to generate an updated path metric; associating the updated path metric with the one of the E 2 PR4 states, and wherein the respective predetermined first constants are selected from the following table: E 2 PR4 Paths First Constants S0 to S0 0 S0 to S1 1 S0 to S2 5 S0 to S3 10 S1 to S4 4 S1 to S5 5 S1 to S6 8 S1 to S7 13 S2 to S8 4 S2 to S9 1 S2 to S10 1 S2 to S11 2 S3 to S12 8 S3 to S13 5 S3 to S14 9 S3 to S15 10 S4 to S0 5 S4 to S1 4 S4 to S2 2 S4 to S3 5 S5 to S4 1 S5 to S5 0 S5 to S6 2 S5 to S7 5 S6 to S8 13 S6 to S9 8 S6 to S10 2 S6 to S11 1 S7 to S12 9 S7 to S13 4 S7 to S14 2 S7 to S15 1 S8 to S0 1 S8 to S1 2 S8 to S2 4 S8 to S3 9 S9 to S4 1 S9 to S5 2 S9 to S6 8 S9 to S7 13 S10 to S8 5 S10 to S9 2 S10 to S10 0 S10 to S11 1 S11 to S12 5 S11 to S13 2 S11 to S14 4 S11 to S15 5 S12 to S0 10 S12 to S1 9 S12 to S2 5 S12 to S3 8 S13 to S4 2 S13 to S5 1 S13 to S6 1 S13 to S7 4 S14 to S8 18 S14 to S9 13 S14 to S10 5 S14 to S11 4 S15 to S12 10 S15 to S13 5 S15 to S14 1 S15 to S15 0.