Patent ID: 7526053

Claim:
An electronic circuit comprising a sequence detector for converting a sequence of digital values of a detector input signal into a sequence of symbols chosen from an alphabet of predefined symbols, each of a plurality of states of the sequence detector defined by at least one of the predefined symbols, the sequence detector comprising: a branch metric generator for generating branch metrics during multiple time periods which each progressively become the kth time period where k is a running integer, each branch metric being a measure of how much one of the digital values differs from a transition value to one of the states at the kth time period along an allowable path from one of the states at the (k−1)th time period; comparison circuitry (a) for determining best and second-best state metrics, each best or second-best state metric respectively being the best or second best of a set of state-metric computations for a particular state at the kth time period where each state-metric computation depends on the state metric for a state at the (k−1)th time period and the branch metric for a transition from that state to the particular state at the kth time period and (b) for generating best and second-best comparison results, each best or second-best comparison result indicating which state at the (k−1)th time period is the state in the state-metric computation that respectively constitutes the best or second-best state metric for a state at the kth time period; and symbol generation circuitry for utilizing the best comparison results and, as necessary, the second-best comparison results in generating a final sequence of the predefined symbols such that the final sequence approximates, as a sequence, the sequence of digital values.