Patent ID: 8140949

Claim:
An ACS unit of a Viterbi decoder, comprising: a state calculator for calculating a first sum of a first state metric of a first candidate source state and a first branch metric of a first transition from the first candidate source state to a target state, calculating a second sum of a second state metric of a second candidate source state and a second branch metric of a second transition from the second candidate source state to the target state, providing a selection signal indicating a selected source state which is the first candidate source state or the second candidate source state corresponding to the lesser one of the first sum and the second sum, and then providing the lesser sum as a target state metric of the target state; and a BER calculator coupled to the state calculator for providing a third sum of a BER of the selected source state and a BEC of the transition from the selected source state to the target state as a BER of the target state.