A modified branch metric for decoders and equalizers is described. In one embodiment the branch metric includes determining a set of branch metric values for symbols of a received digital signal, the branch metric values indicating a correlation between symbols obtained using a reduced calculation set, the reduced calculation set being obtained by adding a common term to all of the branch metric values before determining the correlation. The branch metric may be followed by determining path metrics for paths through a decision tree using the branch metric values, and selecting a path and a corresponding symbol sequence in the received digital signal using the path metric values.