1. A method comprising the steps of receiving a sequence of signal points that represent a sequence of transmitted symbols, each symbol of said sequence of transmitted symbols being selected in accordance with a convolutional code from a constellation comprising a plurality of subsets, each subset comprising a plurality of symbols, and decoding the received sequence of signal points to provide a sequence of received symbols which represent an estimate of the sequence of transmitted symbols, where the decoding step includes a step of calculating a transition metric for each subset of said constellation for each one of the received signal points, where at least one of this plurality of transition metrics for a respective subset is calculated as a function of an error metric of a different subset.