1. A method of calculating a branch metric for a chunk of soft scrambled code bits received from a transmitter, the method comprising; generating a chunk of branch metric computation bits comprising bits that correspond to transition bits of a possible chunk of transition bits that could have been generated by a state transition of a convolutional encoder of the transmitter; scrambling the bits of said chunk of branch metric computation bits; and calculating a branch metric for the received chunk of scrambled code bits as a function of said scrambled bits of the chunk of branch metric computation bits and said soft scrambled code bits of the received chunk of soft scrambled code bits, the soft bits of the received chunk of soft scrambled code bits corresponding to bits that were generated by a state transition of the convolutional encoder in the transmitter and then subsequently scrambled by the transmitter prior to transmission by the transmitter, said branch metric being indicative of the probability that the received chunk of scrambled code bits was originally generated by said convolutional encoder as the chunk of transition bits corresponding to said generated chunk of branch metric computation bits.