A system and method for calculating and applying a metric that is calculated over a binary interval that corresponds in length to a preamble. The value of the metric reflects the likelihood that the interval is the preamble. A lower value for the metric suggests that the interval is more likely to be the preamble. In an embodiment, the metric is calculated beginning at an initial location in the bitstream, and then recalculated beginning at each of several successive locations in the bitstream. This results in a set of calculated metrics. The start of the preamble is considered likely to be the initial location of the interval that corresponds to the metric having the lowest value.