a method is provided . in this method , a clock signal and an input signal are received , where the input signal is a manchester encoded signal . a unit interval number is incremented for each ui received upon receipt of a valid ui . the ui number is compared to a plurality of threshold values after the each increment of the ui number , where each threshold value is associated with at least one of a plurality of sum values . for each threshold value , once exceeded by the ui number , its sum value is incremented for each cycle of the clock signal , and a plurality of window lengths are calculated , where each window is calculated based at least in part on at least one of the sum values at predetermined values of the ui number .