A method for sampling a data stream (22) includes receiving a segment of the data stream containing a sequence of known data, together with a source-synchronous clock signal (20), and generating a series of trial sampling clocks (60) by applying a corresponding series of different trial delays to the received clock signal The received segment of the data stream is sampled using each of the trial sampling clocks in turn to generate sampled data. The known data are compared to the sampled data to find comparison results for each of the trial sampling clocks. Responsive to the comparison results, a final delay is set, to be applied to the received clock signal so as to generate a final sampling clock for use in sampling the data stream subsequent to the segment.