Methods for estimating data-dependent
jitter (DDJ) from measured samples of a transmitted
data signal include a first exemplary step of obtaining a plurality of measurements (e.g., time tags and event counts for selected pulse widths in the
data signal). Such measurements may be obtained at predetermined intervals within a transmitted
signal or may be obtained at randomly selected intervals, and should yield measurements for each data pulse in a repeating data pattern. An average unit interval value representative of the average
bit time of the transmitted
signal is determined. Time interval error estimates representative of the timing deviation from each
signal edge's measured value relative to its ideal value (determined in part from the calculated average unit interval value) are also determined, as well as a classification for each measured
signal edge relative to a corresponding data pulse in the repeating data pattern. DDJ
delta lines are then calculated for signal edges of each pulse width in the transmitted data pattern, from which peak-to-peak DDJ values and / or estimates of duty-cycle-
distortion (DCD) can be determined.