User`s guide

If you have selected to have a Diagnostic FFT performed, the PJ frequency components are
determined by taking the variance of timing measurements from the histogram of each UI. The
variance is the square of the standard deviation of the histogram at each UI. If any "holes" in the
variance record exists, they are interpolated by either a cubic or linear fit. The plot of variance
versus UI (1 – sigma view) is the autocorrelation of the periodic jitter. Refer to the "High Frequency
Modulation" getting started guide for further information about this concept.
Lastly, the random and deterministic jitter is separated using the TailFit algorithm. The DJ value
reported is the greater value between the mean of the tailfits and the mean of the extreme
histograms. For more information on TailFit, see TailFit Theory. Also you can refer to the Histogram
Tool Overview section of help.
© WAVECREST Corporation 2005 Section 4 - GigaView
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