User`s guide

Interpreting RDNM Views (plots)
• DCD + ISI
• 1-Sigma
• FFT
• Bathtub
• Summary
DCD + ISI
Displays the "normalized accumulation" of all the Rising and Falling edge measurements taken during
each run. The width of this plot is normalized to one Unit Interval of the data period. Ideally, all
measurements would fall at zero on the x-axis with no jitter present. This zero value is the Ideal Unit
Interval as determined calculated by the Bit Rate that was entered. In actuality, the measurements show
a distribution of measured times. There are two histograms plotted, one for rising and one for falling
edges of the data pattern. There is often a difference in the absolute time of rising edges vs. falling
edges. An indication of DCD or Duty Cycle Distortion—a difference in the width of a '1' vs. a '0'— can be
seen when the two histograms are not over one another but have some distance between them. The pk-
pk of this plot is the DCD+ISI number in the statistics area.
© WAVECREST Corporation 2005 Section 4 - GigaView
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