DDJ Histogram

Meas. mode:
Jitter
Waveform type:
NRZ
PAM4
Time Graphs Toolbar

The Data Dependent Jitter (DDJ) histogram displays DDJ, which is pattern-related jitter caused by the combined effects of Inter-Symbol Interference (ISI) and Duty Cycle Distortion (DCD). The graph's horizontal axis indicates negative (–) time for samples that occur earlier than expected and positive (+) time for samples that occur later than expected.

For a PAM waveform, on the graph repeatedly click the Cycle Eye button to cycle through the waveform eye on which the histogram is based. For NRZ waveforms, which only have one eye defined by two levels, there is no selection. To globally specify the PAM eye for all affected graphs:

  1. Click Measure > Configure Jitter Mode Measurements to open the dialog.
  2. In the dialog, select the Jitter Measurements tab.
  3. In the Show Graphs Based on field, select the desired eye.

The global setting effects all Time graphs except RJ/PJ and Aliased Jitter Spectrum.