Figure 53: Using Cursors To Measure Aberrations In The Eye Pattern - Tektronix WFM8200 User Manual

To Manually Measure Rise
Time Using Variable Gain
WFM8200 and WFM8300 Waveform Monitors

Figure 53: Using cursors to measure aberrations in the Eye pattern

NOTE.
Aberrations at the top or bottom line of the waveform should not exceed
10% of the signal amplitude. Automatic equalizer circuits in receivers may be
sensitive to larger aberrations.
1. Perform the initial setup for Eye measurements. (See page 105, Eye
Measurement Set Up.)
2. Press and hold the GAIN button to view the Gain pop-up menu and select
Enable for VAR Gain. Press the GAIN button again to dismiss the pop-up
menu.
3. Use the General knob to resize the waveform to 10 major divisions. Position
the top and bottom of the waveform on graticule lines.
4. Press the CURSOR button to display the measurement cursors.
5. Position the first timing cursor at the crossing of the rising edge of the Eye
waveform and the graticule line two divisions above the bottom of the
waveform. (See Figure 54.)
6. Position the second time cursor at the crossing of the rising edge of the Eye
waveform and the graticule line two divisions below the top of the waveform.
(See Figure 54.)
7. Note the 20 – 80% rise time measurement displayed in the Delta time readout.
(See Figure 54.)
Monitoring the SDI Physical Layer
107