Monitoring the S
DI Physical Layer
Taking Eye Measurements
After y ou have configured the instrument for Eye measurements, you can have the instrument perform automatic eye
measurements (Option PHY only) or you can use the cursors to perform manual waveform measurements. The following
procedures explain how to conduct both measurement types.
NOTE. Eye measurements are not available with Options 3G or JIT.
Setup for Eye Measurements
1. Configure yo
ur instrument to monitor
the SDI physical layer. (See page 57,
Configuring Physical Layer Settings
(Options E
YE and PHY).)
2. Connect a s
erial video-signal to your
instrument using a 75Ω cable of
two m eters or less in length. Use
high-qua
lity, low-loss coaxial cable, such
as Belden8281.
3. Press the EYE button.
4. Press the GAIN button to display the
gain menu, select VAR Gain, and turn
the GENE
RAL knob until the vertical
gain is x1.00.
Manual Eye Measurements
The following procedures describe how to take manual measurements of the Eye w aveform. If Option PHY is installed, the
instrument can also take automatic eye measurements. (See page 68, Automatic Eye Measurements.)
NOTE. If you have Option PHY and you use the measurement cursors to manually measure the eye waveform, you
may get a different result than that shown in the automatic eye measurements readout. This is because the automatic
amplitude measurement uses histograms in order to be minimally affected by overshoot, ringing, and noise on the signal.
Similarly, the automatic risetime and falltime measurements use histograms to find the centers of the distributions of
20% and 80% crossings. The difference between manual and automatic measurements is usually insignificant for clean,
symmetrical signals.
Usage Notes
Use the LINE SWEEP button to change the sweep of the Eye display.
Waveform Monitors Quick Start User Manual 65
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