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Performance Verification
9. In the Bandwidth field, select 12.50 GHz from the drop-down menu.
10. Recall the 12.500 Gb/s bit rate on the BERT and repeat steps 1 through 6 for
the 12.500 Gb/s bit rate.
11. Keep the test setup connected for the next test.
Modulator Polarity
The modulator polarity test uses an eye pattern for a pass/fail test. The eye
pattern crossing point is adjusted with the BERT, and the crossing point shift
direction is observed on the oscilloscope.
Test Overview.
1. Keep the equipment setup as shown in Figure 14 on page 36.
2. Set the BERT parameters.
3. Set the oscilloscope measurement parameters.
4. Preview the eye pattern.
5. Take measurements.
BERT. Set the BERT parameters as follows:
1. Recall the 9.953280 GB/s bit rate.
2. Set the pattern to PRBS–31.
3. Disable the adjustable duty cycle.
4. Turn off the Data Crossing Point Adjust.
5. Set the mark ratio to 1/2.
6. Set the trigger output to 1/32 clock.
7. Turn the data output on, and set the data amplitude to 1.5 V
.
p–p
Oscilloscope. Set the TDS8000 settings as follows:
NOTE. Due to differences in oscilloscope firmware, your setup steps may differ
slightly.
1. From the toolbar, select Setup→Vertical.
2. Click the Optical>> button.
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OI1125 E/O Transmitter Instruction Manual
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