Tektronix OI1125, Instruction Manual

Page: 56 / 88

Performance Verification
44
OI1125 E/O Transmitter Instruction Manual
Modulator Optical Output Using the Internal Laser
Check the specifications of the modulator output by doing the following
procedure.
These procedures direct you to set up the equipment to display an eye pattern
using the internal laser as the optical source. Use the eye pattern to measure the
parameters listed in Table 18 in the Test Record.
Test Overview.
1. Keep the equipment setup as shown in Figure 14 on page 36.
2. Set the BERT parameters.
3. Set initial oscilloscope settings.
4. Preview the Eye Pattern.
5. Set the oscilloscope measurement parameters.
6. Perform an oscilloscope compensation and dark level compensation.
7. Take measurements.
The following parameters are set up to measure the data for the first row in
Table 18 in the Test Record. As you progress through the table, you must change
the bit rate of the BERT and the signal conditioning mode in the oscilloscope
setup, according to the row you are completing.
BERT. Set the BERT parameters as follows:
1. Recall the 2.48832 Gb/s bit rate.
2. Set the pattern to PRBS–31.
3. Disable the adjustable duty cycle.
4. Set the mark ratio to 1/2.
5. Set the trigger to 1/32 clock.
6. Set the data amplitude to 1.5 V
p–p
.
Eye Pattern Test Matrix