Tektronix OI1125, Instruction Manual, Page: 67 / 88

Performance Verification
OI1125 E/O Transmitter Instruction Manual
55
Compensate the Oscilloscope
Perform a Dark Level Compensation on the
Oscilloscope, as described on page 48.
NOTE . Repeat the dark level compensation routine between every table in these
tests. The extinction ratio measurements rely on accurate dark level compensa-
tions. Perform the compensation more frequently if the ER measurements are
failing.
The equipment is now set up for recording measurements in Table 19:
1. Press the Clear Data button, and then the Run/Stop button on the oscillo-
scope to begin a measurement. You may need to adjust the horizontal
position slightly to center the eye pattern around the center mask boundary.
2. Verify that the eye pattern does not violate the mask boundaries.
3. Record the measurement data (Figure 17) in the first row of Table 19. Check
that the data meets the limits in Table 17.
4. Adjust the tunable laser and BERT to the remaining wavelengths and power
levels in the 1.5 V rows in Table 19. Repeat steps 1 through 3 to complete
the 1.5 V rows in Table 19.
NOTE . You must connect an attenuator on the BERT output to take the 0.25 V
measurements in Tables 19 through 21. Therefore, it is easier to take the 1.5 V
measurements first, and then connect the attenuator. Next, complete the 0.25 V
rows in Table 21 and work backward to Table 19.
5. Recall the 9.953 Gb/s data rate on the BERT.
6. Set the filter field on the oscilloscope to OC-192. See steps 1 through 3 in
the Oscilloscope Setup on page 45.
7. Repeat steps 1 through 4 for Table 20.
8. Recall the 12.500 Gb/s data rate on the BERT.
9. Set the filter field on the oscilloscope to None. See steps 1 through 3 in the
Oscilloscope Setup on page 45.
10. Repeat steps 1 through 4 for Table 21.
11. Disconnect the cable from the BERT output, and connect the 2X attenuator
to the BERT output. Connect the cable to the attenuator.
12. Set the BERT amplitude to 0.5 V.
Take Measurements