Agilent Technologies 86038A User Manual page 264

Troubleshooting and Upgrades
If the SWEPT data looks incorrect
N O TE
264
may be faulty. Some ODAs have very low PDL. Test a device with known polar-
ization dependent loss, greater than 0.2 dB PDL, to isolate a polarization scan-
ner failure. If the PDL still reads extremely low, the polarization scanner is faulty
and the test set will need to be replaced.
3 If the data still looks incorrect,
looks incorrect" on page
1. Check the Modulator Bias
Connect a patch fiber and run the Modulator Bias measurement. Without
the proper value, optimal power may not be reaching the PNA receiver.
Connect a mouse and click on Measure->Optimize Optical Modulator Bias
(F8) and then run your measurement again. After the Modulator Bias
routine finishes, open the Real-Time Port Monitor by clicking on System-
>Real Time Port Monitor (F12). If the Gain/Loss values are still low, there
may be a problem with the Test Set. With a short patch cord, Gain/Loss
should be approximately -16 dB.
2. Check the Trigger Line
Ensure that the trigger line is connected between the TLS Trigger Out and
the Test Set TLS Trigger Input.
If the Group Delay curve is steep, there is a possibility that the change in
phase between two points is too large. This condition will result in a phase
wrap. Refer to "If the Group Delay measurement shows a sudden large
offset" on page 267.
Troubleshooting Incorrect Data
refer to "If the Stepped GD and Gain/Loss data
263.
Agilent 86038A Optical Dispersion Analyzer, Third Edition