EXFO FTB-5230S Optical Spectrum Analyzer for FTB 200 v2 - Manual (Page 28)

Preparing Your OSA/OCA for a Test
22 FTB-5230S/-OCA
Nulling Electrical Offsets
Nulling Electrical Offsets
The offset nulling process provides a zero-power reference measurement,
thus eliminating the effects of electronic offsets and dark current due to
detectors.
Temperature and humidity variations affect the performance of electronic
circuits and optical detectors. For this reason, EXFO recommends
performing a nulling of the electrical offsets whenever environmental
conditions change.
Nulling can be performed for all tests modes. In addition, a nulling is
performed automatically each time you start the OSA/OCA application, and
at regular intervals afterwards.
Note: You cannot perform an offset nulling in the offline version of the
application.
To perform an offset nulling:
1. From the main window, select the Acquisition tab.