EXFO FTB -5240S/5240BP Optical Spectrum Analyzer - Manual (Page 21)

Preparing Your OSA for a Test
OSA 15
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 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.