EXFO IQS-1600 High-Speed Power Meter for IQS-500/600 - Manual (Page 48)

Preparing Your High Speed Power Meter for a Test
40 IQS-1600
Nulling Offsets
To perform an offset nulling on all channels (two- and
four-channel power meters):
1. Install the protective caps over all of the detector ports.
2. Under Nulling, click the All Channels button.
Offset nulling values are applied to the channel until a new nulling is
performed. A message prompts you to ensure that the detector caps
are properly installed.
3. Click OK to perform the offset nulling, or Cancel to exit.
A red message appears beneath the power value of the channel for
which you are performing a nulling.