EXFO FTB-3930 MultiTest - Manual (Page 36)

Measuring Optical Return Loss
30 FTB-3930
Performing ORL Reference and Setting ORL Zero Value
The ORL measurement procedure is outlined below:
Performing ORL Reference and Setting ORL
Zero Value
The ORL zero measurement eliminates the effects of backreflection on the
link before the component under test, so your unit displays only the
backreflection of this component.
You should set a new ORL zero:

when you change the measurement patchcord (the one connected to
the DUT, not the reference patchcord)

when you remove a connection between the unit and mandrel
To set the ORL zero value (all wavelengths at once):
1. From the main window, select the ORL Meter tab.
2. Press ORL Zero.
Set
ORL zero
Measure
ORL
Save
results
Perform
ORL reference
Set up thresholds
(see page 16)
Null offsets
(see page 22)
Select
wavelength