EXFO MAX-700 - Manual (Page 191)

Analyzing the Results Manually
MAX-700 179
Getting Optical Return Loss (ORL)
Getting Optical Return Loss (ORL)
Note: You must use a singlemode OTDR for ORL calculations.
The ORL calculation will provide the following information:

the ORL between markers A and B

the total ORL is calculated either between the span start and the span
end, or on the total fiber span, depending on the option you have
selected in the Setup window.
Optical return loss (ORL) refers to the total effect of multiple reflections
and scattering events within a fiber-optic system.
Note: If you are testing in Real time, the reflectance value you will get is not
necessarily accurate.
To get the ORL value:
1. From the main window, select the Measure tab.
2. In the Results section, press ORL. Markers A and B appear on the
graph.
3. Position markers A and B to delimit the area for which you want to
know the ORL value.