EXFO FTB-7000 OTDR Series for FTB-500 - Manual (Page 211)

Analyzing the Results Manually
OTDR 197
Getting Optical Return Loss (ORL)
Getting Optical Return Loss (ORL)
Note: You must use a singlemode OTDR for ORL calculations. The ORL
measurement may not be displayed if the acquisition was obtained with
older OTDR modules.
The ORL calculation will provide the following information:
³
the ORL between markers A and B
³
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.
To get the ORL value:
1. From the main window, go to the Graph tab and press the Measure
button.
2. In the Measurements 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.
ORL between
markers A and B
Total return loss
of the span