EXFO OTDR 2 - Manual (Page 99)

Analyzing the Results Manually
OTDR 91
Getting Section Loss and Attenuation
Although this method works fairly well for splice loss, it is clearly not
appropriate for reflective events (definitely not a “straight-line” event). A-B
LSA loss is mainly used to rapidly compute loss over a given length of a
fiber section.
Note: A-B LSA event loss measurements should be used on fiber sections only.
Measuring events will not yield meaningful results.
To get section loss and attenuation:
1. From the main window, select the Measure tab.
2. Tap the Section button. Markers A and B appear on the graph.
3. Place markers A and B at any two points on the trace. For more
information, see Using Markers on page 83.
4. Zoom in on the trace and fine-tune the marker positioning if necessary.
For more information, see Using Zoom Controls on page 109.
Note: There should not be any event between markers A and B when performing
a measurement.
A-B Least-square
approximation
loss
A-B Least-square
approximation
attenuation