Operation Manual

Chapter 7: Use the OTDR
The SmartLoop Test
185
Note
When you save SmartLoop results, the tester saves
the results in two records, one for each fiber in
the link.
Bi-Directional SmartLoop Tests
OTDR tests from both ends of a fiber can give different results
because some properties of fiber and fiber components can cause
differences in the loss measurements in each direction.
For example, the loss of an event is the difference between the
backscatter levels before and after the event. If a segment after a
connector or splice has a higher backscatter value than the
segment before, the tester shows different values of loss for the
connector or splice from the two directions.
For splices, which have very little loss, the difference in the
backscatter of the two fibers can cause an apparent gain in power
across the splice in one direction.
For this and other reasons, bi-directional averages of connector
and splice loss in both directions are more accurate than
measurements from one direction.
The bi-directional SmartLoop test gives you bi-directional OTDR
results for both fibers in a link. The tester also automatically
calculates averages of the two results and includes the averaged
values in the test record.
How to Do a Bi-Directional SmartLoop Test
1 On the home screen, tap the test setup panel, make sure the
correct SmartLoop test is selected on the CHANGE TEST screen,
then tap EDIT.
2 On the TEST SETUP screen, in the Bi-Directional panel, tap the
control to make it show On, then tap SAVE.
(continued)