Using the OTDR Module
Setting Up for OTDR Testing
7-19
7
Table 7-1.
Setting Description
When Fiber Characteristics is set to User Defined, the n and Backscatter values can be edited by
the user. When the Fiber Characteristics is set to Default, the tester uses the values defined in
the current Fiber Type.
The n value is the index of refraction. Index of refraction is used to calculate length. The default
n values defined in the fiber types are suitable for most applications. Minor differences
between the default n and a fiber's actual n usually do not make enough difference in length
to fail a fiber.
Increasing n decreases measured length.
Backscatter is the backs
catter coefficient, which indicates the amount of light the fiber reflects
back to the OTDR (using a 1 ns pulse). This value is used to calculate event reflectance for OTDR
tests.
Enter the backscatter coefficient of the fibe
r under test, if known. This value is specified by
many fiber manufacturers.
OTDR Test Settings (cont.)
-continued-
Fiber Characteristics
n
Backscatter
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