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OTDR Series e-Manual, RevE00 Page 70 of 128
7.3 Other Parameters
•
Fiber Model : Select the type of fiber to be tested to auto populate Index of Refraction
(IoR) and Backscatter co-efficient (BS) values. To modify values, click the pencil icon
to the left of the Fiber Model field to access the Fiber Models screen. Then, tap Modify
to Add , Rename , or Remove values.
An incorrect Index of Refraction can affect measured length results.
Incorrect IoR and Backscatter values can affect Reflectance and ORL
results.
OTDR Setup: Fiber Models
These settings apply to the next measurement only.
To edit RI and BC for an already measured trace, use the
Information
button on the
Traces
tab. For more information
see, the steps in Section 8.4.1 Trace Properties .
RI (Refractive index, N): Setting for each available wavelength (also known as
group index) is used to convert time to distance. Setting proper value (1.2000-
1.8000) determines accurate distance measurement.
Refractive index can be changed for any stored trace. Enter a custom value or
select fiber type to populate corresponding values by selecting file(s) using the
Traces tab.
BC (Backscattering coefficient, BC): Represents level of backscattering in a
particular fiber. It is used for Reflectance and ORL measurement and can be
obtained from the fiber manufacturer. Backscattering coefficient can be changed
for any stored trace.