Tektronix ATECTekRanger User Manual page 48

Setups
Scattering Coefficient
The scattering coefficient represents the amount of backscatter
reflected by a particular fiber. The scattering coefficient is not
required, but if you know the coefficient of your test fiber, you can
use it to maximize reflectance-measurement accuracy. The scattering
coefficient is a characteristic of the fiber under test and, similar to
the refractive index, can vary from fiber to fiber.
The scattering coefficient is usually available from the fiber
manufacturer. If you do not know the scattering coefficient, however,
use the factory-default values.
NOTE. The scattering coefficient applies only to reflectance
measurements and has no effect on any other types of measurements.
When comparing a reflectance measurement to any previous
reflectance measurements made on the same event, be sure to use the
same scattering coefficient that was used for the previous measure-
ment.
Refer to Table 1–1 on page 1–11 for factory default settings.
For 1550-nm dispersion-shifted fiber, use a scattering coefficient of
-78.2.
If you do not know the scattering coefficient of a particular fiber, but
the fiber includes a reflection with a known reflectance, adjust the
scattering coefficient until the reflectance value for the event is
correct.
When you change the scattering coefficient, reflectance values are
not automatically recalculated. To recalculate reflectance values,
retest the fiber.
The scattering coefficient is user settable in all modes.
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TFS3031 TekRanger/TekRanger 2 User Manual