EXFO FTB-5600 Distributed PMD Analyzer - Manual (Page 129)

Optimizing Measurements
Distributed PMD Analyzer 123
Perform Two-Sided Measurements
Perform Two-Sided Measurements
To make two-sided measurements bring two advantages:
³
Nearly doubles a measurement range
³
Improves the measurement accuracy.
For example, in a case where a relative small PMD section is followed by a
high PMD section, the PMD value of the small PMD section may be difficult
to measure accurately, but it may be relatively easy to measure it precisely
from another side of fiber under test if there is no very high PMD fiber(s)
from there.
By combining two-sided measurements together, you can have a better
and clearer cumulative PMD picture with a less measurement uncertainty.
Perform Multiple Measurements
Making multiple measurements over a long time or at different times may
be helpful to reduce a fundamental PMD uncertainty if a measured PMD
from the FUT is unstable. Using a larger number of SOPs and wavelengths
may also result in a long acquisition time that would help to improve the
measurement and reduce measurement uncertainty.
Note: Averaging the measured PMD over time might be helpful to reduce a
fundamental PMD uncertainty due to a limited wavelength range.