EXFO FTB-5600 Distributed PMD Analyzer - Manual (Page 126)

Acquisition Data
120 FTB-5600
The FTB-5600 takes care of this issue: it automatically computes all of the
sampling steps required between the span provided. Only the value at the
end of the link (the PMD scale), and the minimum value desired (the
residual PMD) need to be set.
Note: The PMD sampling steps overlap by 3.
In the example below, the chosen scale is 8 ps and the residual PMD of
60 fs. We can see each scales with their saturation level and how they are
used to compute the overall PMD curve.
Scale (ps) Step (GHz) Residual PMD (ps) Saturation (ps)
8 12.5 1.6 19.4
2.67 37.5 0.533 6.5
0.889 112 0.178 2.15
0.296 337 0.06 0.7
Saturation at 6.5 ps
Saturation at 2.15 ps
Saturation at 0.7 ps