Exfo FTB-5600 Distributed PMD Analyzer Manuel d'utilisateur télécharger pdf (Page 70)

Managing Results

64 FTB-5600

Section Event Table

The PMD section value provides the PMD of a particular section over the

link. The section's PMD value is the square root difference of the PMD

cumulative curve section's last value and the PMD cumulative curve

section's first value. The formula is:

The contribution value provides a way to evaluate the contribution of a

specific section of the cumulative PMD of a link. Since PMD adds up to the

square, the contribution is computed in squares. The percentage of

contribution values are provided in square since it is mathematically not

possible to provide a square rooted percentage. Values would simply not

add up to 100 % and be harder to interpret.

Below, you can see an example of a fiber with two sections. The first

section has a value of 5 ps and the second section, of 10 ps. This will result

in a 11.2 ps of total cumulative PMD.

PMDSection CumulPMDSectionLastValue

CumulPMDSectionFirstValue

–=

1 2 ... 65 66 67 68 69 70 71 72 73 74 75 ... 145 146

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Exfo FTB-5600 Distributed PMD Analyzer Manuel d'utilisateur Page 70