Exfo FTB-5600 Distributed PMD Analyzer Bedienungsanleitung PDF herunterladen (Seite 134)

Optimizing Measurements

128 FTB-5600

Use an Appropriate OTDR Pulse Length

A recommended pulse length of 100 ns should be used for most

acquisitions. However, when a depolarization effect for this pulse may be

too big because of short beating lengths from FUTs (that are often observed

in the field fibers), a short pulse length, for example, 50 ns, may be used to

reduce the depolarization effect and improve SNR so as to ensure an

acquired signal level that is larger than a coherent noise level, but it will

result in a reduced measurable range.

On the other hand, if the FUT has a small depolarization, use a long pulse

length, for example, 275 ns, for the acquisition may be helpful to increase

the measurable range or reduce the acquisition time.

Below you can see an example of a depolarization on a fiber:

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Exfo FTB-5600 Distributed PMD Analyzer Bedienungsanleitung Seite 134