Exfo FTB-5600 Distributed PMD Analyzer Manuel d'utilisateur télécharger pdf (Page 135)

Optimizing Measurements

Distributed PMD Analyzer 129

Use an Appropriate Spatial Smoothing Filter Value

Use an Appropriate Spatial Smoothing Filter

Value

The spatial filter for the FTB-5600 was designed to suit the filtering needs of

the cumulative PMD curve. The filter preserves sharp transition, which

often appears in cumulative PMD measurements; the sharp transition

position will not be changed by the filter.

³ An anti-causal filter has the property to remove the delay of the filter

from the filtering effect of the signal. This means that it has an effect

before the transition occurs.

In the example below, we can see the blue curve, which is the raw

data, while the black curve is a causal moving average filter and the

red one is an anti-causal moving average filter.

Note: The black and red curves are the same, but the black curve was shifted to

the left to remove the delay.

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Exfo FTB-5600 Distributed PMD Analyzer Manuel d'utilisateur Page 135