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Reflective event (possible echo) – EXFO FTB-7000 OTDR for FTB-200 v2 User Manual

Page 327

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Description of Event Types

OTDR

313

Reflective Event (Possible Echo)

Reflective Event (Possible Echo)

This symbol indicates a reflective event that can be a real reflection or an
echo produced by another stronger reflection located closer to the source.

³

In the example above, the launched pulse hits the third connector, is
reflected back to the OTDR and reflected again into the fiber. It then
reaches the third connector a second time and is reflected once more
to the OTDR.

The application would therefore detect a reflective event located at
twice the distance of the third connector. Since this event is almost null
(no loss), and since its distance is a multiple of the third connector
distance, The application would interpret it as a possible echo.

³

A reflectance value is specified for reflective events (possible echo).

Reflected power
(dB)

Distance
(km)

OTDR connector

Second connector

Third connector

Reflective event (possible echo)