GCI Ofix GP-1000, Руководство пользователя

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If the tested trace is just like the figure shows above, this might be
caused by several reasons like: a bad connection between the connector and
the lunching port, the optical pulse cannot be launched into the optical fiber or
a short distance broken point of the tested fiber from the initial connection and
the preset testing distance and pulse width is larger.
To fix this problem, we should:
1.
Check the connection of the connector and the launching point
2.
Reset the test parameters, decrease the preset distance and the pulse width.
If the problem still exists, we could estimate:
1.
The connector of the test fiber is broken or polluted.
2.
The launching port on the OTDR is broken or polluted.
3.
The distance of the broken point of the initial connection is too close.
Curve with Non-reflective Event
There is a common phenomenon that an obvious step is on the middle of a tested
trace, it often caused by a fiber bending, fiber knot, being pressed by something
heavy or a fuse splicing point. The step means a bigger loss of a fiber, it is also called
event point. If the direction of it is downward, it could be called non-reflection event. If
the direction is upward, we can call it reflection event.
Sometimes, the loss value could be a negative value, it does not means the loss
does not exist. It is common phenomenon called pseudo gain, it is by a connection of
two fibers with different back scatter coefficient, the scatter coefficient of the back
fiber is large than the front one's. In addition, the different refract ratio also can cause
the phenomenon. To avoid it, we could test a fiber bi-directionally.