Common Problems In Fiber Links - Fluke DSP-FTA420 User Manual

DSP-FTA420/30/40
Users Manual
Table 10. Common Problems in Fiber Links
Problem
No power is
measured at a source
Power loss is much
more than expected
Power loss is
somewhat more than
expected
A known length of
cable measures too
long or too short.
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Possible Causes
The optical source is defective.
The patch cord is defective.
The fibers are connected to the wrong ports on a
DSP-FTA4XX unit.
The fibers are swapped at one end of the link.
A patch cord is broken. Retest using a different set
of patch cords.
There is one or more dirty connections in the link.
Clean all fiber endfaces and retest.
The number of adapters or splices set in SETUP is
too low.
The reference power level is incorrect. Set the
reference again using the same patch cords to be
used for testing.
A patch cord or fiber segment has the wrong core
size. For example, you are using 62.5 µm patch
cords to connect to a 50 µm fiber. Or, you are
using multimode patch cords or adapters to
connect to singlemode fiber.
The index of refraction is not set correctly for the
fiber under test. Set the index of refraction to give
the correct length for a known length of the fiber.