The fiber length in fiber optic cables is always longer than the cable length primarily because the optical fibers inside the cable are not laid straight, they are helically twisted or loosely spaced ...
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Cables for OTDR testing should be sufficiently long for the launch cable to extend beyond the OTDR dead zone under test conditions and the receive cable should be long enough to be easily seen by
Excess fiber length inside a cable affects OTDR distance readings because the OTDR measures the length of the fiber itself, not just the cable length.
One of the questions I get asked about regarding optical cable measurements is: “Why don''t my OTDR and jacket length markings agree?” The answer depends on the type of cable being
For every fiber optic cable plant, you generally need to test for continuity and polarity, end-to-end insertion loss, verify installation with an OTDR and then troubleshoot any problems on every fiber in
Since fiber optic cable has about 1% excess fiber, the actual cable length is less than the fiber by that amount. The OTDR makes its measurements on the fiber, not the cable, so one must estimate the
So the answer to the question of how long the distance between the fiber and the jacket should be is: it depends on the design of the fiber, how the fiber was printed during manufacture, and
Is there a specific formula to calculate this, for example if the OTDR show 5000 meters of fiber, how long is the actual cable? What you''re looking for is called the helix factor and it''s usually a few percent.
There are two main reasons: Optical gain is seen when backscatter level increases between the first and second fiber sections because of refractive index differences; and fiber core diameter differences
The first and most common assumption is that for central tube designs – where all the fibers are pulled in together – the fiber length and cable jacket length are best if they are the same length (i.e., there is
For this first question, it is important to understand that the longer the fiber is, the more the fiber loss is, and so the more dynamic range is needed to measure the end of the fiber. Dynamic range is