Fiber optic cabling is a fast and reliable way to carry digital information over long distances, display medical imaging and aid in mechanical engineering inspection.

But even technology this reliable needs to be properly tested after installation, to check for continuity and end-to-end loss. If you are the network end user, you will also probably want to check the power, as this is the measurement that tells you whether or not your system is working properly.

Fiber Optic Testing Methods
There are five generally accepted ways to test installed cable plants. The first three use test sources and power meters, while the last two use an Optical Time-Domain Reflectometer (OTDR).

Insertion Loss Testing
This is generally how we refer to source/power meter testing. It approximates the way the cable plant is used by the actual network, so any loss will be similar to an actual loss. The three tests falling within the insertion lost test method have the same test setup, but use one, two or three cables for reference power:

* One Cable Reference – there is only one cable between the test source and the power meter. The meter effectively has no loss, so is therefore able to measure the total light emanating from the launch reference cable.
* Two Cable Reference – the launch reference cable is attached to the source, the receive reference cable is attached to the meter, and the two cables are then mated to set the reference.
* Three Cable Reference – this is used to test newer connectors, which are male-female, or plug-jack, instead of two males using a mating adapter to create a connection. Reference cables will usually be patchcords with plugs, while the cable being tested will have jacks on both ends.

OTDR Testing
ODTRs test from one end of the cable, and use the fiber’s backscatter signature to make an indirect measurement. This method of fiber optic testing maps the cabling, and shows termination quality as well as where any faults are located. It also uses advanced diagnostics to isolate any point of failure that may impede the performance of the network, and can highlight issues along the length of a channel that may ultimately affect reliability in the long term.

Delaire USA’s qualification test systems act as worst-case links for attenuation and bandwidth/dispersion. To learn how we can get you connected, visit

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