Fiber Optic Cable Repair - Finding The Faults

Fiber optic fault finding

Fiber optic cable once upon a time was regarded as a technology used in only high-performance areas, however, it’s now seen in many types of environments and networks. If you know about good old copper cable, then you will soon realise a fiber optic cable is a totally different ball game.

The installation of fiber optic cable is not only different but fault-finding, or troubleshooting is a different beast altogether. Unlike copper cable, fiber optic cables are very fragile.  The delicate nature of the cable makes it prone to possible problems. We will mention the common problems that occur with fiber optic cables and how they may be repaired.


Diagnosing Fiber Cable Faults

Troubleshooting a network is not as easy as it may look. It is always good to know where to start when trying to diagnose complicated network issues. Below we have outlined some of the possible causes most common problems that can occur with a fiber optic cable.

  • Excessive bending and flexing can put physical stress on a fiber optic cable causing it to break.
  • Poor quality fiber optic cables and connectors
  • Excessive loss of signal due to a long fiber optic span.
  • "dirty" or contaminated connectors on fiber optic cables can cause extreme signal loss.
  • A faulty splice or connectors can cause a great deal of signal loss.
  • Too many connectors or splices on a fiber optic cable can lead to loss of signal.
  • Faulty fiber connection in the splice tray or connection to the patch panel

Shedding Some Light on the Situation

So, let’s begin with a quick test to see if the fiber cable is any good. Quick disclaimer! This isn’t the most scientific approach but if you don't have thousands of pounds of testing equipment this will may shed some light on the issue. (pun intended). Carefully remove the fiber optic cable connectors at both ends and shine either a laser pointer or bright flashlight in one end.

While shining a torch or laser pointer in one end, inspect the other end to see if the light is passing through the cable. If no light is visible, then the fiber optic cable is broken and must be replaced.

So I see light at the end of the cable so cable must be good, right? Err No, this can be a simple indicator of the cable not being completely damaged. You may still be able to use the fiber optic cable if the cable is not hundreds of meters long.


Signal Loss

Okay, so the light passed through the fiber what next? Now it’s time for further diagnostics to help in Identifying a fiber optic problem.

Amongst the list of typical fiber optic issues signal loss is a known perpetrator in fiber optic cable problems. Thank goodness there is a technique known as loss testing that can evaluate fiber optic signal loss.

The signal loss testing method involves hooking up a power meter to an optical light source generator. The optical light source generator will allow you to set the wavelength and dBm range to test for. The power meter will now be able to report on any signal loss once you have attached the power meter to the optical light source generator. It is advisable to the establish a baseline measurement by using a good fiber optic cable. if the questionable fiber optic cable is good, then any losses should be comparable to the baseline cable used.

  • A loss of 0.5db with a maximum of 0.75db can be seen with each connector.
  • A splice can give around a 0.1db loss.
  • Single-mode fiber optic cable can lose 0.1db every 180 metres.
  • Multimode fiber optic cable can lose around 0.1dB every 30 meters.

Patch Leads

Check that you are using the right mode of patch lead. They are colour specific.

Dirty Fiber

As previously pointed out, problems with fiber cable can occur due to contamination. Fiber optic contamination can be brought about by dust and scratches. Also epoxy on fiber optic connectors can also contribute to fiber contamination. The only way to effectively test for contaminations is by using a piece of testing equipment called a fiber optic microscope.

Fiber optic microscopes are designed primarily to inspect fiber optic cables. However, good fiber optic microscopes are not cheap they can set you back in the region of £800.


Fiber optic transceivers

Make sure that your fiber media converters or Gbic’s are compatible with the fiber cable type.


Alternative 

If you are facing problems with your fiber optic network you could try and remedy the situation yourself with our tips mentioned above. However, if you are not in possession of the correct equipment or are not confident in troubleshooting a fiber optic connection you can always call upon experts.  PSP Data Communications have possessed many years of experience in fiber optic repair and installations. We also have a dedicated team of engineers on standby for emergency fiber optic cable repairs. If you are facing fiber optic issues or require fiber optic cable installed please contact our engineers on 01270 212 211

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