As network speeds increase, so does the importance of the light loss on your key fibre links. Scroll down to read more about the different ways of testing fibre.
| Inspection | Light Loss | Basic Certification | OTDR |
| Fluke Networks FiberInspector Pro & Mini | Fluke Networks OptiFiber | ||
| Fluke Networks FiberViewer | Fluke Networks DTX Compact OTDR |
NEW!! Download the Fluke Networks Fiber Cabling Test & Troubleshooting Handbook here.
Cleaning
Cleaning your fibre end-faces can reduce your loss by more than 1dB. Using canned air or shirt sleeves are not appropriate for the dust and oil particles that need removing. An appropriate kit will contain alcohol based cleaning wipes which clean the ends and dry in the air to leave a clean surface for the connection.
Inspection
For inspection there are two types of fibre inspection microscopes; optical and video.
Optical - small and less expensive, usually involves a fibre viewer with an eye piece at one end and a slot to insert the fibre at the other. Such as Fluke Networks FiberViewer.
Video – these solutions have a small camera that you insert into the end of the fibre and a video screen which displays the results. These are usually deemed safer, as there is no risk the eye if you plug a live fibre into the unit. Such as Fluke Networks FiberInspector.
Light Loss testing
The first step in verifying your fibre cabling is a simple light loss measurement using a light source and power meter test set. Once a baseline reference has been set, with the source on one end of the fibre and the meter on the other the total amount of light loss can be measured. The standards specify a budget for the amount of light a splice, join and 100mtrs of fibre can lose, so from these measurements it is possible to calculate whether the reading you have is a Pass or Fail.
Light Loss testing does need to light to be able to get to the end of the cable to work, therefore it cannot identify breaks. There is also an issue with spotting a poor link in the middle of a good cable. If the total amount of light lost is inside the budget figure then a poor connection can be hidden inside a Pass result.
Basic Certification
Certification of the light loss of a link against the industry standards is known as Basic or Tier 1 Certification. The standards state budgetary figures for light loss for joins, splices and attenuation (loss inside the fibre). The standard is based on the fact that you know how many joins are in the link you wish to test and you use a reference measurement (usually a known / trusted patch lead).
There is also an Extended or Tier 2 Certification test, which states that the performance of every splice and patch should be measured individually and links can be failed if one of these events is out of specification, even if the budget loss for the whole link is OK. To perform these tests you need an OTDR unit.
OTDR
Optical Time Division Reflectometer is a device that launches a very bright light into the fibre and looks for reflections. The signature of the reflections indicate the nature of the join / splice and the amount of light reflected shows the quality of the event. Due to the amount of light needed to make this technology work, it is necessary to use launch leads (very long patch leads up to 100mtrs) to give the light time to settle down before it hits the first real event in the cable.
OTDR units can measure the distance to a break, therefore tend to be very popular when solving issues.
