Most premises cables are short enough that the primary cause of loss is the loss is the connectors. Since they are generally field-terminated, connectors will be the focus of testing. Each connector should have three tests:
1) Visual inspection with a microscope to verify polishing if field polished and to ensure no dust or other contamination are present.
2) Loss, called insertion loss, measured by a light source and power meter.
3) Polarization that is the fibres are arranged so one end of each fibre link is connected to a transmitter and the other end to a receiver.
Fibre testing is much simpler than copper or wireless testing, as the installation needs only testing for end-to-end loss with a simple fibre test set. Unlike copper, installation of connections is unlikely to affect the bandwidth of the fibre. Only the loss and fibre cables have no crosstalk problems, so simple loss testing is all that is required. Most premises networks are too short to be tested by OTDRs so OTDR testing is not required by any premises standard. Testing therefore is simple, fast and inexpensive. Standards call for insertion loss testing using a light source and power meter with reference launch and receive cables which match the fibre size and connector type of the cable plant being tested as shown in the diagram below.
Since most premises cables use multimode fibre, one must be careful to control the test source launch conditions to get trustworthy test results.
When the networking or transmission equipment is installed, an optical power meter can be used to test the transmitter and receive power in the link to determine if the system is within the manufacturer’s specifications.
With the small size of glass optical fibres, dirt is a major concern. Dust particles are large compared to the core of fibres and may scratch connectors if not removed by cleaning. Patch panels have mating adapters that can become contaminated by dust if left open to the air. Test equipment has fibre-bulkhead outputs that need periodic cleaning, since they may have hundreds of insertions of test cables. Always keep dust caps on connectors, bulkhead splices, patch panels or anything else that is going to have a connection made with it. Not only will it prevent additional dust build-up, but it will prevent contamination from being touched or damaged from dropping. Always clean connectors before insertion, whether testing or connecting patch cords and equipment.
Most consultants and standards specify that light source / power meter testing (LS/PM) is the only reliable method of accurate loss measurement on a fibre optic link. Unfortunately not many companies know how to do it correctly and properly certify your systems.
Datatel use high quality reference grade test leads in conjunction with Bi-Directional duplex testers. We adhere to the Australian standard for testing, and are constantly upgrading our procedures and training to ensure we are testing to the highest industry standards.
We have invested heavily in our test equipment, enabling us to certify your new or existing optic fibre cabling system using our fleet of Fluke cable testers. We provide you certified test results, giving you the confidence that your network operates at the speed it was designed for.