An insertion loss test is also known as an attenuation or jumper test. You cannot perform an insertion loss test on more than 1 cable at a time.
The optical source is also known as a light source or power source. An insertion lost testing kit costs $500-3000, depending on how much functionality you want in your testing kit. Test kits typically come with 2 jumper cables, which you need to complete the test. If they don’t, purchase 2 fiber optic jumper cables separately. You also need 2 fiber optic patch panels. A patch panel is basically an array of different ports for patching 2 cables together without splicing them (like a breadboard). A single patch panel costs $10-250, depending on how many ports you need. For an insertion loss test, you only need 2 ports on each panel.
For a plastic fiber optic cable, use 650-850 nm. For a multimode index cable (that isn’t yellow and has 2 ports at each end), use 850-1300 nm. Set your meters to 1310-1625 nm for single-mode fiber cables (which have 2 ports on each end and is almost always yellow). Every testing kit has different menu controls and buttons. Some machines use dials, while others use digital screens to change wavelength settings and send test signals. Consult your testing kit’s instruction manual to determine how your specific testing kit functions. For fiber optic cables, the wavelength is always measured in nanometers (nm).
Clean the terminal on each end of the cable with a fiber optic cleaning solution if you don’t see the right power input on the screen. Most testing kits will display both dBm and dB. The dB reading refers to the optical loss—the amount of information lost. The dBm measurement refers to the power of the overall signal (the amount of energy received). If the numbers on the screen are measured in OL or Ω, you have the meters set to test continuity, not insertion loss. Consult your manual if you can’t figure out how to change the test setting.
Some kits have dedicated cables for each meter. On other kits, the cables are interchangeable. Check each cable by inspecting the ports and covers to see if they’re stamped with the words “power” or “transmitter. ” These cables must be connected to the power source. The other cable may say “receiver” or “meter. ”
You may need to slide an adaptor on to the terminals of the test cable to connect it to the patch panel, depending on what type of fiber optic cable you’re testing. If you’re testing a cable with 2 ports on each end, only one of them must connect to the port with the jumper cable on the opposite side. Plug the second port into an empty slot next to the connected terminal.
Don’t worry if the numbers bounce up and down for a few seconds. This is simply the meter interpreting the results from the test.
You’re never going to add light from one end to the other, so this number can never be positive. On some testing kits, they put a negative sign (-) next to the number to indicate that you’re losing light/information, but some kits don’t bother since it can never be positive. A perfect reading is nearly impossible. You usually lose a little power and information through the terminal ports. The length of the cable can also cause some information to be lost.
This number can be positive since anything over 1 milliwatt is considered a positive charge. The cable isn’t technically adding power. If the readings are in an acceptable range and you’re still experiencing problems with the cable, the issues are likely not the cable itself.
