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Distance | dB Loss | Return Loss



CablesOne is a member of Fiber Optic Association (FOA) therefore we enforce cables testing based on FOA standard and TIA/EIA standard for cable testing verification. It is used to evaluate the performance of fiber optic components, cable plants and systems. As the components like fiber, connectors, splices, LED or laser sources, detectors and receivers are being developed, testing confirms their performance specifications and helps understand how they will work together. Designers of fiber optic cable plants and networks depend on these specifications to determine if networks will work for the planned applications.

After fiber optic cables are installed, spliced and terminated, it is required to be tested. For every fiber optic cable plant, the testing for continuity and polarity are required and end-to-end insertion loss to troubleshoot any problems. If it’s a long outside plant cable with intermediate splices, the verification of the individual splices with an OTDR test is required, since that’s the only way to make sure that each splice is good. (Please see our Company Tester equipment listing for the tester brand and model we use for cable testing).

Our technician perform all fiber optic insertion loss of an installed fiber optic cable plant performed with a light source and power meter (LSPM) or optical loss test set (OLTS) which is required by all international standards to ensure the cable plant is within the loss budget before acceptance of the installation.


  • For each connector, figure 0.3-0.5 dB loss for adhsive/polish connectors, 0.75 for prepolished/splice connectors (0.75 max from TIA-568)

  • For singlemode fiber, the loss is about 0.5 dB per km for 1300 nm sources, 0.4 dB per km for 1550 nm. This roughly translates into a loss of 0.1 dB per 600 feet for 1300 nm, 0.1 dB per 750 feet for 1300 nm.

  • For each splice, figure <=0.2 dB (Both applies for Singlemode and Multimode fibers)

  • For multimode fiber, the loss is about 3 dB per km for 850 nm sources, 1 dB per km for 1300 nm. This roughly translates into a loss of 0.1 dB per 100 feet for 850 nm, 0.1 dB per 300 feet for 1300 nm.

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For troubleshooting high loss in a cable, our technician is to make sure to reverse the fiber testing and test in the opposite direction using the single-ended method. Since the single ended test only tests the connector on one end, we can isolate a bad connector - it’s the one at the launch cable end (mated to the launch cable) on the test when you measure high loss. High loss in the double ended test should be isolated by retesting single-ended and reversing the direction of test to see if the end connector is bad. If the loss is the same, we will need to either test each segment separately to isolate the bad segment or, if it is long enough, by using an OTDR will able to identify the length and fault areas of the fiber segment.

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