This guide walks the full process -- calculating the budget on paper, setting up the equipment, performing the bidirectional measurement, comparing to the spec, and documenting the result. The procedure is the same whether you are testing one fiber or a hundred. To be able to judge whether a fiber optic cable plant is good, one does a insertion loss test with a light source and power meter and compares that to an estimate of what is a reasonable loss for that cable plant. Allowable signal loss can be so low that seemingly small issues can cause excessive errors in network transmission. These fibers are most commonly made of glass and are very thin, typically less than a tenth of the width of a human hair. Once the cable plant components are chosen, the next step is to ensure the choices are correct and the link will work as designed.
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