An OTDR set up for single-mode will not produce useful results on multimode fiber, and vice versa. Wavelength, refractive index, pulse width, and event detection thresholds all need to match the fiber under test. This guide walks through the right settings for both fiber types and the differences. However, choosing the wrong OTDR wavelength, launch conditions, or test methodology for a given fiber type can produce misleading results, fail acceptance testing, or miss real-world performance degradation. Testing both types is possible, though there are some significant differences and considerations to remember. It can verify splice loss, measure length and find faults. Later, comparisons can be made. OTDR settings are a balance between dynamic range, acquisition time, spatial resolution and accuracy. To minimize testing time, compromises must be made on accuracy (detecting low loss. The OTDR trace provides an as-built drawing or map of a system, and as such it is the perfect tool for finding problems.
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