OTDR Trace Analyzer Calculator

The calculator uses 0.35 dB/km at 1310 nm and 0.22 dB/km at 1550 nm because silica fiber genuinely scatters and absorbs light less at the longer wavelength — that's a physical property of the glass, not a measurement artifact. Selecting the wrong wavelength in the dropdown shifts the Expected Cable Loss baseline enough to make a marginal link look like it passes or fails when it's really just a mismatched assumption.

It doesn't measure each event individually — it takes the total event loss (measured total loss minus expected cable loss) and splits it 70/30 between reflective (connector-type) and non-reflective (splice-type) events to produce the Avg Connector Loss and Avg Splice Loss outputs. The chart's estimated connector and splice bars use a separate flat assumption (0.35 dB per reflective event, 0.05 dB per non-reflective event) just to visualize a plausible breakdown, so the two figures won't always line up exactly.

Loss Margin is the difference between the maximum acceptable loss (expected cable loss plus per-connector and per-splice thresholds plus a 1 dB safety margin) and your measured total loss. A positive margin means the link passed with room to spare, while a margin near zero or negative means the link is at or over its budget and the high-loss events deserve a closer look.

The pass/fail check only compares your total measured loss against a computed ceiling — it has no visibility into the shape of the trace itself, so a single bad splice or macrobend can be masked by other clean events averaging it out. This tool validates the overall loss budget, not the trace event-by-event, so a true fault diagnosis still requires reading the actual OTDR trace.