Tier 2 shots that stand up
Tier 2 (extended) certification adds OTDR traces to the OLTS numbers. Shoot at both system wavelengths, both directions, with launch + receive fibers, and store traces with full setup metadata (pulse, range, index of refraction, cable ID). Set the correct group index from the cable datasheet or your length readings will be fiction. Event thresholds (splice, connector, reflectance) are set to the project spec, and every failing event gets fixed and re-shot — not annotated away.
Locating a fault fast
For a suspected break: shoot from the nearest access with a medium pulse; the end-of-fiber event's distance, corrected by the cable's fiber-overlength factor (sheath vs fiber meters), lands you within meters. Confirm from the far end. For high-loss-no-break: compare the trace to the baseline; a new bend appears as a step that grows at 1550/1625 nm; a degraded connector shows rising reflectance.
The filtered ports of live PON
Testing live PONs uses 1625/1650 nm filtered OTDR so the shot rides below the traffic wavelengths without blinding ONTs. Splitters appear as large steps (~17.5 dB for 1:32) and everything beyond loses dynamic range — plan test points at the FDH.
Trace hygiene
Name files by route/fiber, keep the same index and thresholds across a project, and archive alongside OLTS results. Six months later, the baseline trace is the most valuable asset your customer owns.