FIBRE TESTING
OLTS vs OTDR: What Each Fibre Test Proves
End-to-end insertion loss and event-level fibre characterisation are complementary measurements, not interchangeable shortcuts.
OLTS
An Optical Loss Test Set uses a source and power meter to measure total end-to-end insertion loss. Fluke describes OLTS as the standards-based method for Tier 1 fibre certification and comparison against the applicable loss limit.
OTDR
An Optical Time Domain Reflectometer sends optical pulses and analyses returned light. It can locate and characterise events such as connectors, splices and bends along the link. It is particularly valuable for fault location and deeper link documentation.
| Question | OLTS | OTDR |
|---|---|---|
| What is the total end-to-end insertion loss? | Directly suited. | Can estimate link loss but is not a replacement for the required OLTS certification method. |
| Where is the bad splice or connector? | Does not locate individual events. | Designed to locate and characterise events by distance. |
| Can I see reflectance events? | Not as an event trace. | Yes, subject to the instrument and test setup. |
| Should I keep the result? | Yes, with wavelength/reference information. | Yes, keep native trace files where required. |
Field sequence
Inspect and clean before testing. Establish the correct pass/fail limit and reference method. Use OLTS for the required end-to-end loss certification. Use OTDR when the project requires characterisation or when loss/fault location needs to be isolated.
Technical references
These sources support the standards, test-method and manufacturer-specific statements on this page. Project specifications and current manufacturer documentation take precedence for a real installation.