What is OTDR?
OTDR (Optical Time Domain Reflectometer) is the most important test instrument for fiber optic network installation and maintenance. It launches optical pulses into fiber and analyzes backscattered light to measure length, loss, splice quality and fault location.
Unlike a basic optical power meter, an OTDR provides visual analysis of the entire fiber link.
Key Parameters
Pulse Width: Narrow (5-10ns) for high resolution at short distances. Wide (100ns-10μs) for long distance. Choose based on fiber length.
Range: Set to 1.5-2x the fiber length.
Averaging Time: 15-60 seconds typical. Longer = better SNR.
IOR Setting: Set fiber refractive index correctly (G.652 ≈ 1.4682).
Trace Interpretation
Key features on OTDR traces: starting reflection peak, linear attenuation slope, splice loss steps, connector events (loss + reflection), bend loss (loss only, no reflection), end reflection peak or fiber break.
Common Faults
Fiber Break: Strong reflection then trace ends.
Micro-bend: Loss step without reflection.
Dirty Connector: High loss + high reflection. Clean with fiber cleaning tools.
Poor Splice: Loss step >0.1dB.
Testing Tips
1. Use launch cable (500m+) to eliminate dead zone
2. Clean all connectors before testing
3. Test from both ends and average
4. Combine with optical power meter for end-to-end loss test
Conclusion
Visit Langzhi Technology for OTDR, fusion splicers, power meters and cleaning tools.
