VDV Works Virtual Hands-On Training
Fiber Optics Testing: Using OTDRs
Part of the VDV Academy Fiber Optic Training Programs


Read About OTDRs

 Dos & Don'ts



Take Data

Viewing the trace

Measure Loss

Modify Test Parameters

Compare Traces



More Useful References

 Understanding OTDRs

"Virtual Hands-On" Termination

"Virtual Hands-On" Testing

Test yourself

1. Identify the features shown in the OTDR trace:


2.What two parameters are measured by the OTDR ? (They are the X and Y Axes of the OTDR display.)


3. List two effects that will occur if a user increases the width of the OTDR pulse from the low range to the high range in the table below.

4. Besides measuring splice loss between the markers, most OTDRs can measure splice loss with another method. How do they do it?

In the trace below, where is the "dead zone" and how should the effect of the dead zone be accounted for?

dead zone

6. Which of the reflections in the trace below is a "ghost"? How do you know?

7. What is the effect of different backscatter coefficients on either side of a splice?

What is the instrument used to find faults too close for the OTDR to see?

What does the OTDR actually measure the length of and what problem does that cause?

How can you determine which of the event(s) in the trace below have overloaded the OTDR?

11. There are a number of fluids that work well as index matching fluids to reduce reflections. Which two can you buy almost anywhere?

What information makes cable plant testing much easier?

Check Your Answers


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