How to choose and use an OTDR?

What Is OTDR?

OTDR (optical time-domain reflectometer) is used to test newly installed fiber links and detect problems that may exist in fiber links. The purpose of it is to detect, locate, and measure elements at any location on a fiber optic link. An OTDR needs access to only one end of the link and acts like an one-dimensional radar system.

What should we look for in an OTDR?

Fiber testing plays a significant role in ensuring the network is optimized to deliver reliable and robust services without fault.

For different test and measurement needs, there exist a great number of OTDR models, then how to select the right one? A comprehensive understanding of OTDR specifications and the application will help make the choice. Moreover, based on your specific need, you should answer the following questions before looking for an OTDR:

What kind of networks will you be testing?

-           P2P,P2MP,PON etc.

What fiber type will you be testing? Multimode or single-mode?

-          That will help you choose between OTDR’s with the right wavelenghts for your case.

What is the maximum distance you might have to test?

-          That will refer to the Dynamic Range of the OTDR. You might calculate your need by knowing how many FOSC’s and connections there will be on your trace and adding on the dB/km loss from the cable itself.

What kind of measurements will you perform? Construction, troubleshooting or in-service?

And when choosing an OTDR, you should take these factors into consideration:

Display Size—5” should be the minimum requirement for a display size; OTDRs with smaller displays cost less but make OTDR trace analysis more difficult

Battery Life—an OTDR should be usable for a day in the field; 8 hours should be the minimum

Trace or Results Storage—128 MB should be the minimum internal memory with options for external storage such as external USB memory sticks and SD cards

Modularity/Upgradability—a modular/upgradable platform will more easily match the evolution of your test needs; this may be costlier at the time of purchase but is less expensive in the long term

Post-Processing Software Availability—although it is possible to edit and document your fibers from the test instrument, it is much easier and more convenient to analyze and document test results using post-processing software

OTDR

Conclusion

An OTDR is a vital fiber optic tester for maintaining and troubleshooting optical infrastructures. When choosing your OTDR, first to figure out the applications that the OTDR will be used for, and then check the OTDR’s specification to see if it is suited to your applications. And don’t forget to consider those elements we stated in this article. Hope it would help when you hesitate to make your decision.