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How long your OTDR can test?

When we purchase a OTDR, we meet the frist problem: how long this OTDR can test? Today, we share a tip to you:

Take the single mode OTDR with 1310/1550nm as example, in the actual test, the loss with 1310nm is near to 0.33dB/KM, the loss with 1550nm is near to 0.22dB/KM. We know during the test, the fiber quanlity, connector quality, connecting close or not, etc. all would infect the loss and then final test distance. 

Component loss reference:


Splicing point:The average fusion loss in both directions cannot exceed 0.08dB

Splitter:1/2 around 4dB, 1/4 around 7dB, 1/8 around 10dB, 1/16 around 13dB, 1/32 around 16dB, 1/64 around 19dB


So if you can know more information about your network, then you can make it more precision.

Here's the  formula is used to get the distance:  (OTDR dynamic range-Component loss)/Fiber Loss=Distance.

For example, EXFO Max-715B OTDR, 1310/1550nm, 30/28dB. If it is a very good network with one connector and 2 splicing points, the testing distance with 1310nm: (30dB-0.4-0.08x2)/0.33dB/KM=89KM.  The testing distance with 1550nm: (28dB-0.4-0.08x2)/0.22dB/KM=124KM. 



YOKOGAWA OTDR AQ1000 1310/1550nm 32/30dB AQ1000 Optical Time Domain Reflectometer - fusion splicer,splicing machine,otdr,fiber tool kits-TEKCN fusion splicer

Here we see, 1550nm is right for long test because of its low loss. We suggest, constructors test with both 1310nm and 1550nm while working.
If you have any otdr questions, please be free to contact us. at
We are  glad to discuss with you and improve ourselves.

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