Hello, everyone!
Today, I will continue to explain troubleshooting in PON networks using the OTDR instrument. This is the second article about this topic. Let’s get started.
Troubleshooting in PON networks is usually in-service testing. Min. 2 instruments are used for such test conditions:
PON meter and
In-service OTDR.
Classic OTDR instruments usually use 1310 nm and 1550 nm wavelength testing for dark fibers, in addition, they cannot perform testing in networks with optical splitters, etc. Therefore, special OTDR instruments are required - in-service OTDR. These OTDR services can test live optical fibers. They use most often 1625 nm or less often 1650 nm wavelength for testing. Another advantage of these OTDR instruments is the quality measurement of macro bends because high wavelengths are used.
The following figure shows the problem locations, the best OTDR test sites, and what type of ODTR instrument to use. This schematic summary is very useful for troubleshooting in PON networks.
In-service OTDR allows testing while services are operating normally. But the use of a WDM multiplexer/demultiplexer is required. OTDR uses wavelengths that are not used by PON systems. That is 1625 nm, and rarely 1650 nm (only in some countries, such as Japan). This type of OTDR can be used to test PON networks in any segment of the network - in the forward or reverse direction, at the user, or at any test point on the ODN network. Unlike the classic OTDR instrument, in-service OTDR has no problems with signals in the system. This OTDR has a long-pass filter that serves to protect the OTDR diode. This filter can be built into the device or as a separate element.
This
is the end of the second article. I
will continue to write about this topic in the next article >>Troubleshooting
in PON networks using the OTDR instrument (3).
In the following article, I will explain the testing of the PON network for all three cases using in-service OTDR.
I hope you learned something new!
Thank you!
