Hello, everyone!
In today's article, I explain the use of the OTDR instrument in PON networks. This is the first article about this topic. PON networks are P2MP networks and are much more complex to maintain than P2P networks. Especially because PON networks have optical splitters, WDM modules, live fibers, short lengths of optical cables, and so on. Let's see!
PON networks can have one or usually 2 or max 3 optical splitters (cascaded PON network). There are generally 3 problems in the PON network, which are the following:
PON Case 1. One user has a problem with PON services. Possible problems are as follows:
1. problem between the user and the first optical splitter (problem with optical splitter, drop cable, ATB, fusion splices, dirty optical connectors, etc.),
2. problem with ONT device, and
3. problem in home's network (problem with optical or coaxial cables, optical or coaxial connectors, RF splitter, etc.).
In the next figure, we can see these problems – PON Case 1.
PON Case 2. For cascading PON networks (which is also the most common network), all users on one optical splitter do not have PON services. There are two possible problems:
1. Problem with the last optical splitter (optical splitter has high attenuation, bad fusion splices, bent optical fiber, dirty optical connector, and so on) and
2. Problem with the optical link between two optical splitters (problem with optical cable/fiber, bad fusion splices, dirty optical connectors, bent optical cable/fiber, and so on).
All these problems can be seen in the pictures below.
PON Case 3. All users don’t have PON services. Here the cause may be:
1. Feeder optical cable or optical fiber (damaged optical cable/fiber, excessively bent optical fiber, rarely bad fusion splice or dirty optical connectors),
2. Problem with the first optical splitter (attenuation of the optical splitter is greater than the prescribed value, bent optical fibers, dirty optical connectors, bad fusion splice, etc.) and
3. Problem with OLT in CO or headend (problem with PON port or slot or service board or all OLT or problem with passive elements such as patch cords, pig tails, optical connectors, WDM modules, and so on).
We see this type of problem in the following figure.
This is the end of this article. For more information about this topic >> Troubleshooting in PON networks using the OTDR instrument (2).
I hope you learned something new!
Thank you!
