Hi, everybody!
I continue to explain all problems with connecting ONU. Today, I will talk about problems with ODN and how we can fix it. This is the fourth article about problems with ODN. In the last article, I explained – bent fibers and problems with optical splitters.
As I said in the first article about problems with ODN, there are the following problems:
Feeder/distribution/drop fibers are broken,
Dirty optical connectors,
Bent fibers,
Problem with optical splitters,
Connected connectors of different types,
Connected fibers of different types,
Bad splices,
Incorrectly designed networks or incorrectly realized networks.
Today I will explain connected connectors of different types and connected fibers of different types.
5. Connected connectors of different types
In optical systems, there are many different types of optical connectors (SC, LC, ST, E2000, MU, ...). In GPON systems, SC, LC, and E2000 are most commonly used. There are also differences in the way of polishing the surface of the connector – pc (physical connector) and APC (angled-physical connector).
We can not connect SC to LC or E2000, due to different shapes and dimensions. But we can connect optical connectors with different polishing the surface, e.g. SC/PC to SC/APC. This can make problems in the optical line. In this connection point, there is bigger attenuation than a normal connection. This can introduce enough attenuation that it may disable ONUs to connect to the OLT. With OTDR, we can see a reflecting event that is outside the permitted limits. This type of problem can lead to short service interruptions over time. The problem will be easily solved by replacing the connector–patch cord.
In the next pictures, we can see many different types of optical connectors (figure 1.), types of end faces (figure 2.), and connected connectors of different types (figure 3.).
Figure 1. Different types of optical connectors
(https://www.ad-net.com.tw/16-types-fiber-optic-connectors-choose/)
Figure 2. Types of end faces
(https://slideplayer.com/slide/5852725/)
Figure 3. Interconnected optical connectors of different types of polishing
(https://slideplayer.com/slide/5852725/)
6.Connected fibers of different types,
According to the number of modes they transmit, optical fibers are divided into single-mode – SM and multimode – MM. In very rare situations, different types of optical fibers may be mixed.
Generally, ODN is built using SM fibers. It is unlikely that an error of this kind will occur. Such problems are especially not expected in the feeder and distribution segment. Otherwise, OTDR would detect errors like this. The only place where an error can occur is while using a patch cord in a home installation. But again, the colors of the jacket patch cord for SM and MM fibers are different.
Thank you!
For more information, please click:
ONU failure to go online – Problems with OLT (1)
ONU failure to go online – Problems with OLT (2)
ONU failure to go online – Problems with ODN (3)
ONU failure to go online – Problems with ODN (4)
ONU failure to go online – Problems with ODN (5)
ONU failure to go online – Problems with ODN (7)
ONU failure to go online – Problems with ONU (8)
