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 second article about problems with ODN. In the last article, I explained - feeder/distribution/drop fibers are broken.
As I said in the last article, 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 problems with dirty optical connectors.
2. Dirty optical connectors
The most common problem at the ODN is dirty optical connectors. If we design and build the ODN with optical connectors, we have to make sure the optical connectors are clean.
Dust is all around us. Therefore, even new connectors need to be cleaned. Cleaning is mandatory during installation and measurement/testing. Dirty optical connectors can introduce big attenuation and even link interruptions.
A typical connector connection introduces attenuation up to 0.5 dB. If the optical connectors get dirty the attenuation can reach a value of 4-5dB, sometimes even more. These attenuation values often lead to service interruptions. First, CATV stops doing (if we use that type of service), after that all other services. Or during installation, due to dirty optical connectors, there is a large attenuation and the ONU is not visible from the OLT.
Dirty optical connectors in addition to introducing a large attenuation and can lead to service interruptions, dirtiness can damage the surface of optical connectors. As a result, the optical connectors become unusable.
Never touch the surface of the optical connector with your hands! The oil from the hands passes to the optical connectors.
With a microscope, we can check optical connectors – dirtiness and damage surface. There are many modern microscopes with special software for analysis. Work with these instruments is very easy.
We can easily and simply determine the cleanliness and possible damage to the connector. After that, we either replace the optical connectors (if they are damaged) or clean them (if they are dirty).
During system operation, the optical connectors become dirty. Increased attenuation at the connector connections can be detected by OTDR.
There are many methods for cleaning. We can use the simplest method with alcohol (99% pure) and wipe, or better solutions with a wet method with special effective fluid and effective wipe or some dry method such as one-click cleaner.
After we clean optical connectors or change optical connectors (when I say we need to change the optical connectors, I think to change the patch cords), we must check optical power with the PON meter (or by some other method, e.g. remote reading optical power on ONU). If we get good values for optical power, we fixed the problem. Sometimes the cleaning needs to be repeated.
In the following pictures, we can see all of these that I talked about. In figure 1, we can see 4 photos on the left site show dirty and damaged optical connectors, and one picture on the right side shows a clean optical connector. The next figure shows a clean optical connector is in the upper left corner. All others are dirty optical connectors. We can see a different type of dirty. Figure 3. shows the propagation of the signal when the connector is clean (left site) and dirty (right site). The last two pictures show tools for cleaning optical connectors.
Figure 1. Photos of optical connectors
(http://www.datastrait.com/blog-news/5-facts-about-your-fiber-optic-cable-connection-cleanliness)
Figure 2. Photos of optical connectors
(http://www.fiber-optic-tutorial.com)
Figure 3. Propagation of signal
(https://www.mdpi.com/1424-8220/18/5/1408/htm)
Figure 4. Different tools for cleaning optical connectors
(https://www.aflglobal.com/Products/Test-and-Inspection/Fiber-Inspection-and-Cleaning/Fiber-Optic-Cleaning/FCP2-Field-Portable-Connector-Cleaning-Kits.aspx)
Figure 5. One click cleaner
(https://nexus-net.info/tips-on-keeping-fiber-optic-cable-clean/)
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 (5)
ONU failure to go online – Problems with ODN (6)
ONU failure to go online – Problems with ODN (7)
ONU failure to go online – Problems with ONU (8)
