Hello,
Today I would like to share with you when the ONU receiving optical power difference is too large, causing the ONU to fail to go online.
Symptom
Networking: The system adopts two-level optical splitter, after the first-level optical splitter is 1:2, a 1:16 optical splitter is connected all the way, and one of them is connected to an ONU.
During the deployment at a certain site, it was discovered that all ONUs could not go online except for one ONU. The received optical power of these ONUs is relatively small, but still within the sensitivity range.
Reason
The optical power received by the ONU is greater than the overloaded optical power.
The optical power received by the ONU is less than the sensitivity value.
· Abnormal attenuation on the ODN line.
Steps
1. Measure the received optical power of the ONU, and the received optical power of the ONU that can go online is -7dBm, while the received optical power of other ONUs is -23dBm.
2. Calculate the dynamic range of the optical power of the entire ONU network, that is, the difference between the maximum received optical power and the minimum received optical power of the ONU ((-7dBm)-(-23dBm)=16dB), which is greater than 15dB. It is inferred that the ONU optical power difference is too large, causing the ONU with lower power to fail to go online. As shown in Figure 1.
Figure 1 The optical power difference is too large
3. Add 10dB light attenuation in front of ONU0, and other ONUs can go online normally.
4. The system runs for a week, and the ONU goes online stably.
Suggestions
The protocol requires that the dynamic range of the optical power received by the ONU should be less than 15dB, that is, the optical power attenuation of the PON port and any two ONUs cannot differ by more than 15dB.
You are welcome to leave a message and exchange in the comment area. Thank you!
