Failure to support the ALS function by RPC

Question:
Why RPC does not support the ALS function?
Analysis:
To support the ALS function, RPC must be able to accurately detect fiber cuts. Theoretically, there are two methods of detecting fiber cuts:
1. Check optical power. If the RPC receive optical power is less than a certain value, a fiber cut occurs.
2. Check the reflection value. If the RPC receive reflection power is greater than a certain value, a fiber cut occurs.
The RPC receive optical power is dependent on the number of wavelengths, line attenuation, and RPC gain. If a fiber cut point is far from the RPC, the pump light in optical cables can be greatly amplified. In this case, the RPC receive optical power contains large noise power. For the reasons above, the difficulty in determining a fiber cut based on the power strength lies in that a critical power value for judging a fiber cut cannot be determined. To be specific, it is unreliable to determine an RPC fiber cut based on the power strength.
The reflection value is dependent on the end face of the fiber cut point. There are two types of fiber cuts:
a. A connector is disconnected. If a PC connector is disconnected from an optical port, large reflection power is generated. A fiber cut can be determined based on the reflection power. However, the LINE port of the RPC board is equipped with an APC connector that is applicable to high-power applications. Small reflection power is generated even though the APC connector is disconnected. Therefore, the reflection power cannot be used as the basis of a fiber cut.
b. An optical cable is broken. The reflection power generated upon a cable break is random and is small in most cases. Therefore, the reflection power cannot be used as the basis of a fiber cut.
Based on the preceding reasons, it is unreliable to implement the ALS function only using the RPC board.
Answer:
Use the IPA function to disable the laser of the RPC board upon a fiber cut.
Suggestion and conclusion:
None

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