IPA process in case of a fiber cut
When a fiber cut occurs at point A, the system detects an R_LOS alarm at point R2. In this case, the system decreases the optical power of the signals transmitted from point T2.if the R_LOS alarm lasts for consecutive 500 ms counting from the time when the system detects the R_LOS alarm at point R2, the IPA function will be implemented to decrease the transmit optical power at point T2 within 700 ms. Consequently, the input optical power at point R1 decreases and the system will detect an R_LOS alarm at point R1. Finally, the system decreases the transmit optical power at point T1. In this manner, the optical power in the fiber where point A is located is in a safe range.
If the IPA function is configured at two OTM stations, the optical power of all OA boards in the optical multiplexing section (OMS) will decrease when the IPA function is started in case of a fiber cut.
when CRPC boards are used in the system, the backward pump optical power is high. Therefore, after the detection board in an IPA pair detects a fiber cut, both the laser on the control implementation board and the backward pump laser on the CRPC board must be shut down, ensuring that the optical power on the entire line is in a safe range.
When CRPC boards are used in the system, the optical power of the scattering signals is very high. In this case, the system cannot determine whether a fiber cut occurs. However, this issue can be resolved by setting the OTU and OSC boards as auxiliary detection boards. The OTU board refers to the OTU board downstream to the OA board.
