Excessively large wavelength deviation reported by the WMU boards of OSN 6800


The LSX boards with adjustable DRZ reported the WAVE_LEN_OVER alarm, whereas the ones with NRZ fixed wavelengths did not report the alarm. When an optical spectrum analyzer was used for wavelength testing, the wavelength deviations are within the allowed range. No excessively large wavelength deviation is detected. (OSN 6800 NE version, NMS version T2000V2R6)
Root cause:
The wavelengths from the light source of the DRZ adjustable optical modules are controlled by the core temperature without human interference. Wavelength deviation adjustment should not be performed by the software to such modules. V100R003C02B028 does not monitor adjustable optical modules for wavelength deviation, and the deviation threshold was changed from 0.5 GHz to 5 GHz.

Other related questions:
Functions of spectrum analyzer units MCA and WMU on OSN 6800
Question: When an OSN 6800 device is used to construct a new network, two spectrum analysis units are configured: multi-channel spectrum analyzer unit (MCA) and wavelength monitoring unit (WMU). The functions of these two boards seem to be overlapped. How do we understand these functions? Answer: 1. MCA boards are classified into MCA4 and MCA8, which provide four and eight ports respectively. An MCA board is mainly used to detect channel optical power, center wavelengths, OSNR, and the number of wavelengths on an optical path. Similar to an optical spectrum analyzer, an MCA board reports the detected information to the system control board for fault diagnosis and monitoring. It can also be used together with other boards to achieve the automatic power equilibrium (APE) function. 2. A WMU board works with the system control board to lock wavelengths and monitor the transmit-end OTU wavelength deviation. The monitoring results are transmitted to the system control board through mailbox. Then, based on the wavelength configuration table, the system control board determines whether wavelengths need to be adjusted. If the wavelengths need to be adjusted, the system control board transmits the adjustment information to the OTU board to complete the wavelength deviation adjustment. 3. An MCA board can be configured to monitor the transmit end and receive end.4. A WMU board can be configured only at the transmit end, because it is used to adjust wavelength deviation of the OTU board at the local station with the system control board. 5. An MCA board is easy to maintain. A WMU board provides functions. To use OTU boards with 100 GHz spacing in an 80-channel system in the C band, WMU boards need to be configured to lock the working wavelength of OTU boards. If the working length stability of OTU boards with 100 GHz spacing cannot meet the requirements of an 80-channel system, WMU boards can be used. Suggestion and conclusion: An MCA board is used to monitor optical signals. A WMU board is used to monitor optical signals and lock and control the OTU wavelength with the system control board.

Maximum wavelength offset of an 80-wavelength OSN 6800 system
Based on the nominal operating wavelength, the wavelength offset of an 80-wavelength OSN 6800 system must be within ±0.08 nm.

Maximum number of wavelengths that a MUX/DEMUX board can process in the OSN 6800
A maximum of 80 wavelengths can be processed by the ITL board. The ITL board multiplexes 40 odd wavelengths and 40 even wavelengths of M40 boards into 80 wavelengths, and then demultiplexes the 80 wavelengths into 40 odd wavelengths and 40 even wavelengths and sends the wavelengths to D40 boards.

Threshold of the input optical power of a WMU board in the OSN 6800
For the WMU board in the OSN 6800, its single-wavelength input optical power must be in the range of �?6 dBm to �?6 dBm.

Nominal single-wavelength input optical power of the OSN 6800 HBA board in a 40-wavelength system
The nominal single-wavelength input optical power of the HBA board in the OSN 6800 is as follows: -22 dBm (in an 80-wavelength system) -19 dBm (in a 40-wavelength system) -13 dBm (in a 10-wavelength system)

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