Whether DCM modules are required on OAU boards or other boards that support dispersion compensation on a 40G or 100G transmission network


A 40G/100G ePDM-BPSK system is a type of coherent transmission system. DSP chips are configured at the receive end of the system to compensate for electrical-layer PMD and CD.
In a 40G DQPSK or another type of coherent system, DCM modules are still required to suppress the PMD and CD. In such as system, you can install a DCM module between the TDC and RDC ports of an OAU board. You can also use DCU boards to suppress the link dispersion.

Other related questions:
Whether coherent 40G boards require dispersion compensation, and dispersion tolerance of the LSQ board
No dispersion compensation is required for coherent 40G boards, and the dispersion tolerance of the LSQ board (non-coherent) is ±800 ps/nm.

Whether dispersion compensation is required for OTU boards
Dispersion compensation is not required on the WDM side of OTU boards. Dispersion compensation is generally performed between OA boards.

Differences in dispersion compensation between 40G coherent boards and 40G non-coherent boards
40G non-coherent boards use the TDC technology and the dispersion tolerance is 800 ps/nm. 40G coherent boards use the DSP technology and the dispersion tolerance reaches 60,000 ps/nm. A network deploying non-coherent boards must use DCMs for dispersion compensation. A network that uses only coherent boards does not need to use DCMs.

Methods for determining the over-compensation or under-compensation according to the dispersion compensation of the 40G board, and conditions for dispersion search
Query the WDM performance events. If the compensation value is negative, the line is under-compensated; if the compensation value is positive, the line is over-compensated.

Dispersion compensation range of TDC boards
The dispersion compensation of the TDC board ranges from �?00 ps/nm to +400 ps/nm.

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