Hello everyone!
This time, I will share with you the signal flow of the single-fiber bidirectional system.
How to connect fibers and signal flows in single-fiber bidirectional scenarios on an OTN Network?
What is the signal flow in the single-fiber bidirectional scenario of an OTN Network, and how to connect optical fibers?
Take the EX40 board of the OptiX OSN 1800 as an example to show you:
1. When the EX40 board is used in this application scenario, optical ports MD01 to MD20 form a group and optical ports MD21 to MD40 form a group. One group is used for receiving optical signals and the other is used for transmitting optical signals. The EX40 board can also multiplex and demultiplex 40 channels of optical signals when it is used with the TNF1ITL board. The following figure shows the signal flow of the EX40 single-fiber bidirectional scenario where no amplifier board is used:

2. When the EX40 board is used in this application scenario, optical ports MD01 to MD18 form a group and optical ports MD23 to MD40 form a group. One group is used for receiving optical signals and the other is used for transmitting optical signals. The EX40 board can also multiplex and demultiplex 35 channels of optical signals when it is used with the TNF1ITL board (Even wavelengths: MD01 to MD18, MD23 to MD40. Odd wavelengths: MD01 to MD17, MD23 to MD39). The following figure shows the signal flow when the EX40 single-fiber bidirectional amplifier board is used:

3. Precautions
a. In the single-fiber bidirectional scenario, the source and sink OTU boards must use different wavelengths. The transmit-end wavelength must be consistent with the EX40 MDXX. The receive-end OTU board uses a wide range of wavelengths.
b. In the scenario where the OA board is used, the OA board cannot directly transmit and receive multiplexed signals. Therefore, the MB1 board needs to filter out the 192.1THz to 193.8THz and 194.3THz to 196.0THz wavelengths and then amplify the signals separately. Therefore, four ports on the EX40 board are idle.
For more information on signal flow: Introduction To Common WDM Signal Flows
To learn more about WDM, please subscribe to Transmission O&M World.
Thank you!

