# Calculation of the total input optical power of an OA board

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The total input optical power of an OA board can be calculated using the following formula: Total input optical power = Single-wavelength nominal input optical power + 10lgN (N: number of in-service wavelengths).

###### Other related questions:

Nominal single-wavelength input optical power for OA boards on BWS 1600G?
Suggestion:
What is the nominal single-wavelength input optical power is determined for OA boards of the BWS 1600G? Answer:
Strictly speaking, there is no definition of nominal single-wavelength optical power for OA boards. The optical power is determined as follows:
To increase the signal-to-noise ratio, the incident optical power and receive optical power must reach the maximum as possible.
A 400G OAU board is used as an example.
The maximum incident optical power is 20 dBm and 40 wavelengths are supported. Therefore, the maximum single-wavelength output optical power is 4 dBm.
The BA gain is 19 dB, and therefore the single-wavelength input optical power of the BA board is defined to -15 dBm.
A VOA and DCM need to be added between PA and BA boards, the minimum VOA attenuation is 3 dB, and the maximum DCM attenuation is 12 dBm. Therefore, the minimum single-wavelength output optical power of the PA board is as follows: -15 + 12 + 3 = 0 (dBm).
The C-band gain is 20 dB and the L-band gain is 19 dB, and therefore the maximum single-wavelength input optical power of the PA board is -19 dBm.
The attenuation of the maximum span is 36 dB, and therefore the minimum single-wavelength input optical power of the PA board is as follows: 4 - 36 = 32 (dBm).
Varying with span reaches, the single-wavelength input optical power of the PA board ranges from -32 dBm to -19 dBm. The gain of a PA board embedded with a Raman amplifier (OAU_R) is 10 dB, and therefore the single-wavelength input optical power is -9 dBm.

Whether an increase of the output optical power of the OA board at the upstream site if the input optical power of the local OA board is 4 dB lower than expected
You are advised to check the fiber patch cords or fiber adapters at the local site to increase the input optical power, or remove the VOA from the OA board to decrease the insertion loss.

Input optical power range of the OLP board
TN11OLP01: �?5 dBm to +7 dBm (single-mode)
TN11OLP02: �?5 dBm to 0 dBm (multi-mode)
TN12OLP01: �?5 dBm to +7 dBm (single-mode)
TN12OLP03: �?0 dBm to +23 dBm (single-mode)
TN12OLP04: �?2 dBm to +23 dBm (single-mode)

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.

Method used to convert between the optical power of multiplexed wavelengths and optical power of single wavelengths of an OA board
The relationship between the optical power of multiplexed wavelengths and optical power of single wavelengths of an OA board is as follows:
Optical power of multiplexed-wavelength signals = Optical power of single-wavelength signals + 10lgN
where N is the number of wavelengths for multiplexed-wavelength signals.

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