The engineer measure the optical power on OPU-MON by 3 different devices:
1、Huawei OSA (-8.37dBm).the attached file "Huawei OSA.bmp"
2、Optical power meter (-8.4dBm)
3、EXFO OSA (-12.69dBm). the attached file "EXFO OSA.bmp"
The signle optical power measured by the Huawei OSA and Power Meter is almost the same.
But the total optical power measured by EXFO OSA is different from the total optical power measured by huawei OSA on OPU-MON. Why?
Huawei OSA calculate the total optical power of signal and noise.
So the total optical power equal the optical power measured by Optical power meter.
EXFO OSA only calculate the total optical power of signal.We can calculate the total optical power of signal according Pawg on the diagram.
When OSNR is very high (Noise is very low) and there are many wavelengths, the total optical power measured by huawei OSA and EXFO OSA will be almost the same.
The total optical power measured by huawei OSA and EXFO OSA have different consideration for noise.
The total optical power need to cosider noise affection.