Different curve for log(BER)

[Mohamed Ben zegalamParticipant]

Hi All,

Is there any one know why are the curve of log(BER) different in the picture that is attached.

BER-1 and Eye diagram-1 are from one of the Optisystem 13 samples example.
BER-2 and Eye diagram-2 are from my design.

and which curve is good

Attachments:

1. 

   picture.jpg
   

[Mohamed Ben zegalamParticipant]

[Alessandro FestaParticipant]

Hi Mohamed,

for which particular design/example are these curves?

Regards,

Alessandro

[Mohamed Ben zegalamParticipant]

Hi Alessandro

Thanks for your reply. The example is WDM PON from Metro and Access system folder. My project is
CO-OFDM. I know they are different design, but I just want to know why both
of them has different shape of BER curve while they have almost the same
value.and is mine is consider as good or not.

I already get the explanation from optisystem support team, and here their answer

“The reason your eye diagram looks like this is its connected after the
decoder and the NRZ generator, which means your signals can only have “zero”
or “one” and that’s why they look ideal. For a more accurate view of the eye
diagram, you have to connect the visualizer before a decision has been made
on the electrical signal. However, you can’t really do that on the OFDM
because the output is not actually electrical. The decision is made inside
the OFDM component.

By the way, you are using our old OFDM component, which to be perfectly
honest, is not very good. For better results, please switch to our latest
OFDM components. They are a huge improvement over the old ones. I think you
have to be using at least OptiSystem 13.0.3 for them.”