BER of 4 PAM [Optical System]

[Damian Marek]

Question:

I want to design a 4-PAM system using multimode fiber and including a spatial VCSEL transceiver. More importantly, how can I calculate the BER of such a system?

[Damian Marek]

Answer:

It is possible to setup a BER measurement for the 4-PAM link by using the BER Test Set component. The test set creates a binary bit stream and compares this stream with the received bit stream after the PAM sequence has been decoded and converted to a binary data signal format.

As expected, the BER performance of the link is very sensitive to the threshold amplitude settings within the M-ary Threshold Detector component. Also, if the bit rate is changed I recommend that you take a look at the Binary Sequence Visualizer and the Binary Sequence Visualizer 1. At 5 Gb/s, I noticed a delay between the 2 streams (about 0.25 ns), which I was able to correct by adding a delay compensation within the Data Recovery component.

I have enclosed a network design that has been setup for a 5 Gb/s link.

Attachments:

1. 4_PAM_with_VCSEL_over_MMF_and_BER_Test.zip

[Aadil Raza]

Dear Damian

Thanks for designing system for PAM 4. Could you please tell me how can we plot a general BER vs received optical power (variable) graph for this case? As we know that waterfall trend of BER curve.

Please reply I want this solution from you.

Thanks

[Damian Marek]

There is a tutorial in the OptiSystem Samples -> Introductory folder titled Parameters Sweeps – BER x Input Power which demonstrates this functionality.

[jagan padhy]

Dear sir,
As we know for a good optical system the BER value will be accepted below 10^-9,similarly what is the corresponding value of BER test set so that it can be accepted as good communication system? and how to get the Q-factor value from BER test set.

[Aadil Raza]

Dear Jagan

A very good question. I have also seen that in this design log of BER value is -0.2942966130050128? which should be -9 as you said for a good communication system. I am also looking for answers…

Damian as you said above that delay is compensated by adding a delay of .25 ns within the Data Recovery component.But in Data Recovery component delay compensation value is set to zero.

[Aadil Raza]

Dear Damian,

I would be grateful if you reply my above query. I am stuck here

[Leopoldo Coque]

Hello, can you help me? I want to design a link at 400 Gbps and how to perform a cosimulation with matlab in optisystem. THE IDEA IS THAT MATLAB WILL HELP US DO THE PAM4 ENCODING for the link at 400 Gbps

• This reply was modified 3 years, 8 months ago by Leopoldo Coque.

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