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BER of 4 PAM [Optical System]

(joined March 2014)
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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?

Responses (6):

  • #10185
    Damian Marek
    Moderator

    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?

  • #10186
    Damian Marek
    Moderator

    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.

    +2
  • #42518
    Profile Photo
    aadilqau
    Participant

    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

    • #42537
      Damian Marek
      Moderator

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

  • #42543
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    jagan padhy
    Participant

    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.

  • #42544
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    aadilqau
    Participant

    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.

  • #42567
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    aadilqau
    Participant

    Dear Damian,

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

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