Home Forums SYSTEM optisystem DUOBINARY

Viewing 4 reply threads
  • Author
    • #11395

      Hi all,

      Am looking for a complete design of duobinary modulation and demodulation system and working of it.

      Please help me out.

      thank you for the help.


    • #11452
      Damian Marek

      Here is an example of using duobinary modulation in OptiSystem. These are back to back systems, so all you need to do is add a transmission section to the design.

    • #11464

      Hi Damian Marek,

      I appreciate your great help.
      Can you also please help me out in more doubts in Optisystem.

      1) Theoretically for LEO/GEO satellites has min BER of 10^-9 to 10^-12.
      but when am trying out designs like QPSK,BPSK,Duo-binary systems in eye diagram analysis, Min BER shows ‘0’.
      how can i vary it or change it.

      2) In optisystem in ‘report’ where we can view graphs. Is there any possibility to compare to parameters like BER vs Eye height etc..
      How can i acheieve that.

      Please go through and help me out.
      As am running out of time for my project submission. am looking for more information on Optisystem.

      Please assist me on the priority.

      Thank you for the help.


      • #11478
        Damian Marek

        Hi Bindu,

        There are actually a couple ways that would make your BER 0. For example, the Duobinary design I sent earlier does not have a significant source of noise. To get a more realistic BER try adding a transmission link, like an Optical Fiber or a source of noise, like a White Light Source.

        You also have to be careful with which component you are using, which could be the BER Analyzer and Eye Diagram Analyzer or the BER Test Set. The first two calculate the BER by directly analyzing the eye diagram. The test set actually compares the generated bit sequence and the bit sequence recovered at the output of the system. For all of these components the bit sequence length plays an important role on the accuracy of the calculation/measurement, especially for the test set since it is possible for bit sequence lengths of less than 1000 to almost never have a bit error.

        Are you interested in plotting the BER vs Eye height and how it relies on the decision instant? Or do you want to plot the BER vs Eye height for systems with different noise levels or laser powers?

    • #11483

      Hi Damian Marek,

      Thank you for the quick response. Info was helpful.

      Yes i want to know both of them “plotting the BER vs Eye height and how it relies on the decision instant and plotting the BER vs Eye height for systems with different noise levels or laser powers”

      To make it more clear. Am doing my project on “Design & simulation of QPSK modulator for optic inter satellite communication”
      So now that i have QPSK design, I want to compare with other systems (BPSK,DUO binary,etc) and to show that QPSK is superior compared to others.
      So i need some graphs with respect to parameters like BER,Q factor, wavelength,eye height, power etc.

      Sorry for the trouble. Please assist me on the following.

      With regards,

    • #11603

      Yes Bindu,

      Damian is right. You can apply sweeps for any parameter like input power, distance etc.

      You can also do one thing, prepare one design (operating at 40 Gbps or you can go for WDM network if higher speed is required ) then apply sweeps to the two parameters : input power and distance.

      for e.g. input power = -5, -3, -1, 0, 1, 3, 5 dBm
      Distance = 50 Km x N spans (N = 1,2,3,4,5,6,7,8,9,10…..up to 100) , so total distance will be around 5000 km

      Now simulate this design with three different modulation schemes : BPSK, QPSK and Duo Binary
      I think, this will give sufficient no of results for your thesis or project submission. You can go for comparative analysis of all three modulation formats and come to know that QPSK is good.

      You can refer one paper also which also give the same kind of comparison but with three different modulation formats. here is the link:


Viewing 4 reply threads
  • You must be logged in to reply to this topic.