Difference in results in different layouts

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    • May 25, 2015 at 2:16 am #21120
      Abhishek Shrama
      Participant

      @Damian
      I am facing a problem with my system. Whenever I make a duplicate copy of system and simulate it, the results on BER analyzer gets changed. even I have unchecked the random seed generation still the problem persists and I noticed a changes from 0.1 to even 5 in quality factor.
      I am not able to make graphs due to this problem. Even I checked in some of examples in Samples the problem lies there also.
      What is the reason that when I duplicate a layout or even select all and paste it onto a new layout the results change.
      What to do to overcome this problem and make graphs accurately.
      I am attaching the file in attachment. Please do reply me fast.

      Attachments:
      1. Modified-first-system.osd
    • May 25, 2015 at 9:56 am #21136
      Damian Marek
      Participant

      You correctly disabled the generate random seed for the bit sequence generator, but there are other sources of random noise in your system. For example, the Laser and Photodetector PIN.

      Regards

      +2
    • May 26, 2015 at 12:18 am #21150
      Abhishek Shrama
      Participant

      Thankyou Damian.
      It solved my problem. but is it authentic to disable all noises(Signal- ASE, ASE-ASE, Thermal and shot noise) ?
      and what is the I have one more doubt regarding it. The noise generation is random. Then why does it not change everytime I simulate the system and changes only when I change the layout?
      and What should I prefer? whether drawing graphs with random readings or disabling all the noises and the take the readings?

      • May 26, 2015 at 2:12 am #21155
        Alessandro Festa
        Participant

        Have you tried to increase the sequence length?

      • May 26, 2015 at 8:43 am #21168
        Damian Marek
        Participant

        My simulation changes with each calculation if I have the generate new seed box checked. It might be possible that you are using an older version of OptiSystem?

        Regards

        • May 26, 2015 at 11:04 am #21175
          Alessandro Festa
          Participant

          Hi Damian, if you increase the sequence length to 512 the change between iterations becomes very small…is this correct?

        • May 26, 2015 at 11:59 am #21176
          Damian Marek
          Participant

          The variations will become smaller, but how small depends on the actual BER of the system. A noisier system will be more susceptible to random changes in the noise and there will be larger fluctuations in the calculated BER.

        • May 27, 2015 at 2:17 am #21189
          Alessandro Festa
          Participant

          Ok thanks Damian!

        • May 27, 2015 at 5:22 am #21192
          Abhishek Shrama
          Participant

          Thankyou damian. You are always so very helpful.
          It solved the problem. I was missing out the random seed boxes checked in PIN and laser. Thats why I was getting results changed everytime. Now I got over it and getting constant results.

    • June 4, 2015 at 3:22 am #21373
      GURINDER SINGH
      Participant

      I am also getting same problem…. random seed index have to be made zero??????

    • June 4, 2015 at 3:45 am #21374
      Abhishek Shrama
      Participant

      yes GURINDER you have to uncheck the random seed generation not only from PRBS but also from all components like PIN LASER etc. Then you will get constant results to make decisions.

    • June 4, 2015 at 7:47 am #21386
      GURINDER SINGH
      Participant

      okk….i have unchecked it….is the random seed index also made to be zero in each case??

    • June 4, 2015 at 10:43 am #21399
      K. Esakki Muthu
      Participant

      Thank you Guys, I too got the same problem and now I got cleared my doubt.

      Thanks to the optisystem forum

    • June 4, 2015 at 1:39 pm #21401
      GURINDER SINGH
      Participant

      have u made random seed index also zero?????

    • June 5, 2015 at 12:10 am #21402
      Abhishek Shrama
      Participant

      Hello Gurinder,You can make the value of random seed generator zero.If you will have same problem ater setting seed to zero then do same as Damian wrote in previous reply.

    • June 7, 2015 at 9:40 pm #21445
      Dr. MohammadMahdi Ariannejad
      Participant

      same problem goes here!!!!!

    • June 8, 2015 at 1:13 am #21458
      Abhishek Shrama
      Participant

      @ MohammadMahdi Ariannejad
      Please read the discussion above and follow the steps of switching off the random seed generation from generators of random noise.

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