Home Forums SYSTEM BER analyzer

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    • #27158
      lavanya krishnan
      Participant

      in ber analyzer results there is a element called “penalty:Q factor from Min.BER at user defined decision instant(dB)”
      what does It mean? is it same as “max Q factor” can we use it to express the quality of transmission?i have attached the picture below

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    • #27168
      alistu
      Participant

      Hi Lavanya,

      The BER analyzer chooses the best instant with the widest eye opening as the decision instant to calculate max. Q-factor. Now if you define any other instant, your Q-factor would not be as much, so you have to increase the power as a penalty to get the same Q-factor as the max. Q-factor.

      Regards

      +2
    • #27200
      lavanya krishnan
      Participant

      hi alitsu,
      but if I use “max q factor” in a 16 channel wdm(I have attached it below) system I get maximum q factor of 4.9 but if in case of “penalty:Q factor from Min.BER at user defined decision instant(dB)” I get maximum q factor of 33 .what can I use to define the quality of transmission

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      • #27203
        alistu
        Participant

        i have started simulating your file, but it seems it will take a lot of time to finish. Can you please attach a screen shot of the result with the obtained value (the one you have been referring to and you have shown in the topic main post attached image)?

    • #27208
      lavanya krishnan
      Participant

      thanks for helping

      • #27211
        alistu
        Participant

        The y-axis shows the power penalty in dB, and not Q-factor. It means that, for example, for the transmission line of 140 km, you need to use 60dB more power I order to maintain the same max. Q-factor (which is about 4.8 according to your Q-factor graph) for the user defined decision instant.

    • #27214
      lavanya krishnan
      Participant

      thanks but in case of q-factor it is very low why? as far as I know acceptable q-factor is 6-9?

      • #27218
        alistu
        Participant

        I wanted to ask whether this is the system you had formerly asked for suggestions for performance improvement. I once used DCF and once reduced the WDM laser linewidth to 0.1 MHz, which is acceptable for low power CW lasers, but neither of these methods made a remarkable change in the Q-factor. However, I suggest that you go with laser linewidth reduction and see if that helps.

    • #27219
      lavanya krishnan
      Participant

      I have read many research paper in those paper q-factor is always more than 10 but when I do the same simulation in optisystem q-factor is always less than 6.i have attached some papers and simulation files if u have time please point out my error in simulation

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