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constellation map after 50km

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    • November 11, 2014 at 6:42 am #15186
      boldoo
      Participant

      dear all,

      after 50km optical transmission, how to keep constellation map as possible clear?
      For example, 4APSK signals generated by modulator. I can see it by Constellation visualizer. Mr.Damian knows it.

      I added 50km fibers and filters. but result is so bad. I tried as 1km fiber, but signal rotated almost -45 degree.

      what parameter should be consider in case of 50km? or 80. How to keep clear signal?

      if you have some idea, pls kindly share

    • November 11, 2014 at 6:45 am #15188
      Alessandro Festa
      Participant

      Did you match the reference signal wavelength in the fiber with transmitter and receiver wavelength?

    • November 11, 2014 at 7:09 am #15189
      boldoo
      Participant

      yes, reference wavelength is 1550nm at TX, RX and fiber and filters. same

    • November 11, 2014 at 7:21 am #15190
      Alessandro Festa
      Participant

      I remember I had this problem with 100G DP-QPSK but revision 13 solved it. Are you using 13 or 12?

    • November 11, 2014 at 7:26 am #15191
      boldoo
      Participant

      I’m using revision 13. do you remember which parameters set? and how about components ? amplifier, filter.. is that enough?

    • November 11, 2014 at 7:43 am #15193
      boldoo
      Participant

      when I deselect “group velocity dispersion” and “third-order dispersion”, constellation map showed almost clear. just attenuated.

      do you have idea about to correct the dispersion? need other components?

    • November 11, 2014 at 7:50 am #15195
      boldoo
      Participant

      Yes, I exactly need Dispersion compensating fiber. DCF. In optisystem, i didn’t find it.

      if you know it, please share me

      • November 11, 2014 at 4:21 pm #15216
        Damian Marek
        Participant

        Hi Boldoo,

        You can use a regular optical fiber component but manually change the dispersion. As in the attached project.

    • November 13, 2014 at 9:32 am #15331
      boldoo
      Participant

      thank you dears but it can’t change phase shift. I posted another forum, please review it.

      thanks

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