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constellation map after 50km

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(joined October 2014)
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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

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Responses (8):

    • #15186
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      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

      Attachments:
    • #15188
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      Alessandro Festa
      Participant

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

    • #15189
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      boldoo
      Participant

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

    • #15190
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      Alessandro Festa
      Participant

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

    • #15191
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      boldoo
      Participant

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

    • #15193
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      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?

    • #15195
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      boldoo
      Participant

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

      if you know it, please share me

      • #15216
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        Damian Marek
        Participant

        Hi Boldoo,

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

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    • #15331
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      boldoo
      Participant

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

      thanks

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