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4APSK signal

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(joined October 2014)
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how to figure out clear 4APSK constellation diagram?
I’m trying to do it as attached file. but not succeeded.

Can you give me advice or suggestion? And my drawn DPMZM is correct?

The two sub-modulators of the DPMZM are biased at null point. Can it generate two BPSK signals with unequal amplitude?
if no, can you give advice?

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Responses (12):

    • #14593
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      boldoo
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      how to figure out clear 4APSK constellation diagram?
      I’m trying to do it as attached file. but not succeeded.

      Can you give me advice or suggestion? And my drawn DPMZM is correct?

      The two sub-modulators of the DPMZM are biased at null point. Can it generate two BPSK signals with unequal amplitude?
      if no, can you give advice?

      Attachments:
    • #14619
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      Damian Marek
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      Hi Boldoo,

      I biased the signal at 4 V on both arms and provided a electrical gain of 2. In the attached file you will see the constellation diagram at the output which determines that is is working properly.

      It isn’t clear to me what you mean by two BPSK signals with unequal amplitudes. Could you attach an article or a plot of the waveform?

      Regards

      Attachments:
      +1
    • #14622
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      boldoo
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      Hi Damian,

      thank you very much your reply.
      My purpose is generate 4 APSK signal according to a paper.

      about two BPSK: there are 2 MZM in 1026edit.osd file. I wanna to check output constellation for each MZM.

      I have one paper about this:
      “The two sub-modulators of the DPMZM are biased at null point and driven by 10G Data1 and Data2, respectively, to generate two BPSK signals with unequal amplitudes. The two BPSK signals are then constructively added by adjusting Bias-C such that a 4APSK signal can be obtained.”

      So, how to check BPSK signals with unequal amplitudes in 1026edit.osd file?

      I’m looking forward your reply.

      • #14671
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        Damian Marek
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        Ok I understand the constellation diagram, still not sure exactly how to built the modulator. It should be possible to build this, do you have a diagram of how they set up their modulators and biasing? Do you have a link to the article?

        Thanks

        • #14716
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          boldoo
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          HI Damian,

          I have not link of this article.but I can write down text in here.

          “The Continuous wave is 4APSK modulated by a DPMZM, in particular, the two sub-modulators of the DPMZM are biased at null point and driven by 10Gbit/s Data1 and Data2, respectively, to generate two BPSK signals with unequal amplitudes.The two BPSK signals are then constructively added by adjusting Bias-C such that a 4APSK signal can be obtained”

          Can it help you make built modulator? I’m still trying to it in 1026edit.osd file. but not succeeded.

        • #14734
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          Damian Marek
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          Hi boldoo,

          I believe I did it, although I’m not entirely sure if it is the same design, but the results are the same. To make the unequal amplitudes I introduced an insertion loss on one of the modulators. I’m not sure how they did it in their design.

          Cheers

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        • #14766
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          boldoo
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          Dear Damian,

          you’re right. It is perfect. I have a question. these MZMs are peak point? or null point?

          what is push-pull point? is it different with peak or null?

        • #14810
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          Damian Marek
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          I have biased the MZM’s at peak point. I am not familiar with the push-pull point, but perhaps it is the same as quadrature point? If so it is the DC point that will give a 90 degree phase shift, so Vpi/2. Peak point is 0 Volt, null point is Vpi and quadrature is at Vpi/2.

          Cheers

    • #14623
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      boldoo
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      4 APSK constellation diagram should be like this fig.

      Attachments:
    • #15097
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      Hi boldoo,

      I thinsk this is the paper from here you want to implement.

    • #15098
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      attachment

    • #15099
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    • #15334
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      boldoo
      Participant

      thanks sir

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