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not getting the output waveform for oqpsk example

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(joined July 2015)
Participant

hi
I am not getting the waveform of OQPSK, given as example in optiwasystem 13(Evaluation version) sample.
but getting the output in optisystm 7.

why i am not getting in optisystem 13??
please find the attachment and help.

Responses (4):

    • #26146
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      Debanjan Sarkar
      Participant

      hi
      I am not getting the waveform of OQPSK, given as example in optiwasystem 13(Evaluation version) sample.
      but getting the output in optisystm 7.

      why i am not getting in optisystem 13??
      please find the attachment and help.

    • #26150
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      alistu
      Participant

      Hi Debanjan,

      The reason for the simulation not showing any resluts at the receiving end is that the cut-off frequency of your quadrature demodulator is not matched with your bit rate and therefore, almost all the signal is filtered. I increased it to 0.75*bit rate and the results are there in the output. I am not sure about the validity of the system results, though.

      Regards

    • #26152
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      Debanjan Sarkar
      Participant

      Dear alistu
      I have changed the cutoff frequency but the output waveform is different from input sequence.
      You can check with lower no. of bit sequence suppose 8 bit and sample per bit= 4.
      regards

      • #26158
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        alistu
        Participant

        Indeed, the increase in the quadrature demodulator cut-off filter would just stop signal being filtered and therefore provides an output. It is strange that you managed to get results in OptiSystem 7, as the quadrature modulator output was showing signal with virtually zero amplitude.

        I have noticed here is also a problem with decision boundaries. Could you modify them first according to your design?

    • #26157
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      MHD NA
      Participant

      Try to rebuild it on new project in optisystem 13

      Regards,

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