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M-ary encoding

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    • November 6, 2015 at 7:28 am #27476
      Prarthana Kashyap
      Participant

      Hi everyone,
      I studied about digital modulation techniques and found that “In digital communications, the modulating wave consists of binary data or an M-ary encoded version of it and the carrier is sinusoidal wave.” so my question is what is M-ary encoding how can we do M-ary encoding in optisystem, I have found here a M-ary encoder but how does it works. please anyone explain this.

      With regards,
      Prarthana Kashyap

    • November 6, 2015 at 8:02 am #27478
      Abdallah Ismail
      Participant

      It is simply digital to analog converter.

      • November 6, 2015 at 9:29 am #27483
        Prarthana Kashyap
        Participant

        Hi abdallah, if it is simply a digital to analog converter the an analog signal is going to modulate the light in case of optical communication, then it is not a digital modulation. Will you please explain in details. Thank you..

        Regards,

    • November 6, 2015 at 8:48 am #27479
      alistu
      Participant

      Hi Prarthana,

      Digital signals in OptiSystem are either in binary form or in M-ary form. When the digital data only has two logical values of ‘0’ and ‘1’, it is called binary and otherwise, the data is M-ary. Many encoding components such as QAM receive binary input data and generate M-ary data in the output.

      Regards

      • November 6, 2015 at 9:36 am #27484
        Prarthana Kashyap
        Participant

        Thanks Alistu for the reply, How the M-ary data will look like, can you explain with some graphical representation how the bits will look like. or in case of M-ary encoding there will be more than one threshold. I have seen in many cases that the threshold detector is having some more values of threshold i.e. my question is will it require multiple no of threshold values in case of detection.

        Regards

        • November 6, 2015 at 1:04 pm #27496
          alistu
          Participant

          If the M-ary signal has more than two levels, then the threshold detector needs more than one threshold. For example, for a signal formerly produced by a 4-QAM encoder, you only need one threshold, since the M-ary values should be either ‘1’ or ‘-1’ and therefore, there are only two levels for the signal.

        • November 6, 2015 at 11:01 pm #27501
          Prarthana Kashyap
          Participant

          Thank you alistu for the reply, I am still waiting for the circuit which can produce such kind of multilevel signals. because I am not finding the circuit in the help section of the component also.

          Regards,
          Prarthana

        • November 7, 2015 at 2:22 am #27505
          alistu
          Participant

          I don’t think it has special circuitry different from an electrical component making a multilevel signal. In OptiSystem, signals have been divided into binary, M-ary, electrical and optical and the format of the vectors produced in each case are different. So it refers to the format of vectors rather than the circuitry.

          Regards

    • November 6, 2015 at 9:51 am #27485
      Dr. Dhiman Kakati
      Participant

      Dear Prerthana, I have attached here with some m-ary visualizer graph, from it you can understand how the M-ary encoded signal look like, regarding how to generate the M-ary pulse the internal circuitry of M-ary pulse generator is not there but you may find some mathematics in the components pdf at page no. 279, the conditions are explained there very nicely. the method of generation is same as that of QAM pulse generator any other of the same kind in the library. Thanks.

      Regards

      • November 6, 2015 at 9:54 am #27486
        Dr. Dhiman Kakati
        Participant

        again the attachment failed. please find here..

        Regards

    • November 6, 2015 at 11:12 am #27490
      Prarthana Kashyap
      Participant

      Thank you Dhiman.. I am still looking for the circuit for generation of this king of pulse..

      Regards

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