Home Forums SYSTEM How to improve EVM value

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    • #22751
      Tayyab Mehmood
      Participant

      Good-evening everyone,
      I need to improve the EVM(%) value of 16-QAM 4-SCM based simple optical system with SMF of 5 Km without using DSP components at the receiver side, kindly suggest me the changes in the parameters as well as the other components to improve the EVM (%) value.

    • #22810
      Ashu verma
      Participant

      Hello tayyab
      Since EVM is generaly a deviation of point at receiver side from ideal one,you can analyze it by incresing power.i am not able to open your file,but reccomend you firt try to simulate the system without fiber of 5 km,see the evm directly at receiver side.if you get good evm then try the transmission by boosting the signsl using edfa .i think this will help ypu.

    • #22812
      Alessandro Festa
      Participant

      Hi Tayyab, have you tried to decrease the noise of the electrical amplifier? It seems too close to the signal level to me.

    • #22829
      alistu
      Participant

      Hi Tayyab,

      Increasing the power using optical amplifiers such as EDFAs is a good way, but optical and electrical amplifiers have a noise figure in reality which might make further problems for you. I suggest that you also boost the launched power by increasing the laser power on transmitter side as well.

      Cheers

    • #22831
      Ashu verma
      Participant

      Hi tayyab,alessandro give a good point, and consider the points of alisthu which are almost similar to my first reply.

    • #22853
      Tayyab Mehmood
      Participant

      1. I simulate the whole system without going into the optical domain but I did not get the improved results.
      2. I also sweep the input power, data rate, frequency spacing between each electrical carrier of 4-SCM, EDFA gain and the gain & noise power of electrical amplifiers at the transmitter side as well as at the receiver side but did not get the improved EVM value. I am still working on it..

      • #22854
        Alessandro Festa
        Participant

        Can you attach your file without the optical domain?

      • #22855
        alistu
        Participant

        I ran the optisystem file you have attached and got wrong results. I think the priority in here is to correct the system, and then improve EVM if it was necessary. And it is not something one would be able to modify by changing the aforementioned parameters. I myself am currently reading more about SCM OFDM and will let you know if I find the problem with your simulation.

    • #22863
      Tayyab Mehmood
      Participant

      Here is the File without optical domain

    • #22865
      Tayyab Mehmood
      Participant

      Hi alistu, would you suggest me the corrections to do in the optical system.

    • #22943
      alistu
      Participant

      Hi Tayyab,

      I am sorry I might have made a mistake then. But may I ask why you haven’t used any BER test sets or a haven’t used any method to be able to calculate the BER of your system? In other words, how would you evaluate the performance of your system in terms of BER now? I suggest that you do so.

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