Home Forums SYSTEM QPSK modulation, sequence lenght, samples per bit

QPSK modulation, sequence lenght, samples per bit

Profile Photo
(joined May 2015)
Participant

Hello

I’m making ROF with qpsk modulation. I need 2 Mb/s and 1800 MHz so I set bit rate to 2 Mb/s symbol rate to 1 Mb/s but I don’t know how to set sequence length and samples per bit. I have been trying bunch of different sets but I have never reached 1800 MHz. My carrier is always below 300 MHz. Could you give me advice how to properly set those parameters ? I have attached my project.

Best regards

Attachments:

Responses (9):

    • #21784
      Profile Photo
      Maciej Nowacki
      Participant

      Hello

      I’m making ROF with qpsk modulation. I need 2 Mb/s and 1800 MHz so I set bit rate to 2 Mb/s symbol rate to 1 Mb/s but I don’t know how to set sequence length and samples per bit. I have been trying bunch of different sets but I have never reached 1800 MHz. My carrier is always below 300 MHz. Could you give me advice how to properly set those parameters ? I have attached my project.

      Best regards

      Attachments:
    • #21791
      Profile Photo
      Alessandro Festa
      Participant

      Hi Maciej, what do you mean by “I have never reached 1800MHz”?

    • #21798
      Profile Photo
      Maciej Nowacki
      Participant

      Hello

      The highest frequency that I can get is about 300 MHz.

    • #21799
      Profile Photo
      Alessandro Festa
      Participant

      After setting bitrate and simbol rate, go to “Simulation Window” and choose “Set sample rate”. Now you can change the sample rate to >1800MHz.

      Does this answer your question?

    • #21800
      Profile Photo
      Maciej Nowacki
      Participant

      Yes, thanks 🙂 but I have one more problem. I have been trying measure BER but my BER analyser doesn’t work. Could you help me in that problem ?

      Attachments:
      • #21802
        Profile Photo
        Alessandro Festa
        Participant

        I will have a look at your file once in office…what do you mean exactly by “does not work”?

    • #21805
      Profile Photo
      Maciej Nowacki
      Participant

      I think that my BER is too good. I have attached my project.

      Attachments:
    • #21809
      Profile Photo
      Alessandro Festa
      Participant

      You are arriving at the receiver with high power and high OSNR…why would you expect a worse BER? I ran the simulation and it gives 1E-66

    • #21823
      Profile Photo
      Maciej Nowacki
      Participant

      Yes but I set optical fiber length to 160 km. I got very bad graph of constellation and very good BER (about 10^-30).

      Attachments:
    • #21826
      Profile Photo
      Maciej Nowacki
      Participant

      This is my graph showing dependency between length and BER.

      Attachments:

Login You must be logged in to reply to this topic.