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(joined August 2014)
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i made the project and represent code correctly but BER analyzer result not reasonable . i can’t figure the error

Responses (11):

    • #13274
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      Salwa Mostafa
      Participant

      i made the project and represent code correctly but BER analyzer result not reasonable . i can’t figure the error

    • #13351
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      Damian Marek
      Participant

      One of the main problems is that the channels at the output of the first 1:12 WDM Demux are not matching the input channels of your 3:1 WDM Mux. The channel frequencies are different. Make sure the WDM_Mux’s channels are correct for the receiver side as well. Finally, I think the LED transmitter will need a higher bandwidth to cover all the channels or you might want to use White Light source.

      Use the Spectrum Analyzer tool to verify everything is working!

      Cheers

    • #13382
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      Salwa Mostafa
      Participant

      Hi Damian

      i can’t figure where is the different in frequency between first 1:12 WDM Demux and first 3:1 WDM MUx

      Frequency[0] 1555.6
      Frequency[1] 1556.2 in first WDM Demux
      Frequency[2] 1557.8

      in WDM MUX Frequency[0] 1555.6
      Frequency[1] 1556.2
      Frequency[2] 1557.8

      the same thing at receiver side.

    • #13387
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      Damian Marek
      Participant

      Whoops sorry they are correct. But still use a white light source instead of LED, or use multiple LEDS. The bandwidth of your system is too large for the source.

    • #13393
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      Salwa Mostafa
      Participant

      Hi Damian

      i used white light, but i have a problem in the first WDM mux .
      can you check if the bessel filter center frequency and bandwidth is appropriate.

      Thanks in advance.

    • #13395
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      Salwa Mostafa
      Participant

      when i make sweep range every time i run the project the BER result is different .(different graphs (BER VS. range) ) ? how can i realize the appropriate system result ?

      • #13410
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        Damian Marek
        Participant

        Are you sweeping the range? This will definitely change the BER. If you mean that the BER is changing with the same settings then this is due to the noise randomness. Increasing the sequence length will lower the fluctuation of the BER due to the randomness of the noise.

    • #13419
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      Salwa Mostafa
      Participant

      Hi Damian

      what i mean when i made sweep range and try to draw it Vs. BER the first run result is the blue line ,when i made a second run for the same setting the red line produced. how can i reduce this so much change in results ?

      can you please answer my question in the fourth replay

      Thanks Damian very much.

      Attachments:
      • #13429
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        Damian Marek
        Participant

        Hi Salwa,

        This is due to “randomness” of the noise. In each separate simulation the noise generated is a little different. In each component that generates a noisy signal you can choose to keep the same seed for each simulation, so you will get the same result. In the Randomness tab of the Component Properties uncheck Generate Random Seed.

        On the other hand it is generally more accurate to keep the box checked and run the simulation with a longer bit Sequence Length. This will keep the randomness of the signal but each simulation run should give much more similar results.

        Regards

    • #13436
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      Salwa Mostafa
      Participant

      Hi Damian

      i used white light, but i have a problem in the first WDM mux .
      range of wavelength used 1550–1557.8 with .8 spectral width.
      which bessel filter center frequency and bandwidth for white light is appropriate.

      Thanks in advance.

      • #13457
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        Damian Marek
        Participant

        It’s hard for me to say. Try running multiple simulations (or a Parameter Sweep) and monitor the BER/Optical Spectrum of the system to determine the best choice!

        Regards

    • #13493
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      Salwa Mostafa
      Participant

      it’s working now. Thanks Damian very much for your help

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