Home Forums SYSTEM Negative SNR in OFDM based FSO links

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    • #49530
      Satinder Kaur
      Participant

      Hi,

      I have modeled OFDM based FSO transmission link by replacing optical fiber component with FSO component in OFDM modulator example given with Optisystem 14.2 samples. I am analyzing the effect of increasing link range on the SNR of the received signal (which I have calculated using Electrical carrier analyzer connected to Quadrature modulator at the receiver side).
      The SNR reduces with increasing distance (as expected)and after a certain distance gets negative (which should be zero as suggested by previous published literature).Kindly look into my project file and suggest what is wrong with the system. Also, I am not sure if connecting Electrical carrier analyzer to Quadrature modulator is the correct way of computing SNR or not.
      I am attaching .osd project file along the mail.

      Thanks in advance.

      Regards,
      Satinder

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    • #49679

      Hi Satinder,
      you plotted SNR in db. so negative sign means the signal is less than the noise which is meaningful.
      if you have it in absolute value the lowest value will be zero as you expected.

      Hope that clarifies your concern.

      thanks
      Mohamed

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