Home Forums SYSTEM 4-PSK and 4-QAM in FSO Links

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    • #68316
      Amit Grover

      Hi everyone,

      I have designed an OFDM-based FSO lnk. 4-QAM and 4-PSK modulation schemes are the same, since both have same constellation graph. Then why does 4-QAM performs better than 4-PSK in terms of BER of the received signal at the same system and link parameters in my project? I am attaching the .osd file of my system.

    • #68332
      Ahmad Atieh

      Dear Amit,
      I’ve checked your project and swept the FSO range from 0.1km to 2km. The difference is minor between the two systems. which is expected because the symbols are far from each other and there is no stress on the detection system. However, the PSK requires amplitude/phase information compared to the QAM which requires amplitude only. That makes QAM slightly better in your case.

    • #68360
      Amit Grover

      Dear Ahmad,

      Thank you for clearing my doubt.

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