I am trying to simulate 8QAM with (4,4) amplitude levels. I want to get a constellation like this:

enter image description here

What are the amplitude levels should I select for I and Q?

  • $\begingroup$ notice the 001, 010, 110, and 101 all form a square and notice 001, 101, and 011 form an equilateral triangle. that should give you an idea what the relative amplitudes are. the angles for all of the points in the constellation are multiples of 45°. $\endgroup$ Commented Oct 24, 2017 at 2:23
  • $\begingroup$ Also note that there are good reasons why this constellation is NOT commonly used. And the complicated decision boundaries are among those. So if you ask me, you "should" use amplitude levels that distort this constellation to look like a psk. $\endgroup$ Commented Oct 24, 2017 at 5:57
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    $\begingroup$ You can simply write a look-up table that maps tuples of 3 bits to in-phase and quadrature amplitudes. $\endgroup$
    – MBaz
    Commented Oct 24, 2017 at 13:01
  • $\begingroup$ @MBaz I tried, but I eneded up getting error in Simulinik. Can you give me the exact lookup table that I can map the values? $\endgroup$
    – JOKER
    Commented Oct 24, 2017 at 15:38
  • $\begingroup$ @banureddy That's a different question -- you don't mention simulink at all in your question. I don't use simulink. $\endgroup$
    – MBaz
    Commented Oct 24, 2017 at 18:02


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