I'm beginning to learn about the Constellation Modulator block, and just trying it out by setting up a 4-QAM system, with the constellation points arbitrarily set as : [-1-1j, 1-1j, 1+1j, -1+1j]

And the corresponding symbol map set as : [0, 1, 2, 3]

I tested this block by using a Vector Source with a value of '2', which is the third value of the symbol map. The corresponding constellation point (the third value in the list) --- which is 1+1j -- is indeed plotted.

Although, I also notice that another constellation point (which happens to be the first point in the list) - namely -1-1j is also plotted.

Is there a way to get the simulation to focus only plotting the 1+1j point? (that is - to plot a single point that corresponds to the the '2' value (ie. the 1+1j constellation point).

I've attached a screenshot showing the point that I assumed to see only (marked in green) ----- while the point marked in red seems to be plotted as extra. Any recommendations about what I can do to stop that extra constellation point (at -1-1j) from coming into that constellation plot? 

As a result of that extra constellation point coming into the picture ----- I think that the constellation plot also picks up points in-between the two constellation points ----- which comes up as points along a straight line. Basically - picking the trajectory in-between -1-j and 1+1j. I'm just trying to get a plot with 1+1j appearing in the constellation plot only.

Thanks very much in advance for any recommendations/help!

[![Vector '2'][1]][1]

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**UPDATE** - I have added waveform plots (obtained from a QT GUI Time Sink block) - which shows some interesting waveforms. These waveforms aren't what what we expect to see, right? Thanks in advance for more comments can recommendations about the Constellation Modulator block.

[![Vector 0][2]][2]
[![Vector 1][3]][3]
[![Vector 2][4]][4]
[![Vector 3][5]][5]

  [1]: https://i.sstatic.net/jOeoK.jpg
  [2]: https://i.sstatic.net/O70u5.jpg
  [3]: https://i.sstatic.net/c4BpJ.jpg
  [4]: https://i.sstatic.net/wLadN.jpg
  [5]: https://i.sstatic.net/rPkXR.jpg