I am trying to code a QPSK transmitter in VHDL but first I want to create one out of Simulink blocks and translate it into VHDL code. I am using an example project for the PlutoSDR as a guide.
When i run this project this is the output i am seeing on Constellation Diagram 1 & 2:
What's happening is the points on the diagrams are continuously moving in a "circular" way. I've uploaded two GIFs of the constellation diagrams 1&2 from my Simulink project.
The output of Constellation Diagram, however, does not move and looks like this:
This is the output of the example on the Mathworks website (guide) seen as "Constellation Diagram" in the block diagram above.
My questions: Why did i have to put "Single Task Rate Transmission" boxes into my project as suggested by Simulink? Why do Constellation Diagram1 and Constellation Diagram2 "dance" around like this? What am i missing?