Communication Systems - QPSK - Signal Constellations

 clear

clc;
close;
M =4;
i = 1:M;
y =cos((2*i -1) *%pi/4)-sin((2*i -1)*%pi/4)*%i;
annot = dec2bin([0:M-1],log2(M));
disp (y, 'coordinates of message points')
disp (annot,'dibits value')
figure;
a = gca();
a.data_bounds = [ -1 , -1;1 ,1];
a.x_location = "origin";
a.y_location = "origin";
plot2d (real (y (1) ),imag (y (1) ) ,-2)
plot2d (real (y (2) ),imag (y (2) ) ,-4)
plot2d (real (y (3) ),imag (y (3) ) ,-5)
plot2d (real (y (4) ),imag (y (4) ) ,-9)
xlabel ('In-Phase');
ylabel ('Quadrature');
title ('Constellation for QPSK')
legend (['message point 1 ( dibit 1 0 ) ' ; ' message point 2 ( dibit 0 0 ) ' ; ' message point 3 (dibit 0 1 ) ' ;
'message point 4 (dibit 1 1 ) '],5)