MATLAB/QPSK.m at master · Tarasis6/MATLAB · GitHub

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close all;
clear all

N = 16384;
m  = 2;
Br = 16;
Fs = 256;
f0 = 32;
beta = 0.3;
t = [0 : Fs / Br * N - 1]' / Fs;

data = randi(2,N,m)-1;
table_qpsk = [1 + 1i,1 - 1i,-1 + 1i, -1 - 1i];
IQ  = table_qpsk(bi2de(data) + 1);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

IQf = [IQ;zeros(Fs/Br-1,length(IQ))];
IQf = reshape(IQf,[],1);
IQ = repmat(IQ,Fs/Br,1);
IQ = reshape(IQ,[],1);

b = rcosdesign(beta,4,Fs/Br,'normal') / 4;
IQf = conv(IQf,b,'same');
Sf = real(IQf) .* cos(2 * pi * f0 * t) - imag(IQf) .* sin(2 * pi * f0 * t);

S = real(IQ) .* cos(2 * pi * f0 * t) - imag(IQ) .* sin(2 * pi * f0 * t);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
figure
subplot(2,1,1)
plot(t(1:Fs/Br*8-1),S(1:Fs/Br*8-1));
hold on;
plot(t(1:Fs/Br*8-1),real(IQ(1:Fs/Br*8-1)),'r');
plot(t(1:Fs/Br*8-1),imag(IQ(1:Fs/Br*8-1)),'g');
hold off;

subplot(2,1,2)
plot(t(1:Fs/Br*8-1),Sf(1:Fs/Br*8-1));
hold on;
plot(t(1:Fs/Br*8-1),real(IQf(1:Fs/Br*8-1)),'r');
plot(t(1:Fs/Br*8-1),imag(IQf(1:Fs/Br*8-1)),'g');
hold off;

figure
subplot(1,2,1)
plot(real(IQ),imag(IQ));
axis([-2,2,-2,2]);
subplot(1,2,2)
plot(real(IQf*Fs/Br),imag(IQf*Fs/Br));
axis([-2,2,-2,2]);

figure
%***********************************************************************
ff = [-length(S) / 2 : length(S) / 2 - 1 ] * Fs / length(S); %ï³äïèñ îñ³
%***********************************************************************
Spec = fftshift(fft(IQ));
Specf = fftshift(fft(IQf));
subplot(1,2,1)
plot(ff,abs(Spec));
subplot(1,2,2)
plot(ff,abs(Specf));

figure
Spec = fftshift(fft(S));
Specf = fftshift(fft(Sf));
subplot(1,2,1)
plot(ff,abs(Spec));
subplot(1,2,2)
plot(ff,abs(Specf));
%=======================================================================


figure
plot(real(IQf*Fs/Br),'r');
hold on;
plot(imag(IQf*Fs/Br),'g');

plot(real(IQ),'r');
plot(imag(IQ),'g');

axis([0,150,-1.5,1.5]);

hold off;

%*************** GLAS diagram   *************************
IQ_eye = reshape(IQf,4 * Fs/Br,[]);
figure
plot(real(IQ_eye));