MATLAB CODE FOR QPSK MODULATION TECHNIQUE

MATLAB CODE FOR QPSK MODULATION:

%try cosine wave plot also

%a=.5; 

pi=3.14;

f=1;

x=[0 0 0 1 1 0 1 1 0 0 1 0  1 1 0 1];

nx=size(x,2);

i=1;

while i<nx+1

    t = i:0.001:i+2;

    if x(i)==0 && x(i+1)==0

        z=sin(2*pi*f*t-3*pi/4);

        dibit=0;

    elseif x(i)==0 && x(i+1)==1

        z=sin(2*pi*f*t-pi/4);

        dibit=1;

    elseif x(i)==1 && x(i+1)==0

        z=sin(2*pi*f*t+pi/4);

        dibit=2;

    else

        z=sin(2*pi*f*t+3*pi/4);

        dibit=3;

    end

    %subplot(2,1,1);

    plot(t,dibit,'r');

    %grid on;

    hold on;

    %subplot(2,1,2);

    plot(t,z);

    hold on;

    grid on;

    axis([1 20 -3 3]);

    i=i+2;

end

OUTPUT: 

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