qpskd.m

来自「quadrature phase shift keying demodulati」· M 代码 · 共 41 行

function qpskd(g,f)
%Modulation  QPSK
%Example: g is a binay vector; f is the carrier frequency. 
%qpskd([1 0 1 1 0 0],2)
t=0:2*pi/99:2*pi;
cp=[];sp=[];
mod=[];mod1=[];bit=[];
for n=1:2:length(g);
    if g(n)==0 && g(n+1)==1;
        die=sqrt(2)/2*ones(1,100);
        die1=-sqrt(2)/2*ones(1,100);
        se=[zeros(1,50) ones(1,50)];
    elseif g(n)==0 && g(n+1)==0;
        die=-sqrt(2)/2*ones(1,100);
        die1=-sqrt(2)/2*ones(1,100);
        se=[zeros(1,50) zeros(1,50)];
    elseif g(n)==1 && g(n+1)==0;
        die=-sqrt(2)/2*ones(1,100);
        die1=sqrt(2)/2*ones(1,100);
        se=[ones(1,50) zeros(1,50)];
    elseif g(n)==1 && g(n+1)==1;
        die=sqrt(2)/2*ones(1,100);
        die1=sqrt(2)/2*ones(1,100);
        se=[ones(1,50) ones(1,50)];
    end
    c=cos(f*t);
    s=sin(f*t);
    cp=[cp die];    %Amplitude cosino
    sp=[sp die1];   %Amplitude sino
    mod=[mod c];    %cosino carrier (Q)
    mod1=[mod1 s];  %sino carrier   (I)
    bit=[bit se];
end
bpsk=cp.*mod+sp.*mod1;
subplot(2,1,1);plot(bit,'LineWidth',1.5);grid on;
title('Binary Signal')
axis([0 50*length(g) -1.5 1.5]);

subplot(2,1,2);plot(bpsk,'LineWidth',1.5);grid on;
title('QPSK modulation')
axis([0 50*length(g) -1.5 1.5]);