constel.m

对ASK调制解调进行了仿真,包括程序仿真和模型仿真

function c=constel(x,fs,fb,fc);
if nargin<4; fc=2; end;
if nargin<3; fb=1; end;
if nargin<2; fs=32; end;
if nargin<1; 
    t=(0:255)/fs; x=cos(2*pi*fc*t+.25*pi);
end;
N=length(x); m=2*fs/fb; n=fs/fc;
i1=m-n; i=1; ph0=(i1-1)*2*pi/n;
while i<=N/m;
    xi=x(i1:i1+n-1); y=2*fft(xi)/n; c(i)=y(2);
    i=i+1; i1=i1+m;
end;
if nargout<1;
    cmax=max(abs(c));
    ph=(0:5:360)*pi/180;plot(1.414*cos(ph),1.414*sin(ph), 'c');
    hold on;
    for i=1:length(c);
        ph=angle(c(i))-ph0+pi;
        a=abs(c(i))/cmax*1.414;
        plot(a*cos(ph),a*sin(ph),'r*');
    end;
    plot([-1.5 1.5],[0 0], 'k:', [0 0],[-1.5 1.5], 'k:');
    hold off; axis equal; axis ([-1.5 1.5  -1.5 1.5]);
end;