qam4_10.m

QAM信号

clear all;
%function y=QAM_4(fs,bits)
bits=randint(800,1,2);
fs=8e7;
rb=1e6;
fc=1e7;
fa=1e5;
nb=length(bits);
ns=ceil(nb/2);
b0=zeros(1,ns*2);
b0(1:nb)=bits;
IR=[-1 1];
t=[0:79]; 
for s=1:400
     ba=b0(((s-1)*2)+1);
    bb=b0(((s-1)*2)+2);
    R=IR(ba+1);
    I=IR(bb+1);
    r(s)=R+j*I;
   % y1(s)=abs(r(s));  
end
[ys,ts] = rcosine(rb,fs,'fir/sqrt',1.0);
[yc,tc] = rcosflt(r,rb,fs,'filter',ys);
yc=abs(yc(201:32200));
for s=1:ns
    for t=1:80
      y((s-1)*80+t)= yc((s-1)*80+t)*cos(2*pi*fc*t/fs+angle(r(s)));
    end
end
signal=awgn( y,5,'measured',[],'db');  
%yc=yc(25:16024);
%for i=1:16000
   % signal(i)=signal(i)*yc(i);
%end
%figure;
%plot(r(20:40:32000),'.');
%axis([-2 2 -2 2]);
%Y=fft(y);
%ts=(0:length(Y)-1)*fc/length(Y);
%figure;
%plot(ts,abs(Y));
 %semilogy(ts,abs(Y));
 %axis([1 10e4 1 1e4]);
long=8;