qam.m

个人硕士论文的关于数字接收机调制解调方面的matlab程序

function[y,fs,fb,fc] =qam(x,Kbase,fs,fb,fc);

%Usage:[y,fs,fb,fc] =qam(x,Kbase,fs,fb,fc);   BBI 2000
if nargin<5;fc=2;        end;
if nargin<4;fb=1;        end;
if nargin<3;fs=32;        end;
if nargin<2;Kbase=2;        end;
if nargin<1;
  x=[1 1 1 1 1 1 1 0 1 1 0 1 1 1 0 0];
  x=[x 1 0 1 1 1 0 1 0 1 0 0 1 1 0 0 0];
  x=[x 0 0 1 1 0 0 1 0 0 0 0 1 0 0 0 0];
  x=[x 0 1 1 1 0 1 1 0 0 1 0 1 0 1 0 0];
end;
T=length(x)/fb;   m=fs/fb;   nn=length(x);
dt=1/fs;    t=0:dt:T-dt;
Kbase=rem(Kbase,2);   Kbase=Kbase+(Kbase==0)*2;  tstr='QAM';
I=x(1:2:nn-1);            [I,In]=two2four(I,4*m);
Q=x(2:2:nn);               [Q,Qn]=two2four(Q,4*m);
if Kbase==2;
  I=bshape(I,fs,fb/4);      Q=bshape(Q,fs,fb/4);
end;
y=I.*cos(2*pi*fc*t)-Q.*sin(2*pi*fc*t);y1=y;
n=length(y);

if nargout<1;
  %subplot(211);
  figure(1);
  plot(t,y,[0 T],[0 0],'b:')
    figure(2);
    plot(t,I);
    figure(3);
    plot(t,Q);
  %,t,I,t,Q,[0 T],[0 0],'b:');
    %plot(t,y,t,I,t,Q,[0 T],[0 0],'b:');
  if Kbase==2;
tstr=[tstr 'with the RC filter'];
  end;  title('signal');
  n=length(y);y=fft(y)/n;y=abs(y(1:fix(n/2)))*2;
  I=find(y<1e-04);y(I)=1e-04;y=20*log10(y);
  f1=m/n;f=0:f1:(length(y)-1)*f1;
  figure(4);
  plot(f,y,'r');   grid on;
Title('spectrum');  xlabel('f/fb');  zoom xon;
figure(5);
   constel(y1,fs,fb,fc); xlabel('Constellation');
  set(gcf,'num','off','name',[tstr ',' blanks(10) '曾晶']);
end;

%Start SystemView Definition ---------------
%SVU nInputs=1;
%SVU InputCaption0='In0';
%SVU nOutputs=1;
%SVU OutputCaption0='Out0';
%SVU nParameters=1;
%SVU ParameterCaption0='Param0';
%SVU FunctionSyntax='[Out0] = qam(In0,Param0);';
%End SystemView Definition -----------------