bshape.asv

16QAM的MATLAB调制解调仿真

function y= bshape (x, fs, fb, N, alfa, delay);
%
% Usge :
%
if nargin<6;  delay=8;   end;
if nargin<5; alfa=.5;    end;
if nargin<4;  N=16;      end;
if nargin<3;  fb=1;      end;
if nargin<2;  fs=16;       end;
if nargin<1; x=pulse  (randint (1,64));   end;
b=firrcos (N, fb, 2*alfa*fb, fs);      
y=filter (b, 1, x); y=y/max (abs (y)); m=fs;
%------------
if nargout<1;
    dt=1/m;t=0:dt;(length (y)-1) *dt;
    subplot (211);plot (t, x, t, y);
    v=axis;axis ( [v (1: 2) v (3) -v (4) *.2 v(4) *1.2]);
    set  (gcf, 'num', ' off',' name',['Baseband Shaping with a Raised Cosine Filter( alfa = ' num2str (alfa) '),' blanks (10) ' BBI 2000']);
  title (' Pulse  Signal');   h=get (gca,' children');
  set (h (1),' color',' b'); set  (h(2),'color', [.9 .8 0]);
  subplot(244);n=length (y);eyescat( y (m: n), fb, fs, delay);
  y=fft (y) /n;y=abs( y(1:fix(n/4))) *2;
  I=find (y<1e-04);y(I) =1e-04;y=20*log10(y);
  x=fft (x) /n;x=abs( x(1:fix(n/4))) *2;
  I=find (x<1e-04);x(I) =1e-04;x=20*log10(x);
  f1=m/n;f=0: f1: (length (y) -1) *f1;
  subplot (223) ; plot(f, x, f, y); h=get (gca,' children');
  set (h (1),' color',' b');set (h (2), ' color' , [.9 .8 0]);
  title(' Power Spectrum');xlabel (' f/fb');zoom xon;
end;