%File : c4_qamdemo.m
levelx=input('Number of D levels >');
levely=input('Number of Q levels >');
m=input('Number of symbol > ');
n=input('Number of samples per symbol >');
bw=input('Filter bandwidth,0<bw<1 > ');%
%
[xd,xq]=qam(levelx,levely,m,n);
%
[b,a]=butter(6,bw);  % determine filter coefficients
yd=filter(b,a,xd);   %filter direct coefficient
yq=filter(b,a,xq);   %filter quadrature coefficient
%
subplot(2,2,1) ;     %first pane
plot(xd,xq,'o');     %unfiltered scatterplot
a=1.4 ;
maxd=max(xd);
maxq=max(xq);
mind=min(xd);
minq=min(xq);
axis([a*mind a*maxd a*minq a*maxq]);
axis equal;
xlabel('xd');ylabel('xq');
%
subplot(2,2,2) ;    %second pane
plot(yd,yq) ;       %filtered scatterplot
axis equal ;
xlabel('xd');ylabel('xq');
%
sym =30 ;               %number of symbol in time plot
nsym=(0:sym*n)/n ;      %x axis vector for time plots
subplot(2,2,3)          %third pane
plot(nsym(1:sym*n),yd(1:sym*n)) ; % filtered direct component
xlabel('symbol index');
ylabel('xd');
%
subplot(2,2,4);         % fourth pane
plot(nsym(1:sym*n),yq(1:sym*n));  %filtered quadrature component
xlabel('symbol index');
ylabel('xq');
%End of script file