prob3_7.m

these m files contain the solution of some problems in the book "communication system" by Haykin

%Prob. 3.6
%part (d) and (e)
%Yao Wang 2/28/2000

%CSFT
clear all
fm=0;
for (f1=-1:0.01:1)       
   fm=fm+1;fn=0;
   for (f2=-1:0.01:1)
	fn=fn+1;
   psi_c(fm,fn)=sqrt(2*pi)*exp(-2*pi*pi*(f1*f1+f2*f2));
end;
end;
figure(1);
surf(-1:0.01:1,-1:0.01:1,psi_c);

figure(2);
imagesc(-1:0.01:1,-1:0.01:1,psi_c);
colormap(gray(256));


%SSFT
clear all;
alpha=1.43;
fm=0;
for (f1=-1:0.01:1)       
   fm=fm+1;fn=0;
   for (f2=-1:0.01:1)
      fn=fn+1;
      psi_s(fm,fn)=0;
      for (m=-5:1:5)
         for (n=-5:1:5)
            psi_s(fm,fn)=psi_s(fm,fn)+....
               4*pi/sqrt(3)/alpha*exp(-2*pi*pi*...
               ((f1-(2*m-n)/1.732/alpha)^2+(f2-n/alpha)^2));
         end;
      end;
   end;
end;

figure(3);
surf(-1:0.01:1,-1:0.01:1,psi_s);

figure(4);
imagesc(-1:0.01:1,-1:0.01:1,psi_s);
colormap(gray(256));


%DSFT
clear all;
alpha=1.43;
fm=0;
for (f1=-1:0.01:1)       
   fm=fm+1;fn=0;
   for (f2=-1:0.01:1)
      fn=fn+1;
      psi_d(fm,fn)=0;
      for (m=-2:1:2)
         for (n=-2:1:2)
            psi_d(fm,fn)=psi_d(fm,fn)+....
               4*pi/sqrt(3)/alpha*exp(-2*pi*pi*...
               ((2/1.732/alpha*(f1-m)-1/1.732/alpha*(f2-n))^2+(1/alpha*(f2-n))^2));
         end;
      end;
   end;
end;

figure(5);
surf(-1:0.01:1,-1:0.01:1,psi_d);

figure(6);
imagesc(-1:0.01:1,-1:0.01:1,psi_d);
colormap(gray(256));