sa_ex7_me.m

Smart antennas for wireless communication - With MATLAB (Gross F.B. - 2005 - McGraw-Hill)

% Maximum Entropy AOA estimation for a M = 6 element array with noise variance = .1
% 
tic
M=6;
sig2=.1;
th1=-5*pi/180;
th2=5*pi/180;
a1=[1];
a2=[1];
a=[1];
u3=[0 0 1 0 0 0];
%for i=2:M
%    a1=[a1 exp(-1j*i*pi*sin(th1))];
%    a2=[a2 exp(-1j*i*pi*sin(th2))];
%end
jk=0:(M-1);
a1=exp(-1j*jk*pi*sin(th1));
a2=exp(-1j*jk*pi*sin(th2));

A=[a1.' a2.'];
Rss=[1 0;0 1];
Rrr=A*Rss*A'+sig2*eye(6);
Sinv=inv(Rrr);
c=Sinv(:,3);
for k=1:360;
   th(k)=-pi/6+pi*k/(3*360);
   clear a
%a=[1];
 %  for jj=2:M
 %     a = [a exp(-1j*jj*pi*sin(th(k)))];
 %  end
 a=exp(-1j*jk*pi*sin(th(k)));
%P(k)=abs(1/(conj(a)*c*c'*a'));
P(k)=abs(1/(a*c*c'*a'));

end
figure;
plot(th*180/pi,10*log10(P/max(P)),'k')
grid on
xlabel('Angle')
ylabel('|P(\theta)|')
axis([-30 30 -30 10])
toc
%num2str(A,2)