%%% DOA estimation by spatial smoothing or modified spatial smoothing
% Developed by xiaofei zhang (南京航空航天大学 电子工程系 张小飞）
% EMAIL:zhangxiaofei@nuaa.edu.cn
clear all
close all
derad = pi/180; % deg -> rad
radeg = 180/pi;
twpi = 2*pi;
Melm = 7;
kelm = 6;
dd = 0.5;
d=0:dd:(Melm-1)*dd;
iwave = 3;
theta = [0 30 60];
n = 200 %
A=exp(-j*twpi*d.'*sin(theta*derad));%%%% direction matrix
S0=randn(iwave-1,n);
S=[S0(1,:);S0];
X0=A*S;
X=awgn(X0,10,'measured');
Rxxm=X*X'/n;
issp = 1;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% spatial smoothing music
if issp == 1
Rxx = ssp(Rxxm,kelm);
elseif issp == 2
Rxx = mssp(Rxxm,kelm);
else
Rxx = Rxxm;
kelm = Melm;
end
% Rxx
[EV,D]=eig(Rxx);
EVA=diag(D)'; [EVA,I]=sort(EVA);
EVA=fliplr(EVA), EV=fliplr(EV(:,I));
for iang = 1:361
angle(iang)=(iang-181)/2;
phim=derad*angle(iang);
a=exp(-j*twpi*d(1:kelm)*sin(phim)).';
L=iwave;
En=EV(:,L+1:kelm);
SP(iang)=(a'*a)/(a'*En*En'*a);
end
SP=abs(SP);
SPmax=max(SP);
SP=10*log10(SP/SPmax);
%SP=SP/SPmax;
figure
h=plot(angle,SP);
set(h,'Linewidth',2)
xlabel('angle (degree)')
ylabel('magnitude (dB)')
axis([-90 90 -60 0])
set(gca, 'XTick',[-90:30:90], 'YTick',[-60:10:0])
grid on
hold on
legend('平滑MUSIC')
