%---------------改進(jìn)Music算法-----------------------%
Sensor=8;  Snap=100;          %陣元為8，快拍數(shù)100
Doa=[10 20 50 60];            %要估計(jì)的4個(gè)信源角度
S_number=length(Doa);
Lambda=0.1;                   % 波長(zhǎng)
d=0.5*Lambda;                 % 陣元間距
S_x=[0:Sensor-1]*d; A=exp(-j*2*pi/Lambda*S_x'*sin(Doa*pi/180)); %導(dǎo)向向量
Snr=5; 
Snr=sqrt(10.^(Snr/10));      
%Sig=sqrt(0.5)*(randn(S_number,Snap)+j*randn(S_number,Snap));%全部為非相干信號(hào)情況  
Sig1=sqrt(0.5)*(randn(2,Snap)+j*randn(2,Snap));  %sqrt(0.5)應(yīng)該是歸一化    先產(chǎn)生2個(gè)隨機(jī)信號(hào)
Sig2=Sig1+(10+10j);           %產(chǎn)生相干信號(hào)
Sig=cat(1,Sig1,Sig2);         %總信號(hào)表達(dá)式
Noise=sqrt(0.5)*(randn(Sensor,Snap)+j*randn(Sensor,Snap));  % 噪聲  
X=Snr*A*Sig+Noise;            %接收數(shù)據(jù)矩陣
R=X*X'/Snap;                  %接收數(shù)據(jù)協(xié)方差矩
J=eye(Sensor);                %單位矩陣
J=rot90(J);                   %旋轉(zhuǎn)過(guò)后--交換矩陣
R1=R';
R1=R1.';
RB=J*R1*J;
RFB=0.5*(R+RB);               %總的協(xié)方差矩陣
[U S V]=svd(RFB);             %奇異值分解
En=U(:,S_number+1:Sensor);    %噪聲子空間
theta=[-90:0.1:90]*pi/180;    %搜索步進(jìn)
for num=1:length(theta)
    A_search=exp(-j*2*pi/Lambda*S_x'*sin(theta(num)));
    P_music(num)=abs(1/(A_search'*En*En'*A_search));   %譜函數(shù)
end
%---------------繪圖-----------------------%
h=[-90:0.1:90];
% plot(h,10*log10(P_music));
plot(h,10*log10(P_music/max(P_music)));
axis([-100 100 -50 +10])
xlabel('Angle(degree)','fontsize',10)
ylabel('Pmusic','fontsize',10)
title('改進(jìn) Music');
grid