%NC-MUSIC ALGORITHM
%DOA Estimation by ULA
clear all;
close all;
clc
l=0.2; % length of wave
d=0.5*l;
c=1500;% velocity of wave
f0=7500; % center frequency
N=10000; % Length of Signal
M=4; % number of sensor
P=4; % Number of Signals
f1=7510; % signal frequency
f2=7520; %signal frequency
f3=7530; % signal frequency
f4=7540; %signal frequency
fs=15000; % sample frequency
t=0:1/fs:(N-1)/fs;
f=[f1,f2,f3,f4]';
jiao1=-10;
jiao2=-20;
jiao3=5;
jiao4=15;
jiao11=pi*jiao1/180;
jiao22=pi*jiao2/180;
jiao33=pi*jiao3/180;
jiao44=pi*jiao4/180;
jiao=[jiao11 jiao22 jiao33 jiao44 ];
snr1=10;
SNR=[snr1,snr1,snr1,snr1];% signal and noise of ratio
for k0=1:P;
SN(k0)=sqrt(2*10^(SNR(k0)/10));
end
for i=1:P;
for q=1:M
A(i,q)=exp(-j*(q-1)*2*pi*d*sin(jiao(i))/l);
end
end
fai=[30 40 50 60]; % 非圆信号附加相位
Xwei=exp(j*fai);
S=cos(2*pi*f*t);% signal
for k1=1:P;
S(k1,:)=Xwei(k1)*S(k1,:);
end
for k2=1:P;
S1(k2,:)=SN(k2)*S(k2,:);
end
Wn=randn(M,N)+j*randn(M,N); % noise
x=A'*S1+Wn; %加噪声
J=fliplr(eye(M));
X1=x;
X2=J*conj(x);
X=[X1;X2];
RR=X*X';
[V1 D1]=eig(RR);
tezhen1=diag(D1);
[lambda1,index1] = sort((diag(D1)));
Us=V1(:,index1(2*M-P+1:2*M));
J1=[eye(M-1) zeros(M-1,1) zeros(M-1) zeros(M-1,1); zeros(M-1) zeros(M-1,1) eye(M-1) zeros(M-1,1)];
J2=[zeros(M-1,1) eye(M-1) zeros(M-1,1) zeros(M-1); zeros(M-1,1) zeros(M-1) zeros(M-1,1) eye(M-1)];
fai=pinv((J1*Us))*J2*Us;
[Vm,Dm]=eig(fai);
tezhen1=diag(Dm);
estimated_doa1=asin(angle(Dm(1,1))/pi)*180/pi
estimated_doa2=asin(angle(Dm(2,2))/pi)*180/pi
estimated_doa3=asin(angle(Dm(3,3))/pi)*180/pi
estimated_doa4=asin(angle(Dm(4,4))/pi)*180/pi
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