doa_estimation line.m

智能天线中多单元线形天线阵的波达方向估计

%七单元线形天线阵的波达方向估计
d    = .5;     %天线阵元的归一化间距
N    = 8;      %number of sensors
M    = 4;      %source number
K    = 100;    %snapshot
theta = [30 60 120 160];
Ps = 1; %signal power
SNR = 30; %signal to noise ratio
St = randn(M,K)+j*randn(M,K);
St = sqrt(Ps)*St;
Nt = randn(N,K)+j*randn(N,K);
Pn = Ps/(10^(SNR/10));
Nt = sqrt(Pn)*Nt;
Xt = zeros(N,K);
for m = 1:M
    thetam = theta(m)*pi/180;
    am     = exp(j*pi*d*[0:N-1]'*cos(thetam));
    Xt     = Xt+am*St(m,:);
end
Xt = Xt+Nt;

Rx = Xt*Xt'/K;
[a,b,c] = svd(Rx);
Un      = a(:,M+1:N);

thetat = 0:180;
for n = 1:length(thetat)
    thetan    = thetat(n)*pi/180;
    an        = exp(j*pi*d*[0:N-1]'*cos(thetan));
    S_ca(n)   = abs(1/(an'*inv(Rx)*an));
    S_mu(n)   = abs(1/(an'*Un*Un'*an));
end
S_ca = S_ca/max(S_ca);
S_mu = S_mu/max(S_mu);

plot(thetat,10*log10(S_ca),'b');
hold on
plot(thetat,10*log10(S_mu),'r');
xlabel('方位角');
ylabel('空间谱(对数坐标)');
grid on;