ISM_code_宽带信号DOA_宽带信号DOA_宽带DOA_宽带ISM_ISM

%宽带信号DOA估计算法：非相干信号子空间（ISM）算法 % 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 clc clear all close all M=12; %阵元数 N=200; %快拍数 ts=0.01; %时域采样间隔 f0=100; %入射信号中心频率 f1=80; %入射信号最低频率 f2=120; %入射信号最高频率 c=1500; %声速 lambda=c/f0; %波长 d=lambda/2; %阵元间距 SNR=15; %信噪比 b=pi/180; theat1=30*b; %入射信号波束角1 theat2=0*b; %入射信号波束角2 n=ts:ts:N*ts; theat=[theat1 theat2]'; %%%%%%%%%%%%%%%% produce signal %%%%%%%%%%%%%%%% s1=chirp(n,80,1,120); %生成线性调频信号1； sa=fft(s1,2048); %进行FFT变换 %figure, %specgram(s1,256,1E3,256,250); %频谱图 s2=chirp(n+0.100,80,1,120); %生成线性调频信号2 sb=fft(s2,2048); %进行FFT变换 % %%%%%%%%%%%%%%%%%%%%% ISM算法 %%%%%%%%%%%%%%%%%% P=1:2; a=zeros(M,2); sump=zeros(1,181); for i=1:N f=80+(i-1)*1.0; s=[sa(i) sb(i)]'; for m=1:M a(m,P)=exp(-j*2*pi*f*d/c*sin(theat(P))*(m-1))'; end R=a*(s*s')*a'; [em,zm]=eig(R); [zm1,pos1]=max(zm); for l=1:2 [zm2,pos2]=max(zm1); zm1(:,pos2)=[]; em(:,pos2)=[]; end k=1; for ii=-90:1:90 arfa=sin(ii*b)*d/c; for iii=1:M tao(1,iii)=(iii-1)*arfa; end A=[exp(-j*2*pi*f*tao)]'; p(k)=A'*em*em'*A; k=k+1; end sump=sump+abs(p); end pmusic=1/33*sump; pm=1./pmusic; thetaesti=-90:1:90; plot(thetaesti,20*log(abs(pm))); xlabel('入射角/度'); ylabel('空间谱/dB'); grid on