1 简介
基于非相干信号子空间测向算法实现宽带信号的测向
2 完整代码
%[1]宫兵, 徐以涛, 李佳. 改进的非相干信号子空间宽带测向算法[J]. 无线电工程, 2011, 41(3):3.
clc
clear all
close all
M=8; %阵元数
N=33; %快拍数
ts=0.0125; %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=5; %信噪比
b=pi/180;
theat1=12*b; %入射信号波束角1
theat2=8*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);
sa=fft(s1,2048);
figure,
specgram(s1,256,1E3,256,250); % Display the spectrogramsa=fft(s1,2048); %进行FFT变换
s2=chirp(n+0.125,80,1,120); %生成线形调频信号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=1:33
f=80+(i-1)*1.25;
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
3 仿真结果
4 参考文献
[1]宫兵, 徐以涛, 李佳. 改进的非相干信号子空间宽带测向算法[J]. 无线电工程, 2011, 41(3):3.