bs.m

空间谱估计中MUSIC算法基于波束空间MUSIC算法

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   空间谱估计中 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clear
close all
clc
%%%%%%%%%%%%%%%%%%%%%%%  generate signal  %%%%%%%%%%%%%%%%%
f0=5000;                      %入射信号频率
fs=1000;                      %采样频率
ts=1/fs;                      %采样间隔
M=8;                           %阵元数
L=100;                        %快拍数
SNR=15;                        %信噪比  %%%%%%                        
the0=[10 40 60];
Q=length(the0);                           %信号源数

c=1500;
lamda=c/f0;
d=lamda/2;                  %c为水下声速，d为阵元间距

t=(1:L)*ts;                 % 采样时刻序列
K=sqrt(2*10^(SNR/10));      %信号的幅度,Pn=1，the load impedance is 1 ohm.

u1=10;
s1=K*exp(j*(2*pi*u1*(t-1)+2*pi*rand(1,L)));
s2=K*exp(j*(2*pi*u1*(t-1)+2*pi*rand(1,L)));
s3=K*exp(j*(2*pi*u1*(t-1)+2*pi*rand(1,L)));  %独立信源

ss=[s1;s2;s3];                  %相干信号源矩阵 基带信号
%%%%%%%%%%%%%%%%%%%%% 生成导向矢量矩阵  %%%%%%%%%%%%%%%%%%%
m=0:M-1;
A=exp(-j*2*pi*m'*d/lamda*sin(the0*pi/180));
%%%%%%%%%%%%%%%%%%%%% 数据协方差矩阵%%%%%%%%%%%       
Nn = wgn(M,L,0,'complex');%  M columns vector of length 100 containing complex white Gaussian noise, each component of which has a noise power of 0 dBW
X=A*ss+Nn;               %阵列接收的相干信号， 情况2                        
R=X*X'/L;               %阵列采样数据协方差矩阵

B=4;
r=0:B-1;
WA=exp(-j*pi*m'*sin(r*2/M));
T1=WA/sqrt(M);
R1=T1'*R*T1;
[V1 D1]=eig(R1);
Un1=V1(:,1:B-Q);   %BS1

v1=ones(M-B+1,1);
T=zeros(M,B);
for r=0:B-1
    T(:,r+1)=[zeros(r,1);v1;zeros(B-1-r,1)];
end
TT=T/sqrt(M-B+1);
T2=orth(TT);
R2=T2'*R*T2;
[V2 D2]=eig(R2);
Un2=V2(:,1:B-Q);   %BS2

v2=ones(M/B,1);
for r=0:B-1
    T(:,r+1)=[zeros(r*M/B,1);v2;zeros((B-1-r)*M/B,1)];
end
T3=T/sqrt(M/B);
R3=T3'*R*T3;
[V3 D3]=eig(R3);
Un3=V3(:,1:B-Q);   %BS3

y1=0;y2=pi/6;y3=pi/3;y4=pi/2;
y=[y1 y2 y3 y4];
C=exp(-j*pi*m'*sin(y));
T5=C*(C'*C)^-0.5;
R5=T5'*R*T5;
[V5 D5]=eig(R5);
Un5=V5(:,2);         %BS5


u=0:0.5:90;                           %搜索范围
for ii=1:length(u)
    Au=exp(-j*2*pi*m'*d/lamda*sin(u(ii)*pi/180));   %搜索范围的导向矢量阵
    P_BS1(ii)=1/abs(Au'*T1*Un1*Un1'*T1'*Au);
    P_BS2(ii)=1/abs(Au'*T2*Un2*Un2'*T2'*Au);
    P_BS3(ii)=1/abs(Au'*T3*Un3*Un3'*T3'*Au);
    P_BS5(ii)=1/abs(Au'*T5*Un5*Un5'*T5'*Au);
    %P(ii)=1/abs(Au'*Un*Un'*Au);
end
plot(u,10*log10(P_BS1),'-r',u,10*log10(P_BS2),'-g',u,10*log10(P_BS3),'--b',u,10*log10(P_BS5),'-k');
legend('BS1','BS2','BS3','BS5'),xlabel('入射角度'),ylabel('空间方位谱(dB)'),
title('波束空间MUSIC'),grid on;