matlab 谱峰,MUSIC算法怎么求谱峰对应的角度值
我有个参考的 你研究出来了记得告诉我，我毕设急用
%姓名：吴茜 学号：xxxxxxxxx 08.6.26
%(3)在信噪比变化范围为-20dB－+20dB时，分别采用MUSIC算法,CAPON算法, ESPRIT算法，
% 对上述四个信号源的波达方向进行估计,并画出波达方向估计误差,随着信噪比变化的曲线图
clear all;
clc;
close all;
format short
snr=-20:20; %定义信噪比
snap=2000; %快拍数
n_x=0:snap-1;
M=7; %阵元数
N=4; %信源数
K=0:M-1;
fs=100; %采样率
c=300000000;
lamda=2;
d=lamda/2;
f0=c/lamda ; %目标信号的中心频率
t=[0:snap-1]/fs;
angle=[45,60,30,-45]; %信号方位角
fre=[0.015,0.05,0.02,0.035]; %信号归一化频率
for jj=1:length(snr)
%============产生阵元输出数据矩阵==============
for ii=1:N
S(ii,:)=exp(j*2*pi*(f0*fre(ii)*t+0.5*2^(ii-1)*t.^2));%确保不相干
A(:,ii)=exp(j*pi*K'*sin(angle(ii)/180*pi));
end
x=A*S;
x=awgn(x,snr(jj)); %加高斯白噪声
%=========求阵列接受数据的协方差矩阵R,查看其特征值D===========
R=(x*x')/snap;
[V,D] = eig(R);
%==========music算法============
for i=1:M
DD(i)=D(i,i);
end
[h,e]=sort(DD);
for i=1:M-N
Vn(:,i)=V(:,e(i));
end
theta=-90:0.1:90;
for ii=1:length(theta)
a_theta=exp(j*2*pi*d/lamda*K'*sin(theta(ii)/180*pi));
Pmusic(ii)=10*log10(1/abs(a_theta'*Vn*Vn'*a_theta));
end
estmusic_theta(jj,:)=peak_seek(Pmusic,theta,N);
theta_error_music(jj)=sum(abs(estmusic_theta(jj,:)-sort(angle)))/N; %估计偏差
%=========capon算法===============
L=length(theta);
Pcapon=capon_sp(x,L,d/lamda);
estcapon_theta(jj,:)=peak_seek(Pcapon,theta,N);
theta_error_capon(jj)=sum(abs(estcapon_theta(jj,:)-sort(angle)))/N; %估计偏差
%=========esprit方法=============
est_esprit_theta=transpose(esprit_doa(x,N,d/lamda));
theta_error_esprit(jj)=sum(abs(est_esprit_theta-[-45 60 45 30]))/N; %估计偏差
end
figure(1)
plot(snr,theta_error_music,'r-*');grid on;hold on;
plot(snr,theta_error_capon,'g-o');grid on;hold on;
plot(snr,theta_error_esprit,'-s');grid on;hold on;
title('波达方向估计误差,随着信噪比变化的曲线图');
xlabel('信噪比');
ylabel('估计误差');
legend('music','capon','esprit');
%==============角度搜索程序=============
% 输出前N个峰对应的角度,按角度的从小到大排列
%
% out=peak_seek(pmusic,p_index,N)
%
% pmusic
% p_index
% N
%
%copyright by kily 2008
function out=peak_seek(pmusic,p_index,N)
jj=0;
mm=1;
temp=pmusic(1);
peak=[];
index=[];
for ii=2:length(pmusic)
if temp
jj=1;
else
if jj==1
peak(mm)=temp;
index(mm)=p_index(ii-1);
mm=mm+1;
end
jj=0;
end
temp=pmusic(ii);
end
if length(peak)
[peak,in]=sort(peak);
peak=fliplr(peak);
in=fliplr(in);
for zz=1:length(peak)
out(zz)=index(in(zz));
end
for zz=(length(peak)+1):N
out(zz)=index(in(length(peak)));
end
else
[peak,in]=sort(peak);
peak=fliplr(peak);
in=fliplr(in);
for zz=1:N
out(zz)=index(in(zz));
end
end
[out,mm]=sort(out);