%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   空間譜估計中 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%clearclose allclc%%%%%%%%%%%%%%%%%%%%%%%  generate signal  %%%%%%%%%%%%%%%%%f0=5000;                      %入射信號頻率fs=1000;                      %采樣頻率ts=1/fs;                      %采樣間隔M=8;                           %陣元數L=100;                        %快拍數SNR=20;                        %信噪比  %%%%%%                        the0=[-10 20];Q=length(the0);                           %信號源數c=1500;lamda=c/f0;d=lamda/2;                  %c為水下聲速，d為陣元間距t=(1:L)*ts;                 % 采樣時刻序列K=sqrt(2*10^(SNR/10));      %信號的幅度,Pn=1，the load impedance is 1 ohm.u1=10;s1=K*exp(j*(2*pi*u1*(t-1)+pi/6));s2=K*exp(j*(2*pi*u1*(t-1)+pi/3));     % s3=K*exp(j*(2*pi*u1*(t-1)+pi/2));   %相干信源ss=[s1;s2]%;s3];                  %相干信號源矩陣 基帶信號%%%%%%%%%%%%%%%%%%%%% 生成導向矢量矩陣  %%%%%%%%%%%%%%%%%%%m=0:M-1;A=exp(-j*2*pi*m'*d/lamda*sin(the0*pi/180));%%%%%%%%%%%%%%%%%%%%% 數據協方差矩陣%%%%%%%%%%%       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 dBWX=A*ss+Nn;               %陣列接收的相干信號， 情況2                        R=X*X'/L;               %陣列采樣數據協方差矩陣[U S V]=svd(R);e=U(:,1);       %最大特征值對應的特征矢量x=X*X(1,:)'/L;  %數據矢量%%%%%%%%%%%%%%%%%%%  構造矩陣Y  %%%%%%%%%%%%%%%%%%%mm=4;p=5;Y=zeros(mm,p);for k=1:p    Y1(:,k)=e(k:k+mm-1);    Y2(:,k)=x(k:k+mm-1);end%%%%%%%%%%%% 解相干后的噪聲子空間 %%%%%%%%%%%%%%%%[U1 S1 V1]=svd(Y1);Un1=U1(:,Q+1:mm);[U2 S2 V2]=svd(Y2);Un2=U2(:,Q+1:mm);%%%%%%%%%%%  基于矢量奇異值算法的MUSIC %%%%%%%%%%%%%%%%%%%%u=-90:0.5:90;                           %搜索范圍for ii=1:length(u)    Au=exp(-j*2*pi*m'*d/lamda*sin(u(ii)*pi/180));   %搜索范圍的導向矢量陣    P_esvd(ii)=1/abs(Au(1:mm)'*Un1*Un1'*Au(1:mm));    P_dsvd(ii)=1/abs(Au(1:mm)'*Un2*Un2'*Au(1:mm));    endplot(u,10*log10(P_esvd),'s-r',u,10*log10(P_dsvd),'x-g')%,u,10*log10(Pfb),'--b',u,10*log10(P),'-k');legend('ESVD','DSVD,'),xlabel('入射角度'),ylabel('空間方位譜(dB)'),title('矢量奇異值算法'),grid on;%mm=4,p=5%Q=3時， (1)[-5 0 5]無法完全分辨 ， 直至(2)[-10 0 10]才能有誤差的分辨，  至(3)[-13 0 13]能無誤差地分辨%Q=2時，(1)[0 5]剛好能分辨 ，(2)[-10 20]