aepmethod3.m

空时自适应信号处理

%%电子学报（基于杂波协方差矩阵特征向量分析的STAP降维方法）
clc;clear all;close all;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
N= 8;                      % number of sensors
M= 8;                      % number of pulse
lamda=0.03;               % wavelength
V_p=90;                    % platform velocity
d=0.015;                   % spacing of sensors
PRF=12000;                 % pulse repetition frequency
T=1/PRF;                   % pulse repetition interval
H=500;                     % platform height    
R=1000;                    % range
theta=asin(H/R);           % depression angle
Bc=0;                      % clutter bandwidth
mm=0:1:N-1;mm=mm';
nn=0:1:M-1;nn=nn';
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%V_d=20;
%fai_darget=pi/2;
%Wd_d=4*pi*V_d*cos(fai_darget)/(lamda*PRF);         %目标多普勒角频率
%Ws_d=2*pi*d*cos(fai_darget)/lamda;                 %目标空间角频率
%bM_d=exp(j*Wd_d*mm);                                %M×1目标维时间导向矢量
%aN_d=exp(j*Ws_d*nn);                                %N×1目标维空间导向矢量
%S_d=kron(bM_d,aN_d); 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% %Clutter Covariance Matrix% %%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for m=1:1:M
    for p=1:1:M
        for i=1:1:N
            for k=1:1:N
                l=(m-1)*N+i;
                n=(p-1)*N+k;
                phi=linspace(0,2*pi,61);
                %D=0.5*(1+cos(2*(phi-pi/2)));
                %D=D.^2;                
                                
                D=1;% 有无加权影响很大！
                G=1;                    
                t_phase=exp(j*2*pi/lamda*2*V_p*(m-p)*T*cos(phi));
                s_phase=exp(j*2*pi/lamda*(i-k)      *d*cos(phi));
                integral=D.*t_phase.*s_phase.*G;
                
                Q(l,n)=sum(integral)/60;
               % Q(l,n)=Q(l,n)*exp(-Bc*Bc*(m-p)^2/8);
            end
        end
    end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CNR=trace(Q)/trace(0.01*eye(N*M,N*M))
Q=Q+0.00001*eye(N*M,N*M);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
fd_d=0;
AA=exp(j*2*pi*nn);
BB=exp(j*2*pi*mm*fd_d);
S_d=kron(AA,BB);         %search channel
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%特征分解AEP
Q_tr=trace(Q);           %
Q_inv=inv(Q);            %
Q_d=eig(Q);
Q_d=flipud(Q_d);
%[V,D] = eig(Q,'nobalance')
[V,D]=eig(Q);            %对杂波协方差矩阵进行特征分解
for i3=1:M*N
    V(:,i3)=V(:,M*N-i3+1);
    D(i3,i3)=D(M*N-i3+1,M*N-i3+1);
end
%T_c=V(:,1:15);          %auxiliary channel
%TT=[S_d,T_c];           %transform matrix
K=16;
TT=zeros(M*N,K);
for i1=1:K-1
    TT(i1,i1)=(1/Q_d(i1,1))*V(:,i1)'*S_d;
end
for i2=K:M*N
    TT(i2,K)=(1/Q_d(i2,1))*V(:,i2)'*S_d;
end

TT1=V*TT;
QT=TT'*Q*TT;
QT_inv=inv(QT);
%% IF %%
ii=1;
for fd=-0.5:0.01:0.5
    
    AAi=exp(j*2*pi*nn);
    BBi=exp(j*2*pi*mm*fd);
    S=kron(BBi,AAi);
    IFopt(ii)=S'*Q_inv*S*Q_tr/(S'*S);
    ST=TT'*S;
    WT=QT_inv*ST;
    IFaep(ii)=(WT'*ST*ST'*WT*Q_tr)/((WT'*QT*WT)*(S'*S));
    %SINR2(ii)=abs((QT_inv*ST)'*ST);
    ii=ii+1;
end
IFopt=20*log10(IFopt/max(IFopt));
IFaep=20*log10(IFaep/max(IFaep));    
    
figure(1);
mesh(abs(Q));title('Modulus');

figure(2);
fd=-0.5:0.01:0.5;
plot(fd,IFopt,'-b');
hold on;
plot(fd,IFaep,'r');