matlab_实现预警雷达最优stap的仿真，阵列天线模型，脉冲发射雷达

%opt2d.m: 全自由度空时自适应处理 %-------------------------------------------------------------------------- %start : 2004.11.04 AM 10:21 yunrisheng %Latest change : %-------------------------------------------------------------------------- clear tic %杂波仿真参数 N = 12; % 阵元个数 M = 10; % 相干脉冲数 CNR = 30; % 杂噪比 beta = 1; % 杂波折叠系数(beta = 2*v*T/d) sita_a = -90:.9:90.; % 杂波单元个数 sita = sita_a*pi/180; [NN N_bin] = size(sita); %目标参数 sita_t = -25; % 目标DOA omiga_t = 0.4; % 目标Doppler SNR = 0; % 信噪比 %空间导向矢量和时间导向矢量 %空间频率和Dopple频率满足 omiga_d = beta * omiga_s omiga_s = pi*sin(sita); omiga_d = beta*omiga_s; aN = zeros(N,N_bin); bN = zeros(M,N_bin); aN = exp(-j*[0:N-1]'*omiga_s)./sqrt(N); bN = exp(-j*[0:M-1]'*omiga_d)./sqrt(M); %目标空时信号 aN_t = zeros(N,1); bN_t = zeros(M,1); aN_t = exp(-j*pi*[0:N-1]'*sin(sita_t*pi/180))/sqrt(N); bN_t = exp(-j*pi*[0:M-1]'*omiga_t)/sqrt(M); S_t = zeros(M*N,1); S_t = kron(aN_t,bN_t); %计算杂波协方差矩阵 R = zeros(M*N,M*N); S = zeros(M*N,N_bin); ksai = 10^(CNR/10)*(randn(1,N_bin)+j*randn(1,N_bin))/sqrt(2); %服从正态分布的随机幅值，方差为1 for ii = 1:N_bin S(:,ii) = kron(aN(:,ii),bN(:,ii)); R = R + ksai(ii).*(S(:,ii)*S(:,ii)'); end %干扰协方差矩阵，杂噪比为30dB R = R +eye(M*N); %CNR = 30dB inv_R = inv(R); %逆矩阵 %求特征值谱 [u s v] = svd(R); %特征值分解 figure(1); plot(10*log10(diag(s))); title('阵元数N=12, 相干脉冲数M=10'); axis([0 120 -10 50]); xlabel('特征值数目'); ylabel('特征值(dB)'); grid on P_f = zeros(N_bin,N_bin); P_min_var = zeros(N_bin,N_bin); %求杂波谱 for ii = 1:N_bin for jj = 1:N_bin SS = kron(aN(:,ii),bN(:,jj)); P_f(ii,jj) = SS'*R*SS; %傅氏谱 P_min_var(ii,jj) = 1./(SS'*inv_R*SS); end end %最小方差功率谱 figure(2) mesh(sin(sita),omiga_d/pi,20*log10(abs(P_min_var))); title('阵元数N=12, 相干脉冲数M=10'); xlabel('方位余弦'); ylabel('归一化Dopple频率'); zlabel('功率(dB)'); grid on %空时最优权向量 w_opt = inv(R)*S_t./(S_t'*inv_R*S_t); %w_opt = inv(RR)*a_t; %求最优空时响应 for ii = 1:N_bin for jj = 1:N_bin SSS = kron(aN(:,ii),bN(:,jj)); res_opt(ii,jj) = SSS'*w_opt; end end figure(3) %[X,Y]=meshgrid(omiga_d/pi,sita_a); mesh(omiga_d/pi,omiga_d/pi,10*log10(abs(res_opt).^2)) title('阵元数N=12, 相干脉冲数M=10'); xlabel('归一化opple频率'); ylabel('方位余弦'); zlabel('功率(dB)'); grid on %求最优改善因子 for ii = 1:N_bin for jj = 1:N_bin SS = kron(aN(:,ii),bN(:,jj)); % IF(ii,jj) = SS'*inv_R*SS.*trace(R)./(SS'*SS); IF(ii,jj) = SS'*inv_R*SS./(SS'*SS); end end figure(4) axis([-1 1 10 55]); plot(omiga_d/pi,10*log10(abs(IF(101,:)))); xlabel('归一化opple频率'); ylabel('改善因子(dB)'); grid on toc