squint_sar.rar_SAR_matlab，目标_SAR，斜视_doppler sar_sar squint_距离多普勒

clear all close all %% cj=sqrt(-1); c=3e8; pi2=2*pi; %天线参数 theta=15;%斜视角 theta=theta*pi/180; lambda=0.03;%载频波长 La=2.5;%5;%天线方位向口径 beta=0.886*lambda/La; %发散角 %%测绘带 Xc=1e3;%41.65e3; Yc=Xc*tan(theta);%方位向中心 Wr=200; Wa=200; %%距离向参数 fc=c/lambda; wc=pi2*fc; Tp=1.667e-6;%脉冲持续时间 Br=60e6;%带宽 Kr=Br/Tp; fcm=fc-Kr*Tp; wcm=fcm*pi2; Fs=2.2*Br;%快时间采样率 dt=1/Fs;%快时间采样间隔 Rn=(Xc-Wr/2)/cos(theta-beta/2);%场景最近斜距 Rf=(Xc+Wr/2)/cos(theta+beta/2);%场景最远斜距 % T=2*(Rf-Rn)/c+Tp; % Nr=ceil((2*(Rf-Rn)/c+Tp)*Fs);%距离向采样点个数 Ts=2*Rn/c;%距离向采样起始时间 Tf=2*Rf/c+Tp;%距离向采样截止时间 T=Tf-Ts; Ts=Ts-.1*T; Tf=Tf+.1*T; T=Tf-Ts; Nr=ceil(T*Fs); t=Ts+dt*(0:Nr-1);%快时间采样序列； df=Fs/Nr; f=df*(-Nr/2:Nr/2-1); %%方位向参数 Vr=250;%载机速度 PRF=1000; dtao=1/PRF;%方位向采样间隔 Tas=-((Xc+Wr)*tan(theta+beta/2)-(Yc-Wa/2))/Vr; %方位向采样起始时刻 Tae=((Yc+Wa/2)-(Xc-Wr/2)*tan(theta-beta/2))/Vr;%方位向采样结束时刻 % Tae=(Wr/2*tan(theta-beta/2)+Wa/2+Xc*(tan(theta)-tan(theta-beta/2))); Ta=Tas-Tae; Tas=Tas-.1*Ta; Tae=Tae+.1*Ta; Ta=Tae-Tas; Na=ceil(1.2*Ta*PRF); tao=dtao*(-Na/2:Na/2-1);%慢时间采样序列 Ar=-2; u=Vr*tao+.5*Ar.*(tao.^2); du=Vr*dtao; dfu=PRF/Na; fu=dfu*(-Na/2:Na/2-1); Ka=-2*((Vr*cos(theta))^2)/lambda/Xc; fdc=2*Vr*sin(theta)/lambda; % tao1=Tas+(0:Na-1)*dtao; Tao=ones(Nr,1)*tao; U=ones(Nr,1)*u; FU=ones(Nr,1)*fu; FU1=FU-fdc; T=t(:)*ones(1,Na); F=f(:)*ones(1,Na); %%%实际物理尺寸 x=Xc+dt*(-Nr/2:Nr/2-1)*c/2; y=du*cos(theta)*(-Na/2:Na/2-1); %%目标区域 % Ntar=3; % Xn=zeros(1,Ntar);Yn=zeros(1,Ntar); % Xn(1)=Xc; Yn(1)=Yc; % Xn(2)=Xc-.5*Wr/2;Yn(2)=Yc-.5*Wa/2; % Xn(3)=Xc+.5*Wr/2;Yn(3)=Yc-.5*Wa/2; P=50*du;%%P=100*du;可以看到条纹 dyn=du*5; dxn=2.5; nx=100; % ny=10; ny=2; ntarget=nx*ny; Xn=zeros(nx,ny);Yn=zeros(nx,ny);fn=ones(nx,ny); % xn_o=(-ny/2*dx*0.5:0.5*dx:(ny/2-1)*0.5*dx); % xn_o=0; % Xn=ones(nx,1)*xn_o+Xc; % yn_o(1:nx/4)=(-nx/4*dy*5:5*dy:(-1)*dy*5)-50+Yc; % yn_o(nx/4+1:nx/2)=(-nx/4*dy*5:5*dy:(-1)*dy*5)+Yc; % yn_o(nx/2+1:nx*3/4)=(-nx/4*dy*5:5*dy:(-1)*dy*5)+50+Yc; % yn_o(nx*3/4+1:nx)=(-nx/4*dy*5:5*dy:(-1)*dy*5)+100+Yc; % Yn=yn_o(:)*ones(1,ny); % a=nx; % b=ny; xn_o=0; xn_o=(-ny/2*dxn*0.5:0.5*dxn:(ny/2-1)*0.5*dxn); Xn=ones(nx,1)*xn_o+Xc; yn_o(1:nx)=(-nx/2*dyn:dyn:(nx/2-1)*dyn); Yn=yn_o(:)*ones(1,ny)+Yc; a=nx; b=ny; %%回波模拟 so=zeros(Nr,Na); so2=zeros(Nr,Na); for i=1:a; i for j=1:b; j Uci=((Yn(i,j)-Yc)-(Xn(i,j)-Xc)*tan(theta));%第i个目标方位向中心时刻 Rci=Xn(i,j)/cos(theta);%点目标中心斜距 Usi=Rci*(cos(theta)*tan(theta+beta/2)-sin(theta));% 目标方位向采样起始时刻 Uei=Rci*(sin(theta)-cos(theta)*tan(theta-beta/2));%目标方位向采样结束时刻 R=sqrt(Xn(i,j)^2+(Yn(i,j)-U).^2);%雷达和目标之间的瞬时斜距 DT=T-2*R/c; phase=pi*Kr*(DT.^2)-4*pi*R/lambda; sn=exp(cj*phase).*(DT >=0 & DT <=Tp).*(U >= (Uci-Usi) & U <= (Uci+Uei)); so=so+sn; R2=sqrt(Xn(i,j)^2+(Yn(i,j)-U-P).^2); DT2=T-2*R2/c; phase2=pi*Kr*(DT2.^2)-4*pi*R2/lambda; sn2=exp(cj*phase2).*(DT2 >=0 & DT2 <=Tp).*((U+P) >= (Uci-Usi) & (U+P) <= (Uci+Uei)); so2=so2+sn2; end end; figure(1) imagesc(real(so)); axis square;axis xy; title('原始接收信号'); %%%%%%%%%%%%%%距离向匹配滤波 Rc=sqrt(Xc^2+Yc^2); tr=T-2*sqrt(Xc^2+Yc^2)/c; sr=exp(cj*pi*Kr*(tr).^2).*(tr >= 0 & tr <= Tp); Nsr=300; % winr=[zeros((Nr-Nsr)/2,1);hanning(Nsr);zeros((Nr-Nsr)/2,1)]; winr=hanning(Nr); winr=winr*ones(1,Na); sr=sr.*winr; SR=ftx(sr); S=ftx(so).*conj(SR); s=iftx(S); S2=ftx(so2).*conj(SR); s2=iftx(S2); figure(2) imagesc(abs(s)'); axis square;axis xy % % % % p0_2f=exp(j*pi/fc^2/Ka*(FU.*F).^2+j*pi*fdc^2/fc/Ka*F-j*pi/fc/Ka*FU.^2.*F); % % % % S=fty(S); % % % % S=S.*p0_2f; % % %%二次距离压缩 % omga=sqrt(1-lambda*FU1./(2*Vr)); % Hrc=exp(-cj*pi*Xc*c*FU1.^2.*F.^2./(2*Vr^2*fc.^3.*omga.^3)); % Src=ftx(fty(s)); % S=Src.*Hrc; % %%%%三次相位补偿 % PHI=exp(cj*pi*Xc*c*(FU1.^2).*(F.^3)./(2*Vr^2*fc.^4.*(omga.^5))); % S=S.*PHI; % %%%%%距离徙动校正 % EMEND=exp(cj*2*pi*F.*(2*Xc./omga/c)); % S=S.*EMEND; % %%%%%%%%%%%多普勒相位补偿 % COM=exp(cj*2*pi*FU1.*Yc/Vr); % S=S.*COM; S=ftx(s); S2=ftx(s2); S=S.'; S2=S2.'; alpha=3.2;% % dt=1/fs; lambda=c/fc; % df=fs/N; % f=df*(-N/2:N/2-1); f_matrix=repmat(f,Na,1); m=(0:Na-1); m_matrix=repmat(m(:),1,Nr); alpha=alpha/180*pi; Phi_rcmc=exp(-cj*2*pi*dt*tan(alpha)*m_matrix.*f_matrix);%这是什么意思？？ S=S.*Phi_rcmc; S2=S2.*Phi_rcmc; S=S.'; S2=S2.'; s=iftx(S); s2=iftx(S2); figure(3) imagesc(abs(s)'); axis square; axis xy %%%%%%%%%%%%%%方位压缩 S_fut=fty(s); S2_fut=fty(s2); % Ha=exp(cj*pi*FU1.^2/Ka); Uc0=0;%参考目标方位向中心时刻 Rc=Xc/cos(theta);%参考目标中心斜距 Us0=Rc*(cos(theta)*tan(theta+beta/2)-sin(theta));% 目标方位向采样起始时刻 Ue0=Rc*(sin(theta)-cos(theta)*tan(theta-beta/2));%目标方位向采样结束时刻 R0=sqrt(Xc^2+(Yc-U).^2);%雷达和目标之间的瞬时斜距 ta=2*R0/c; sa=exp(-cj*wc*ta).*(U >= (Uc0-Us0) & U <= (Uc0+Ue0)); Nsa=1590; % wina=[zeros((Na-Nsa)/2,1);hanning(Nsa);zeros((Na-Nsa)/2,1)]; wina=hanning(Na); wina=ones(Nr,1)*(wina.'); sa=sa.*wina; Ha=fty(sa); Ha=conj(Ha); S=S_fut.*Ha; s_1=ifty(S); S2=S2_fut.*Ha; s_2=ifty(S2); % save s_1 s_1; % save s_2 s_2; figure(4) imagesc(x,y,abs(s_1)') axis square;axis xy figure(5) imagesc(x,y,abs(s_2)') axis square;axis xy