clc
clear
close all距离向参数
R_eta_c = 20e3;             % 景中心斜距
Tr = 25e-6;                 % 发射脉冲时宽
Kr = 0.25e12;               % 距离向调频率
Fr = 7.5e6;                 % 距离向采样率
Nrg = 256;                  % 距离线采样点数
Bw = abs(Kr*Tr);            % 距离信号带宽方位向参数
Delta_f_dop = 80;           % 多普勒带宽
Fa = 104;                   % 方位向采样率
Naz = 256;                  % 距离线数；
theta_sq_c = [0,22.8];      % 波束斜视角
eta_c = [0,-51.7];          % 波束中心偏移时间
f_eta_c = [0,2055];         % 多普勒中心频率
Vr = 150;                   % 等效速度其他参数
c = 3e8;
f0 = 5.3e9;
lambda = c/f0;
R0 = R_eta_c*cosd(theta_sq_c(2));   % 最短斜距
La = 0.886*(2*Vr*cosd(theta_sq_c(2)))/Delta_f_dop;  % 真实孔径
theta_bw = 0.886*lambda/La;         % 方位向波束宽度
Trr = Nrg/Fr;                       % 发射脉冲时宽
Taa = Naz/Fa;                       % 目标照射时间
Ka = 2*Vr^2*cosd(theta_sq_c(2))^2/lambda/R0;              % 方位向调频率
d_t_tau = 1/Fr;                     % 距离采样时间间隔
d_t_eta = 1/Fa;                     % 方位采样时间间隔
d_f_tau = Fa/Nrg;                   % 距离采样频率间隔
d_f_eta = Fa/Naz;                   % 方位采样频率间隔变量设置
tau = (-Trr/2:d_t_tau:Trr/2-d_t_tau)+2*R_eta_c/c;     % 距离时间变量
eta = (-Taa/2:d_t_eta:Taa/2-d_t_eta)+eta_c(2);        % 方位时间变量坐标设置
[tauX,etaY] = meshgrid(tau,eta);        % 二维网格坐标  信号设置
% R_eta = R0+Vr^2*etaY.^2/2/R0;           % 瞬时斜距
R_eta = sqrt(R0^2 + Vr^2*etaY.^2);
A0 = 1;                                 % 后向散射系数幅度
wr = (abs(tauX-2*R_eta/c) <= Tr/2);     % 距离向包络
wa = sinc(0.886*atan(Vr*(etaY-eta_c(2))/R0)/theta_bw).^2;   % 方位包络
srt = A0*wr.*wa.*exp(-1j*4*pi*f0*R_eta/c)....*exp(+1j*pi*Kr*(tauX-2*R_eta/c).^2);                                                           
srt_z = A0*wr.*wa.*exp(-1j*4*pi*f0*R_eta/c)...              .*exp(+1j*pi*Kr*(tauX-2*R_eta/c).^2);% 正扫频
srt_f = A0*wr.*wa.*exp(-1j*4*pi*f0*R_eta/c)... .*exp(-1j*pi*Kr*(tauX-2*R_eta/c).^2);% 负扫频
% srt = A0*wr.*wa.*exp(-1j*4*pi*R0/lambda)...
%                .*exp(-1j*pi*Ka*etaY.^2)...
%                .*exp(1j*pi*Kr*(tauX-2*R_eta/c).^2);
% srt_z = A0*wr.*wa.*exp(-1j*4*pi*R0/lambda)...
%                .*exp(-1j*pi*Ka*etaY.^2)...
%                .*exp(1j*pi*Kr*(tauX-2*R_eta/c).^2); % 正扫频
% srt_f = A0*wr.*wa.*exp(-1j*4*pi*R0/lambda)...
%                .*exp(-1j*pi*Ka*etaY.^2)... 
%                .*exp(-1j*pi*Kr*(tauX-2*R_eta/c).^2); % 负扫频绘图
figure
imagesc(abs(srt_z))
colorbar
figure
imagesc(angle(srt_z))
figure
imagesc(angle(srt_f))