threest.m

进行ISAR运动补偿的程序 kylsdone 方法来消除越距离单元走动,注释完整

function [s,V] = threest(z,rho,theta)
% function THREEST.M
% Interpolation Method using three steps
% Usage: [s,V]  threest(z,rho,theta)
% Where: z = M by N matrix with samples in frequency domain
% rho, theta  radius and angles of data points
% s = interpolated matrix
% V = vector that includes [X0 dkx dky fl]
% Example using cubic spline interpolation frinction

close all

% Variables
 bursts = size(z,1);
 pul_burst = size(z,2);
 rho = rho.*(4*pi/3e8);   %% frequency matrix in rad/mt
 rhov = rho(1,:);
 drho = rhov(2) - rhov(1);
 ac = theta(bursts,1) - theta(1,pul_burst);
 
% Interpolation, First step (radial)
 flops(0);
 s = zeros(size(z));
 t = linspace(theta(1,pul_burst), theta(bursts,1), bursts);
 t1 = meshgrid(t, 1:pul_burst)';
 fxd = rho.*cos(theta); fxi = zeros(size(fxd));
 fyd = rho.*sin(theta); fyi = fxi;
 for a = 1:pul_burst,
    for b = 1:bursts,
       ind = find(t1(b,a)==theta(:,a));
       if isempty(ind), % interpolate
          ind = max(find(t1(b,a)>theta(:,a)));
          th0 = theta(ind,a);
          th1 = theta(ind+1,a);
          gg = (pi + th0 - th1)/2;
          bb = (pi + th0 + th1 - 2*t1(b,a))/2;
          rr = rho(b,a)*sin(gg)/sin(bb);
          fxi(b,a) = rr*cos(t1(b,a));
          fyi(b,a) = rr*sin(t1(b,a));
          d1 = ((fxd(ind,a) - fxd(ind+1,a))^2 + (fyd(ind,a) - fyd(ind+1,a))^2)^.5;
          d2 = ((fxd(ind,a) - fxi(b,a))^2 + (fyd(ind,a) - fyi(b,a))^2)^.5;
          s(b,a) = (z(ind+1,a) - z(ind,a))*d2/d1 + z(ind,a);
       else % don't interpolate
          fxi(b,a) = fxd(ind,a); fyi(b,a) = fyd(ind,a);
          s(b,a) = z(ind,a);
 end; end; end
 flo = flops;
 
  % Interpolation, Second step (x)
  z=s;
  rho = (fxi.^2 + fyi.^2).^.5; 
  theta = atan2(fyi,fxi);
  rho = rho./(4*pi/3e8);
  [s,V]=normal_l(z,rho,theta); %Modifly this line according to desired function
  %[s,V]=normal_c(z,rho,theta);
  %[s,V]=sinky(z,rho,theta);
  V(4)=V(4) + flo;