nene.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] = nene(z,rho,theta)
% function NENE.M
% Nearest neighbor approximation algorithm
% [s,V] =  nene(z,rho,theta)
% z = M by N matrix with samples in frequency domain 
% rho, theta = radius and angles ofdata points
% interpolated matrix
% V = vector that includes [X0 dkx dky fl]

close all
% Variables bursts
 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);

% Points of Interpolation
 x = linspace(min(rhov), max(rhov)*cos(ac/2),pul_burst);
 y = min(rhov)*tan(ac/2)*linspace(-1,1,bursts);
 [fxi,fyi] = meshgrid(x,y);
 fxd = rho.*cos(theta);
 fyd = rho.*sin(theta);
 dkx = fxi(1,2) - fxi(1,1);
 dky = fyi(2,1) - fyi(1,1);
 X0 = pi/(rhov(2) - rhov(1));

% Interpolation
 flops(0)
 s = zeros(size(z));
 for a = 1:bursts,
    for b = 1:pul_burst,
       rr = sqrt(fxi(a,b)^2 + fyi(a,b)^2);
       tt = atan2(fyi(a,b),fxi(a,b));
       n = 1 + fix((rr - min(rhov))/drho);
       c = rr - (min(rhov) + drho*(n-1));
       t2 = (theta(:,n+1) - theta(:,n))*c/drho + theta(:,n);
       if a==128
         tt=tt-0.001;
       end
       k = min(find(tt<t2)) - 1;
       vx = [fxd(k,n) fxd(k+1,n) fxd(k+1,n+1) fxd(k,n+1)];
       vy = [fyd(k,n) fyd(k+1,n) fyd(k+1,n+1) fyd(k,n+1)];
       d = sqrt((fxi(a,b)-vx).^2)+sqrt((fyi(a,b)-vy).^2);
       kk=[k n;k+1 n;k+1 n+1;k n+1];
       [c1,c2] = min(d);
       k1 = kk(c2,1); k2 = kk(c2,2);
       s(a,b) = z(k1,k2);
 end; end
 fl = flops;
 V = [X0 dkx dky fl];