【雷达图像】SAR合成孔径雷达成像及处理matlab源码

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一、简介

二、源代码

clear all;
%======================================================================
%%% (I) parameters' definition
%======================================================================
c=3e+8;										% speed of light
pi=3.1415926;	 					   	% pi
j00=sqrt(-1);							   % square root of -1
 
res_a=2;										% required azimuth resolution
k_r=1.2;										% range factor
 
Ra=4000.;									% radar working distance
va=70.; 										% radar/platform forward velocity
fc=3.e+9;	 						   	% carrier frequency 
FsFactor = 1.0;
theta=90*pi/180;						   % squint angle   
 
%======================================================================
 
lamda=c/fc;									% wavelength
Br=k_r*c/2./res_r;					   % required transmitted bandwidth
Fs=Br*FsFactor;						   % A/D sampling rate
bin_r=c/2./Fs;							   % range bin
Kr=Br/Tp;					  		      % range chirp rate	  
 
La=Ra*k_a*lamda/2/res_a;            % required synthetic aperture length
Ta=La/va;									% required synthetic aperture time
fdc=2*va*cos(theta)/lamda;          % doppler centriod
fdr=-2*(va*sin(theta)).^2/lamda/Ra;	% doppler rate
Bd=abs(fdr)*Ta;						   % doppler bandwidth
prf=round(Bd*2);						   % PRF	
 
%======================================================================
%%%(II) echo return modelling (point target)
%======================================================================
 
na=fix(Ta*prf/2);							% azimuth sampling number
ta=-na:na;											
ta=ta/prf;								   % slow time along azimuth
xa=va*ta-Ra*cos(theta);				   % azimuth location along flight track
Na=2*fix(na);
 
%x0=[  0  0  0  0  0 ];             % define multi points if you want
%R0=[-20 -10 0 10 20 ];             % x0: azimuth location (positive towards forward velocity)
                                    % R0: slant range location (positive towards far range)
 
x0=[ 0 0 ];  R0=[ 0 10 ];                % only one point
Npt_num = length(x0);
 
ra=zeros(Npt_num, length(xa));      % calculate every point target's slant range history
for i=1:Npt_num                                    
	ra(i,:)=sqrt((Ra*sin(theta)+R0(i)).^2+(xa+x0(i)).^2);		 
end   
 
rmax=max(max(ra));						% max. slant range
rmin=min(min(ra));						% min. slant range
rmc=fix((rmax-rmin)/bin_r);			% range migration,	number
 
rg=0*ra;                            % initialize 
rg=fix((ra-rmin)/bin_r+1);				% range gate index caused by range migration
rgmax=max(max(rg));
rgmin=min(min(rg));
 
nr=round(Tp*Fs);							% samples of a pluse
tr=1:fix(nr)+1;									
tr=tr/Fs-Tp/2;								% fast time within a pluse duration
Nr=nr+rgmax;
 
%======================================================================
%%%(II) echo return modelling (point target)
%======================================================================
 
sig=zeros(Na,Nr); 
for i=1:Na			
	for k=1:Npt_num
  		sig(i,rg(k,i):rg(k,i)+nr)=sig(i,rg(k,i):rg(k,i)+nr)+exp(-j00*4*pi/lamda*ra(k,i))*exp(-j00*pi*Kr*(tr).^2);
   end  
end
%%%  parameters' definition
c=3e+8;										% speed of light
pi=3.1415926; 
j=sqrt(-1);	
 
Tp=1.e-6; 								% transmitted pulse width      
fc=1.e+9;	 						   	% carrier frequency 
Br=50.e+6;              % transmitted bandwidth
Fs=200.e+6;             % A/D sample rate
kr=Br/Tp;               % range chirp rate
 
Nr=Tp*Fs;
Ni=1:Nr;
tr=(Ni-Nr/2)*Tp/Nr;
 
%===============================
%Chirp pulse echo from point A
%===============================
 
sig_point0 = exp(j*pi*kr*(tr).^2);
 
%===============================
%Chirp pulse echo from point B
%===============================
 
dr=3;  dr_t=2*dr/c;  dN=dr_t*Fs;
sig_point1 = exp(j*pi*kr*(tr-dr_t).^2);
 
sig_0 = zeros(1, 3*Nr); sig_1 = sig_0; sum_sig = sig_0;
 
sig_0(Nr+1:2*Nr)=sig_point0;
sig_1(Nr+dN+1:2*Nr+dN)=sig_point1;
 
%===============================
% Summary echo signal of A and B
%===============================
 
sum_sig = sig_0 + sig_1;
 
figure;
subplot(4,1,1); plot(real(sig_0));
subplot(4,1,2); plot(real(sig_1));
subplot(4,1,3); plot(real(sum_sig));

三、运行结果

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