【雷達】模擬合成孔徑雷達(SAR)的點目標仿真
【雷達】模擬合成孔徑雷達(SAR)的點目標仿真
TT_Matlab
博主簡介：擅長智能優(yōu)化算法、神經(jīng)網(wǎng)絡(luò)預測、信號處理、元胞自動機、圖像處理、路徑規(guī)劃、無人機等多種領(lǐng)域的Matlab仿真，完整matlab代碼或者程序定制加qq1575304183。
1 簡介
基于理想情況下聚束式SAR點目標回波信號數(shù)學模型。
2 完整代碼
%%IFFT
in
row
of
matrix
function
s
=
ifty
(
fs
);
s
=
fftshift
(
ifft(fftshift(fs.
’))).’
;
%%FFT
in
column
of
matrix
function
fs
=
ftx
(
s
);
fs
=
fftshift
(
fft(fftshift(s
)));
%%IFFT
in
column
of
matrix
function
s
=
iftx
(
fs
);
s
=
fftshift
(
ifft(fftshift(fs
)));
%%FFT
in
row
of
matrix
function
fs
=
fty
(
s
);
fs
=
fftshift
(
fft(fftshift(s.
’))).’
;
%%================================================================
%%Filename: stripmapSAR.m
%%Help file: stripmapSAR.doc
%%Project: Stripmap SAR Simulation using point targets and Reconstrction
%%================================================================
clear;clc;close all;
%%================================================================
%%Parameter--constant
C=3e8; %propagation speed
%%Parameter--radar characteristics
Fc=1e9; %carrier frequency 1GHz
lambda=C/Fc; %wavelength
%%Parameter--target area
Xmin=0; %target area in azimuth is within[Xmin,Xmax]
Xmax=50;
Yc=10000; %center of imaged area
Y0=500; %target area in range is within[Yc-Y0,Yc+Y0]
%imaged width 2*Y0
%%Parameter--orbital information
V=100; %SAR velosity 100 m/s
H=5000; %height 5000 m
R0=sqrt(Yc^2+H^2);
%%Parameter--antenna
D=4; %antenna length in azimuth direction
Lsar=lambda*R0/D; %SAR integration length
Tsar=Lsar/V; %SAR integration time
%%Parameter--slow-time domain
Ka=-2*V^2/lambda/R0; %doppler frequency modulation rate
Ba=abs(Ka*Tsar); %doppler frequency modulation bandwidth
PRF=Ba; %pulse repitition frequency
PRT=1/PRF; %pulse repitition time
ds=PRT; %sample spacing in slow-time domain
Nslow=ceil((Xmax-Xmin+Lsar)/V/ds); %sample number in slow-time domain
Nslow=2^nextpow2(Nslow); %for fft
sn=linspace((Xmin-Lsar/2)/V,(Xmax+Lsar/2)/V,Nslow);%discrete time array in slow-time domain
PRT=(Xmax-Xmin+Lsar)/V/Nslow; %refresh
PRF=1/PRT;
ds=PRT;
%%Parameter--fast-time domain
Tr=5e-6; %pulse duration 10us
Br=30e6; %chirp frequency modulation bandwidth 30MHz
Kr=Br/Tr; %chirp slope
Fsr=3*Br; %sampling frequency in fast-time domain
dt=1/Fsr; %sample spacing in fast-time domain
Rmin=sqrt((Yc-Y0)^2+H^2);
Rmax=sqrt((Yc+Y0)^2+H^2+(Lsar/2)^2); %SAR姝ｅ鐩爣錛屾墍浠ヤ笌鏈?繙澶勭殑璺濈涓哄悎鎴愬瓟寰勯暱搴︾殑涓?崐
Nfast=ceil(2*(Rmax-Rmin)/C/dt+Tr/dt);%sample number in fast-time domain
Nfast=2^nextpow2(Nfast); %for fft
tm=linspace(2*Rmin/C,2*Rmax/C+Tr,Nfast); %discrete time array in fast-time domain
dt=(2*Rmax/C+Tr-2*Rmin/C)/Nfast; %refresh
Fsr=1/dt;
%%Parameter--resolution
DY=C/2/Br; %range resolution
DX=D/2; %cross-range resolution
%%Parameter--point targets
Ntarget=1; %number of targets
%format [x, y, reflectivity]
Ptarget=[Xmin,Yc,1];
disp(’Parameters:’)
disp(’Sampling Rate in fast-time domain’);disp(Fsr/Br)
disp(’Sampling Number in fast-time domain’);disp(Nfast)
disp(’Sampling Rate in slow-time domain’);disp(PRF/Ba)
disp(’Sampling Number in slow-time domain’);disp(Nslow)
disp(’Range Resolution’);disp(DY)
disp(’Cross-range Resolution’);disp(DX)
disp(’SAR integration length’);disp(Lsar)
disp(’Position of targets’);disp(Ptarget)
%%================================================================
%%Generate the raw signal data
K=Ntarget; %number of targets
N=Nslow; %number of vector in slow-time domain
M=Nfast; %number of vector in fast-time domain
T=Ptarget; %position of targets
Srnm=zeros(N,M);
for k=1:1:K
sigma=T(k,3);
Dslow=sn*V-T(k,1);
R=sqrt(Dslow.^2+T(k,2)^2+H^2);
tau=2*R/C;
Dfast=ones(N,1)*tm-tau’*ones(1,M);
phase=pi*Kr*Dfast.^2-(4*pi/lambda)*(R’*ones(1,M));
Srnm=Srnm+sigma*exp(j*phase).*(0<Dfast&Dfast<Tr).*((abs(Dslow)<Lsar/2)’*ones(1,M));
end
%%================================================================
%%Range compression
tr=tm-2*Rmin/C;
Refr=exp(j*pi*Kr*tr.^2).*(0<tr&tr<Tr);
Sr=ifty(fty(Srnm).*(ones(N,1)*conj(fty(Refr))));
Gr=abs(Sr);
%%Azimuth compression
ta=sn-Xmin/V;
Refa=exp(j*pi*Ka*ta.^2).*(abs(ta)<Tsar/2);
Sa=iftx(ftx(Sr).*(conj(ftx(Refa)).’*ones(1,M)));
Ga=abs(Sa);
%%================================================================
%%graw the intensity image of signal
colormap(gray);
figure(1)
subplot(211);
row=tm*C/2-2008;col=sn*V-26;
imagesc(row,col,255-Gr); %intensity image of Sr
axis([Yc-Y0,Yc+Y0,Xmin-Lsar/2,Xmax+Lsar/2]);
xlabel(’ightarrowitRange in meters’),ylabel(’itAzimuth in metersleftarrow’),
title(’Stripmap SAR after range compression’),
subplot(212);
imagesc(row,col,255-Ga); %intensity image of Sa
axis([Yc-Y0,Yc+Y0,Xmin-Lsar/2,Xmax+Lsar/2]);
xlabel(’ightarrowitRange in meters’),ylabel(’itAzimuth in metersleftarrow’),
title(’Stripmap SAR after range and azimuth compression’),
%%================================================================
%%draw 3D picture
figure(2)
waterfall(real(Srnm((200:205),:)));axis tight
xlabel(’Range’),ylabel(’Azimuth’),
title(’Real part of the raw signal’),
figure(3)
waterfall(Gr((200:205),(600:1000)));axis tight
xlabel(’Range’),ylabel(’Azimuth’),
title(’Stripmap SAR after range compression’),
figure(4)
mesh(Ga((200:300),(750:860)));axis tight
xlabel(’Range’),ylabel(’Azimuth’),
title(’Stripmap SAR after range and azimuth compression’),
%%================================================================
%%draw -3dB contour
figure(5)
a=max(max(Ga));
contour(row,col,Ga,[0.707*a,a],’b’);grid on
axis([9995,10050,-20,20]),
xlabel(’ightarrowitRange in meters’),ylabel(’itAzimuth in metersleftarrow’),
title(’Resolution Demo: -3dB contour’);
%%================================================================
3 仿真結(jié)果
4 參考文獻
[1]呂守業(yè), 龍騰, and 閆肅. "機載聚束式合成孔徑雷達(SAR)點目標的仿真研究." 第十四屆全國遙感技術(shù)學術(shù)交流會 0.
博主簡介：擅長智能優(yōu)化算法、神經(jīng)網(wǎng)絡(luò)預測、信號處理、元胞自動機、圖像處理、路徑規(guī)劃、無人機等多種領(lǐng)域的Matlab仿真，相關(guān)matlab代碼問題可私信交流。
部分理論引用網(wǎng)絡(luò)文獻，若有侵權(quán)聯(lián)系博主刪除。