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
res_r=2;										%?required?range?resolution
k_a=1.2;										%?azimuth?factor
k_r=1.2;										%?range?factor

Ra=4000.;									%?radar?working?distance
va=70.;?										%?radar/platform?forward?velocity
Tp=1.e-6;?									%?transmitted?pulse?width??????
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（NaNr）;?
for?i=1:Na			
	for?k=

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件??????57440??2007-06-23?15:44??sar_echo.m

-----------?---------??----------?-----??----

????????????????57440????????????????????1