mlbf.pro

在雷达成像中所用到的多普勒质心估计

parameters
common para


in_echo=dcomplexarr(range_samples)
test_data=dcomplexarr(azimuth_samples,range_samples)
band_look=B*2./3.;;*0.85
band_cut=ceil((fs-band_look)/(fs/range_samples))/2
look1=dcomplexarr(azimuth_samples,range_samples/2-band_cut)
look2=dcomplexarr(azimuth_samples,range_samples/2-band_cut)
look11=dcomplexarr(azimuth_samples,range_samples/2-band_cut)
look22=dcomplexarr(azimuth_samples,range_samples/2-band_cut)

tao=-T_tao/2.+findgen(range_samples/2-band_cut)*T_tao/(range_samples/2-band_cut)
aver_center=0.
range_filter=dcomplexarr(range_samples)
range_f=-fs/2.+findgen(range_samples)*fs/range_samples
range_filter=exp(dcomplex(0,-range_f^2*!pi/k))
start_echo=0LL
openr,1,rawdata_filename
point_lun,1,start_echo*range_samples*8LL
for ia =0LL,azimuth_samples-1LL  do begin
   readu,1,in_echo
   test_data[ia,*]=shift(fft(in_echo,-1),-range_samples/2)*range_filter

endfor

;;look1[*,0:azimuth_samples/2-1]=test_data[*,0:azimuth_samples/2-1]
for ir=0,range_samples/2-band_cut-1LL do begin
   look11[*,range_samples/2-band_cut-1-ir]=test_data[*,ir+band_cut];;/abs(test_data[*,ir+band_cut])
   look22[*,ir]=test_data[*,range_samples/2+ir-1];;/abs(test_data[*,range_samples/2+ir-1])

endfor
close,1

for ia=0,azimuth_samples-1LL do begin
   look1[ia,*]=fft(look11[ia,*],1);;*exp(dcomplex(0,-band_look/4.*tao))
   look2[ia,*]=fft(look22[ia,*],1);;*exp(dcomplex(0,band_look/4.*tao))

endfor

;for ia=azimuth_samples/2-500,azimuth_samples/2+499LL do begin
;   look1[ia,*]=shift(fft(fft(look1[ia,*],1)*exp(dcomplex(0,-band_look/4.*tao)),-1),-(range_samples/2-band_cut)/2)
;   look2[ia,*]=shift(fft(fft(look2[ia,*],1)*exp(dcomplex(0,band_look/4.*tao)),-1),-(range_samples/2-band_cut)/2)
;
;endfor

;for ia=0,azimuth_samples-1LL do begin
;   look1[ia,*]=fft(look1[ia,*],1)*exp(dcomplex(0,-B/4.*tao))
;   look2[ia,*]=fft(look2[ia,*],1)*exp(dcomplex(0,B/4.*tao))
;
;endfor


mlbf=look1*conj(look2)

for ir=0,range_samples/2-band_cut-1LL do begin
   mlbf[*,ir]=shift(fft(mlbf[*,ir],-1),-azimuth_samples/2)
   aver_center=aver_center+where(abs(mlbf[*,ir]) EQ max(abs(mlbf[*,ir])))
endfor

aver_center=aver_center/(range_samples/2-band_cut)

f_beat=PRF/azimuth_samples*(aver_center-azimuth_samples/2)

doppler_ambiguity=-f_beat*(c/lamd)/(band_look/2.)

stop

end