US 7,532,150 B1
Restoration of signal to noise and spatial aperture in squint angles range migration algorithm for SAR
Theagenis J. Abatzoglou, Huntington Beach, Calif. (US); and Leo H. Hui, Alhambra, Calif. (US)
Assigned to Raytheon Company, Waltham, Mass. (US)
Filed on Mar. 20, 2008, as Appl. No. 12/77,669.
Int. Cl. G01S 13/90 (2006.01)
U.S. Cl. 342—25F  [342/25 A; 342/25 R] 16 Claims
OG exemplary drawing
 
1. A radar for generating a search mode synthetic aperture image of a patch having a principal scatterer from periodic pulse returns reflected from said patch and said principal scatterer, said radar having a motion, said radar having an antenna illuminating boundaries of said patch from R0 slant range to R1 slant range and from an azimuth angle θ0 to an azimuth angle θ1, said radar comprising:
an analog to digital converter for converting said pulse returns into a plurality of digital samples;
a computer for:
motion compensating said digital samples with respect to said motion to obtain a motion compensated digital array;
converting said motion compensated digital array to a frequency array in a frequency domain Kx, Ky using a transform, said frequency domain having coordinates having a Kx axis and a Ky axis, said frequency array having a rectangular aperture, said rectangular aperture extending ΔKx along said Kx axis, said rectangular aperture extending ΔKy along said Ky axis;
computing available samples from said frequency array in said frequency domain using a Range Migration Algorithm including a Stolt interpolation;
identifying usable samples from said available samples using one or more criteria;
removing said usable samples from said available samples to obtain incomplete samples;
extracting features related to said patch having a principal scatterer from said usable samples;
using said features to extrapolate extrapolated samples from said usable samples;
combining said extrapolated samples said usable samples and said incomplete samples for computing said search mode synthetic aperture image of said patch and said principal scatterer.