Detecting and Georegistering Moving Ground Targets in Airborne QuickSAR via Keystoning and Multiple-Phase Center Interferometry

Abstract

Recommended by Frank Ehlers SAR images experience significant range walk and, without some form of motion compensation, can be quite blurred. The MITREdeveloped Keystone formatting simultaneously and automatically compensates for range walk due to the radial velocity component of each moving target, independent of the number of targets or the value of each target's radial velocity with respect to the ground. Target radial motion also causes moving targets in synthetic aperture radar images to appear at locations offset from their true instantaneous locations on the ground. In a multichannel radar, the interferometric phase values associated with all nonmoving points on the ground appear as a continuum of phase differences while the moving targets appear as interferometric phase discontinuities. By multiple threshold comparisons and grouping of pixels within the intensity and the phase images, we show that it is possible to reliably detect and accurately georegister moving targets within short-duration SAR (QuickSAR) images.

The migration compensation methods for DTV based passive radar

“…Methods for range migration compensation include envelope alignment based on envelope correlation proposed by C.C.Chen in 1980s [11], and Keystone transform (KT) in Synthetic Aperture Radar (SAR) proposed by R.P.Perry [12]. KT is used in a wide range of applications [13][14][15] recently. Methods for Doppler migration compensation include Chirp-Fourier transform(CFT) [16,17], fractional Fourier transform (FRFT) and time-frequency method [18], etc.…”