Detecting Moving Targets in SAR Via Keystoning and Phase Interferometry

We require continuous and unambiguous radar tracking of surface moving targets for several minutes to target and engage moving targets. Conventional radar surface moving target trackers typically drop or confuse tracks after only a short time. If we can couple state of the art motion-compensated Synthetic Aperture Radar (SAR) techniques with advanced Surface Moving Target Information (SMTI) techniques, we may be far better able to automatically and continuously track individual targets through zero radial velocity in difficult environments. Without motion compensation, moving targets within SAR images are generally blurred and difficult to detect . MITRE has developed a technique called the Keystone Formatting for motion compensation of targets, the advantage of which is that it can compensate for several targets moving at different velocities simultaneously. Along with acceleration correction, this produces sharp images. Complimentary to the Keystone’d Range-Doppler-Intensity image, one can form a phaseinterferometry image. In the phase image, where all points on the non-moving surface nominally appear as a continuum of phase differences while the moving targets appear as discontinuities. By judicious comparison of both the intensity image and the phase image, it is possible to detect and locate moving targets in the SAR.