Detecting Moving Targets
in Clutter in Airborne SAR via Keystoning and Multiple Phase Center Interferometry
April 2006
D. M. Zasada, The MITRE Corporation
P. K. Sanyal, The MITRE Corporation
R. P. Perry, The MITRE Corporation
ABSTRACT
Without motion compensation, Synthetic Aperture Radar (SAR) images
of the ground are generally blurred. In 1997, MITRE reported the development
technique called the Keystone Process for removing the range migration
caused by the radial velocity component of each pixel's movement
within the scene, whether moving or stationary with respect to the ground.
When applied to multiple phase center phased array radar data, this
first pass process allows for automated detection of moving targets
via phase thresholding. Once detected in phase space, the moving targets
can be individually and automatically focused using the procedures previously
reported. Automated positioning of the detected target within the formed
image is then accomplished (georegistration)
We can easily detect and accurately georegister bright (large radar
cross-sections) moving targets using a phase threshold technique reported
herein. However, we have found that, for smaller targets, the phase
differences between the cells containing the moving target can be greatly
distorted by the presence of strong ground clutter. Only after the ground
clutter is cancelled will the phase difference be sufficiently dominated
by the target response to allow accurate geo-positioning. Herein we
describe one technique whereby the clutter may be cancelled by using
multiple phase centers.
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