Revolutionary AUTOFOCUS for High-Resolution Coherent Radar Imaging Systems

Period of Performance: 01/14/2003 - 07/14/2003


Phase 1 SBIR

Recipient Firm

Vexcel Corp.
1690 38th Street
Boulder, CO 80301
Principal Investigator


Vexcel Corporation proposes the implementation of a recently invented AUTOFOCUS technique as a revolutionary new way to correct defocus and remove blurring from coherent two-dimensional (2D) radar imagery and as an enabling technology for emerging coherent three-dimensional (3D) imaging systems. High-resolution 2D coherent radar imaging is a critical component in existing ballistic and theater missile defense systems and provides data for advanced detection, tracking, and discrimination processing. Unavoidable aperture synthesis errors (e.g. inaccuracies in target location estimates, ionospheric propagation dynamics, etc.) lead to phase errors that cause defocusing in radar imagery. As these effects change during the aperture time, they cause a fully-coupled 2D phase error that cannot be corrected using conventional algorithms. Potential operation in a nuclear environment holds the possibility of very significant exaggeration of these types of effects. A recent Vexcel study to extend the established Phase Gradient Autofocus algorithm to 2D revealed theoretic limitations and lead to the discovery/invention of the proposed autofocus technique. Preliminary results show this technique to be a much more robust method for removing severe fully-coupled 2D errors from data, vastly improving image quality in many cases where the 2D PGA technique showed practically no improvement. Vexcel expects to realize commercial benefits directly and indirectly from this effort. This technique is new and, as yet, not fully validated. A Phase I & II effort will help verify and valid performance and determine operational characteristics. The indirect commercial benefits lie in the fact that Vexcel is one of the largest sellers of commercial satellite ground station hardware and SAR processing software in the world. During the development of such advanced processing systems new algorithms, methods, and techniques are always realized. As these capabilities become available, they are often incorporated into existing SAR processing products as improvements, forming a better, more capable product and increasing it?s marketability. As many of our SAR processing software packages generate value-added data products from coherent data, we expect that the experience gained from the implementation and study of 2D and 3D phase correction, where coherence is so critical, will provide benefits not yet foreseen to be incorporated and used in our commercial products.