Synthetic Aperture Radar (SAR) Aided Navigation

ABSTRACT: The objective of this effort is to develop an algorithmic framework for joint utilization of GPS/INS/SAR in order to simultaneously improve the localization accuracy and integrity of an airborne sensor system's navigation system. The primary challenges from a SAR-processing perspective are a) the estimation of position and velocity states directly from SAR phase history data and b) the development of a realistic model to calculate uncertainty estimates associated with the SAR-based (position, velocity)-state estimates for use in an integrated navigation system. From a more traditional navigation viewpoint, a significant challenge arises in the incorporation of the noisy SAR-based (position, velocity) estimates -- which are inherently associated with the approximate phase center of the SAR antenna -- within an overall navigation system. This effort will focus on developing real-time implementations of the algorithms proved successful in the prior Phase I effort (the autofocus- and feature-based motion estimation algorithms, as well as the generic navigation filter). The efficiency and efficacy of these algorithms will be demonstrated through real-time data collections measured on an Air Force platform. Although the demonstration will be application-specific, our approach is general enough to apply to several different types of (airborne and ground-moving) ISR platforms. BENEFIT: The primary benefit of successful completion of this effort is a revolutionary new capability for improving overall geolocation accuracy and integrity for platforms with radar assets. This capability has numerous commercial applications in various business sectors such as defense, mapping, and transit.