Interrupted Synthetic Aperture Radar (intSAR)

New and developmental multi-function radar employ active antenna arrays to fulfill multiple radar modes with a single aperture. This is particularly attractive for unmanned aerial vehicles, where form factor and size are highly constrained. For example, the Multi-Platform Radar Technology Insertion Program intended for the RQ04B Global Hawk is in tended to gather Synthetic Aperture Radar (SAR) and Ground Moving Target Indication data simultaneously. A SAR system can be made compatible with other interleaved modes if the effects of the interruptions in SAR data gathering necessary to accommodate these other modes can be ameliorated. SSCI and our subcontractor GOLETA Engineering propose to characterize and quantify how these interruptions affect SAR image quality and utility, and to develop gap-filling algorithms that accurately recover the missing phase-history data, thus providing formed SAR imagery containing minimal artifacts. BENEFIT: One of the critical radar functions is the collection of radar data to form good quality, high-resolution SAR imagery. The severe timeline demands imposed by the multi-mode functions of modern airborne radars utilizing active array antennas may result in interrupted SAR data collections -- and thus the SAR images may be corrupted. Characterizing the effects of interruptions on SAR image quality using phase-history data having data-gaps is essential to understanding the quality and the utility of the imagery in SAR imaging modes from simple visual exploitation of the imagery by image analysts to the more advanced image exploitation modes such as interferometric imaging and coherent change detection. The benefits of this"interrupted SAR"research program are the development of new SAR signal processing and image formation algorithms that accurately recover image quality, permitting interleaving of other modes during SAR data collection in order to enhance the pilot"s situational awareness.