SYNTHETIC APERTURE RADAR (SAR) ENHANCING TECHNIQUES

SAR is a critical technology for obtaining military and economic intelligence, terrain height and cover information, and a variety of other data. Because of its long coherent integration times and wide bandwidth, SAR is extremely vulnerable to RF interference, intentional noise jamming and coherent repeater jamming. The proposed research will identify the sources of interference that affect SARs operating in different frequency bands, quantify the effects of this interference on the SAR image and develop (to a first level) concepts that can negate the intereference. The techniques for rejecting the interference include space-time adaptive processing, adaptive time gating and frequency domain nulling, coherent signal subtraction and monopulse processing/cell censoring. Also investigated will be interpolation techniques to restore the portions of the signal lost due to the gating and filtering of the interference.A matrix will be generated that summarizes the impact of each interference source on the SAR's performance, the interference rejection required, the ability of the jammer negation techniques to achieve these requistite levels and the cost of incorporating each negation concept. This matrix will help to identify the most critical threats and the optimal rejection techniques for a Phase II development and demonstration program.