SBIR-STTR Award

A target angle estimation technique making effective use of the spatial degrees of freedom of an adaptive array radar system has been developed by ASI and demonstrated to yield unbiased and efficient angle estimates in near-main beam jammer environments. The program objective of progressing towards a feasibility demonstration includes optimizing system designs including the detection and post-detection angle estimation functions for specific long wavelength low observable adaptive array airborne and ground-based radar systems. For the airborne (STAP) radars, the designs will include effective cancellation of both direct side lobe and near-main lobe jamming and the terrain scatter jamming, ground clutter. The simulation models developed in the Phase I program will be designed for use during the Phase II program with field-acquired, multiple-channel data as inputs. For low target elevation angles, adaptive array radar angle estimation techniques specifically designed to mitigate the target multipath degradation effects - and based on two ASI proprietary approaches - will be further developed and evaluated. Candidate DoD radar test beds for use during a Phase II program have been identified and provide the basis for a detailed Phase II plan to be developed.

Space-Time Adaptive Processing (STAP), using multiple beam and/or aperture arrays, makes possible the rejection of mainbeam and sidelobe jamming, and greatly improves the performance of AI radars in ground clutter. When the antenna ports are used adaptively to suppress interference, monopulse beam-splitting techniques using sum and difference apertures produce significant bias errors and prevent accurate angle measurements. Fortunately, unbiased angle estimates can be obtained using the same processing hardware and software required for STAP. This is being demonstrated with the PC-based Matlab simulation program developed in SBIR I. While this Adaptive Maximum Likelihood Estimate (AMLE) algorithm is believed to be the best and simplest to use with STAP, more programming and testing is needed to bring it into operational use in a timely manner. The amount of calibration data required must be determined. This SBIR II will support further development and testing of this and other angle estimation algorithms using the ASI program with the TI radome simulation code and with field data acquired on the TI range using the ATCK GP3 system. The TI range and GP3 system will be used for demonstrations in near-real time on antennas with and without radomes.