Coordinate Registration (CR) of OTHR targets requires accurate real-time ionospheric modeling coupled with HF propagation calculations to convert radar-detected target delays and beam steers to geographical positions. Our team has developed a comprehensive ionospheric data assimilation capability called GPSII. Within proposed effort GPSII will be matured for OTHR CR. Of particular value are recently introduced GPSII capabilities to assimilate Known Reference Points (KRPs) and Unknown Reference Points (URPs). The latter refers to the process of joint estimation of ionospheric state and targetsÂ’ geo-positions. In Phase I we will advance the URP approach to CR. The workflow for supplying data for robust GPSII-CR operation will be established. The driving data will include backscatter ionograms, vertical ionograms, air and marine traffic reports (to be used as KRPs in GPSII), ionospheric Doppler. New GEOINT tools for ray-tracing-driven CR will be demonstrated. The improved propagation model is expected to enhance target detection when our SIFTER radar signal processing method is employed. This method interprets OTHR signal in terms of distribution of scatterers in ground coordinates. Multiple-mode returns produced by a target are effectively collapsed into an enhanced peak on the scattering surface. Investigation of SIFTER method with GPSII ionosphere will lead to Phase II.
