A Novel Method for Radar Initial Orbit Determination from Angular Track and Doppler Shift Measurements

The overpopulation of resident space objects requires an efficient space objects cataloguing capability. This paper describes a novel radar Initial Orbit Determination (IOD) algorithm when only angular track and Doppler shift measurements are available. First, a track compression is performed to derive the time derivative of the angular pair. An optical admissible region is computed, considering semi-major axis, range and eccentricity constraints. For bistatic radars, this region is converted to the bistatic plane. An admissible line is identified from the intersection of the admissible region with the measured range rate (derived from the Doppler shift) and then sampled, providing orbital state candidates. One of them enters a batch filter as first guess, from which the IOD result is returned. The algorithm is validated using both numerical simulations and real data. The algorithm is applicable to any survey radar and offers greater reliability and ease of operational than existing methods.