PRECISE RELATIVE NAVIGATION FOR HIGHLY VARIABLE BASELINES USING CARRIER-BASED DIFFERENTIAL GPS

This paper addresses the problem of determining the baseline of formation flying satellites using carrier-based differential GPS. Specifically, a dynamic-filtering scheme relying on an Extended Kalman Filter is proposed to determine the baseline with high accuracy in space applications characterized by a high variability of the intersatellite distance. These applications cover a broad range of space missions, from in-orbit servicing to Earth remote sensing. In the paper, a filtering scheme is proposed constituting a unique environment in which either single or dual frequency double-differenced pseudorange and carrier-phase measurements can be filtered out to determine in real time the relative position. Filter performance with single and dual frequency GPS receivers is numerically analysed considering orbital scenarios relevant to the considered applications. Results demonstrate filter robustness and capability of providing real-time baseline determination at the sub-centimetre level.