Two-stage estimation of spacecraft position and velocity via single station antenna tracking data

In this study, a two-stage approach for estimation of spacecraft´s position and velocity by single station antenna tracking data is proposed. In the first stage, direct nonlinear antenna measurements are transformed to linear x-y-z coordinate measurements of spacecraft´s position, and statistical characteristics of orbit determination errors are analyzed. Variances of orbit parameters´ errors are chosen as the accuracy criteria. In the second stage, the outputs of the first stage are improved by the designed EKF for estimation of the spacecraft´s position and velocity on indirect linear x-y-z measurements. Two recursive EKF algorithms are examined: the first designed filter estimates the position and velocity of the spacecraft on direct nonlinear range-azimuth-elevation measurements; the second one carries out the estimation on indirect linear x-y-z position measurements. The examined filters are compared through geostationary satellite orbital motion simulations, and the recommendations on their application for various spacecraft missions are given.