Preliminary Orbit Estimation for Turksat 5B via Extended and Unscented Kalman Filtering

Turksat 5B is a Turkish geostationary communications satellite operated by Turksat A.Ş which was launched on 19 December 2021 for commercial purposes. To determine its orbit, that is, its state vector in space, range, azimuth, and elevation angles are utilized in conjunction with Extended and Unscented Kalman filter (EKF and UKF) algorithms. Following the estimation results from these filters, their performance is compared in terms of both accuracy and computational burden. In this endeavor, several simulations are performed in which it is assumed that a single-station antenna exists in Istanbul at 41.10° latitude and 29.02° longitude. This single-station antenna provides range and angle measurements, which are then indirectly used in the filtering algorithm. Utilizing these measurements indirectly implies that they undergo pre-processing to obtain the satellite’s position vector in the Earth Centered Inertial (ECI) frame. This pre-processing simplifies the EKF observation matrix and enhances the initial filter convergence.