Orbit determination via UD-filters

The application of UD Filter (UDF) and UD-Filter-RTS Smoother (UDRS) to estimate the orbital states of a search and rescue satellite aided tracking (SARSAT) satellite is considered. Inertial co-ordinates´ six states (IC6) for the filter and Altman´s Unified State Model´s (USM)-seven states (U7) for the time propagation are used. The angles and range data simulated for groundbased tracking site are considered as observables. The UD algorithms performed with acceptable accuracy in satellite position estimation.