CHAMP orbit determination with GPS phase-connected precise point positioning

A completely geometric approach for precise orbit determination (POD) of low earth orbiters (LEOs) is presented, which does not rely on dynamic models, but only data from a GPS receiver onboard a LEO and the International GPS Service (IGS) GPS orbit and clock products. Initial processing of CHAMP receiver data indicated measurement anomalies requiring additional pre-processing. The exising of outliers becomes a significant concern in the processing, given that this results in significant gaps in datasets. Intermediate processing results indicate that orbit comparison precision approaching 30 em r.m.s. in each position component is attainable. However, these results are severely impacted by the near ubiquitous data gaps in the preprocessed measurements. However, initial analysis of recent data indicates quality datasets capable of providing near-decimetre-level precision.