On-board orbit and clock determination based on cross-link observables: Ranging and Time Transfer Provision System

Recent ESA research activities, within the GNSS Evolution Programme (GNSS EP) and within the General Study Programme (GSP), have investigated ground-to-space and space-to-space long-range cross-links techniques for accurate ranging and time-transfer [1] enabling, amongst a wide range of improvements, to place an accurate and significantly autonomous orbit and time determination function on-board a GNSS satellite. This investigation is now extended to other type of orbits namely MEO (different from GNSS), GEO, HEO or even LEO, and required adaptations are studied in the frame of RTPS (Ranging and Time-transfer Provision System) project. In this paper the main characteristics of the on-board OD&TS based on satellite-to-station cross links are described and the time performances of coupled and uncoupled OD&TS processing schemes are compared.