SBAS with ground based atomic reference station

Abstract

To provide the proper positioning signal, global navigation satellite systems (GNSSs), need very accurate satellite on-board time references. For GPS, GLONAS and GALILEO, such time references are spaceborn atomic clocks. The augmentation/positioning system QZSS (Quasi-Zenith Satellite System) would need the same kind of accuracy. However, due to the high QZSS satellite visibility, a completely new kind of time reference method, where no on-board atomic references are needed, could be adopted. If an opportune ground location is chosen, QZSS satellites are fully visible for the whole orbital period. Therefore, a main time reference (atomic clock), located on the ground, could be kept synchronized to a inexpensive and compact time reference (VCXO) on board each QZSS satellite. In the following article, a new practical implementation of such a remote synchronization method is proposed and some of its problematic are discussed.