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This dissertation presents a novel satellite timekeeping system which does not require on-board atomic clocks as used by existing navigation satellite systems such as GPS, GLONASS or the planned GALILEO system. This concept is differentiated by the employment of a synchronization framework combined with lightweight steerable on-board clocks which act as transponders re-broadcasting the precise time remotely provided by the time synchronization network located on the ground. This allows the system to operate optimally when satellites are in direct contact with the ground station, making it suitable for a system like the Japanese Quasi-Zenith Satellite System, QZSS. Low satellite mass and low satellite manufacturing and launch cost are significant advantages of this novel system. Two possible implementations of the time synchronization network for QZSS are presented. Additionally, the problem of satellite communication interruption is analyzed and a solution is presented. Finally a positioning and timing quality analysis, aimed to provide understanding of the actual timing quality requirements for QZSS, is presented.

A positioning performance analysis of the RESSOX synchronization network for the Japanese Quasi-Zenith Satellite System, QZSS, is presented. A hardware-in-the-loop experiment setup has been developed to study concrete effects on positioning when a real space-born OCXO is employed in the atomic clock-less RESSOX architecture. This study focuses on a positioning performance analysis of QZSS used in conjunction with GPS. Particular focus is given to the effects of faulty synchronization on positioning, specifically when, because of unavoidable communication interruptions, the QZSS satellite clock has to function without remote control. Results show that the recently proposed RESSOX phase error compensation method can guarantee enough time accuracy even for communication interruptions of the order of one hour. The relationship between QZSS plus GPS positioning accuracy and QZSS clock quality is discussed., IGNSS2007; Sydney, Australia