Results of the Time Comparison Experiments Between the QZS-1 and Ground Time Management Station

The time management system of the first Quasi-Zenith Satellite (QZS-1), which consisted of on-board time transfer subsystem (TTS) and related ground systems such as time management stations (TMS) was developed by National Institute of Information and Communications Technology, Japan (NICT). TTS measures the time differences between an on-board Rb clock and an atomic clock of the TMS. TTS also measures the time differences between the on-board Rb clocks and the satellite reference clock, moreover between the L-band signals and the satellite reference clock. In the time comparison experiments between the QZS-1 and TMSs, we achieved the measurement precision about 40 picoseconds and the stability about 8x10-14 at an averaging time of 1000 seconds. Time comparison results were confirmed the consistency with the two-way satellite time comparison using a communication satellite and the clock estimation using ephemeris respectively, in better stability.