EUROPEAN 2-WAY SATELLITE TIME TRANSFER EXPERIMENTS USING THE INTELSAT(VA-F13) SATELLITE AT 307-DEGREES-E

A two-way satellite time and frequency transfer (TWSTFT) experiment pe rformed between six European laboratories is reported. Transfers were made on a regular basis over a period of six months. TWSTFT was demons trated to. be a useful method to compare a relatively large number of atomic clocks internationally, as an alternative to the method of comm on view of global positioning system (GPS) satellites. The GPS common view time transfer method and TWSTFT method were compared over the sam e link for a period of 150 days. Three TWSTFT's have been performed si multaneously. Time transfers were performed over periods of up to 8 h, enabling the measurement noise of the TWSTFT system and the stability of the atomic clocks to be examined. Time transfers were made in cons ecutive successions between clocks at three distant earth stations. Cl osing errors of up to approximately 4 ns were observed. The magnitude of these dosing errors justified further examination. The uncertaintie s in the determination of the closing errors have been examined along with their origin, characteristics, and dependence on operating parame ters.