Common-clock two-way satellite time transfer experiments

We report the results of a series of measurements designed to determine the magnitudes and noise types of the various sources of instability in the two-way satellite time and frequency transfer (TWSTFT) process. We find that, for our equipment, the earth-station noise predominates at the 1 day time scale. We also report results from a maser-to-maser time transfer conducted between NIST-Boulder and USNO (Washington DC), which show a stability at 1 day of about 1 ns.