29th Annual Precise Time and Time Interval (PTTI) Meeting TIME TRANSFER USING GPS CARRIER PHASE METHODS

We have conducted several time-transfer experiments using the phase o f the GPS carrier rather than the code,as is done in current GPS-based time transfer systems. We used data from geodetic quality "off-the-shelf ' dual-frequency GPS receivers, where up to 8 satellites can be simultaneously observed. Wk connected two GPS receivers to two different atomic clocks at NIST. The antennas con-nected to the receivers were separated by about 40 m. The time difference between the clocks connected to the GPS receivers was estimated using weighted least-squares methods and carrier phase data. These relative clock estimates were then compared with the NIST time-scale system. W> find agreement between the two methods of 55-80 picoseconds over periods of a week