Toward 10-15 and sub-nanosecond international frequency and time metrology [using GPS advanced common-view]

We have investigated a relatively simple, GPS-based, time comparison system described as “Advanced common-view” using modular GPS receivers. The results of preliminary experiments over short baselines indicate a very low instrumental noise level, and a one-day stability of about 0.3 nanoseconds. The experiments are being extended to longer baselines. If this stability is reproducibly obtained, or even improved, the technique could be used to improve the quality of the data used to determine TAI and UTC. Since the method is easily automated and rapid, it might be useful in implementing real-time UTC