Continuous, multi-channel, common-view, L1-GPS time-comparison over a 4,000 km baseline

We are investigating a method of time comparison described as “Advanced Common-View GPS” or GPS-ACV. This is a technique that uses the largest possible number of observations on all satellites in common-view to average short-term noise and reduce the effect of errors. The goal is to make optimum use of all degrees of freedom afforded by the data. We have recently tested the ACV method over a 4,000 km baseline using inexpensive, single-frequency, modular GPS receivers. The results indicate that a measurement noise of less than 1 nanosecond can be obtained for averaging times of 1 and 2 days. The equivalent uncertainty for frequency transfer is below 10^-14