A new technique for estimating frequency from GPS carrier-phase time transfer data

Abstract

GPS carrier-phase time transfer (GPSCPTT) offers good frequency stability at short averaging times, approaching a fractional frequency stability of 10/sup -15/ at an averaging time of 1 d. However, a discontinuity occurs in the time transfer estimates between the end of one processing batch (typically 1-3 d in length) and the beginning of the next. We present a new technique in which a frequency is computed from each batch solution and then these frequency values are averaged to obtain a mean frequency for the epoch of interest. The advantages of the new technique are (a) robustness in the event of a data outage and (b) the ability to compute frequency in the absence of the uncertainty introduced by the removal of the discontinuities. The frequency values obtained from the GPSCPTT data using the new method agreed with those obtained using the conventional method at 2-3/spl middot/10/sup -16/, thus, it may be feasible to replace the conventional method with the new one.