An Improvement of RINEX-Shift Algorithm for Continuous GPS Carrier-Phase Time Transfer
Jian Yao, Judah Levine
The wide application of GPS carrier-phase (CP) time transfer is limited by the problem of boundary discontinuity. The RINEX-Shift (RS) algorithm was designed to solve this problem. However, if there are GPS data anomalies, the time transfer result computed by this algorithm oscillates around the true value. The deviation from the true value could be as big as a few nanoseconds. The origin of this oscillation behavior lies in the fact that PPP needs some time (e.g., a couple of hours) to converge. If there are only a short term of valid data before or after the missing data, PPP does not have enough time to converge so that the solution for this short term has a big oscillation around the true value. We propose the "revised RINEX-Shift" (RRS) algorithm to solve the oscillation problem in the RS algorithm. RRS extracts the result at the middle epoch, rather than the first epoch as in the RS algorithm. In this way, PPP has enough time to converge. Tests show that the oscillation problem is solved successfully and there is a 10-55% improvement of fractional frequency stability. Thus, the RRS algorithm provides the best GPS time transfer result.
Proceedings of ION GNSS+ 2014 Conference
September 8-12, 2014
ION GNSS+ 2014 Conference
boundary discontinuity, carrier phase, GPS, isolated island effect, precise point positioning, Revised RINEX-Shift algorithm, RINEX-Shift algorithm, time transfer