Investigation of real-time carrier phase time transfer using current multi-constellations

Abstract Real-time precise point positioning (RTPPP) time transfer has grown up to be a research hotspot. With the operation of IGS real-time products, multi-GNSS RTPPP time transfer has become possible. In our work, CLK93 products are applied for RTPPP time transfer, and the availability and accuracy of real-time products is evaluated over a testing period of 31 days. Then, GPS, Galileo, GLONASS and multi-GNSS RTPPP time transfer are studied and analyzed by performing a 31-day processing with 28 time-links. The results show that the availability of GPS, GLONASS and Galileo are approximately 98 %, 99 % and 99 %, respectively. The mean root mean square (RMS) values of Radial (R), Along (A) and Cross (C) direction for GPS, GLONASS and Galileo satellites are (0.025, 0.035, 0.027) m, (0.025, 0.073, 0.048) m and (0.029, 0.040, 0.035) m, respectively. The mean standard deviation (STD) values of GPS, GLONASS and Galileo satellites are (0.12, 0.38, 0.09) ns. Furthermore, Galileo RTPPP time transfer solutions perform better than GLONASS, and GPS RTPPP show performs best performance among the single-GNSS. Multi-GNSS RTPPP outperforms that of single-GNSS. The mean daily STD values of the difference between GPS, Galileo, GLONASS and multi-GNSS RTPPP solutions and IGS final products are (0.093, 0.103, 0.133, 0.083) ns, respectively. 15360 s stability is (3.87E-15, 4.56E-15, 8.61E-15, 3.73E-15) for GPS, Galileo, GLONASS and multi-GNSS RTPPP solutions at PT11-PTBB.