Potentiality of Multi-GNSS precise point positioning time transfer with ambiguity resolution in determining gravity potential

Abstract

<p>In this study the time transfer algorithms of the precise point positioning (PPP) and integer PPP (IPPP) are extended to Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), BeiDou Navigation Satellite System (BDS) and Galileo Navigation Satellite System (Galileo). Taking BRUX-OPMT, BRUX-PTB, BRUX-WTZR, and BRUX-CEBR four-time links as an example, the performances of the PPP and the IPPP time transfer of the GPS, BDS, Galileo and GLONASS systems are compared and analyzed. The results show that the performances of GPS and Galileo are better than those of BDS and GLONASS. With an ambiguity resolution, the frequency instability in time transfer can reach sub 10<sup>-16</sup> level after five days. Compared with the PPP solutions, the long-term frequency stability of IPPP is improved by above 15% on average. If the frequency instability of the clock reaches 1 × 10<sup>-18</sup>, an equivalent altitude difference of 1.0 cm can be sensed with the help of the PPP or IPPP time transfer technique. High-precision GNSS time transfer methods, especially the IPPP time transfer techniques with their advantages in long-term stability, will provide prospective applications for determining the gravity potential, measuring height, and unifying the world height system. This study is supported by the National Natural Science Foundations of China (NSFC) under Grants 42030105, 41721003, 41804012, 41631072, 41874023, Space Station Project (2020)228, and the Natural Science Foundation of Hubei Province of China under Grant 2019CFB611.</p><p><strong>Keywords</strong>  Multi-GNSS  PPP  Ambiguity resolution  Time transfer  Gravity potential</p>