Performance of Multi-GNSS Precise Point Positioning Time and Frequency Transfer with Clock Modeling

Abstract

Thanks to the international GNSS service (IGS), which has provided multi-GNSS precise products, multi-GNSS precise point positioning (PPP) time and frequency transfer has of great interest in the timing community. Currently, multi-GNSS PPP time transfer is not investigated with different precise products. In addition, the correlation of the receiver clock offsets between adjacent epochs has not been studied in multi-GNSS PPP. In this work, multi-GNSS PPP time and frequency with different precise products is first compared in detail. A receiver clock offset model, considering the correlation of the receiver clock offsets between adjacent epochs using an a priori value, is then employed to improve multi-GNSS PPP time and frequency (scheme2). Our numerical analysis clarify how the approach performs for multi-GNSS PPP time and frequency transfer. Based on two commonly used multi-GNSS products and six GNSS stations, three conclusions are obtained straightforwardly. First, the GPS-only, Galileo-only, and multi-GNSS PPP solutions show similar performances using GBM and COD products, while BDS-only PPP using GBM products is better than that using COD products. Second, multi-GNSS time transfer outperforms single GNSS by increasing the number of available satellites and improving the time dilution of precision. For single-system and multi-GNSS PPP with GBM products, the maximum improvement in root mean square (RMS) values for multi-GNSS solutions are up to 7.4%, 94.0%, and 57.3% compared to GPS-only, BDS-only, and Galileo-only solutions, respectively. For stability, the maximum improvement of multi-GNSS is 20.3%, 84%, and 45.4% compared to GPS-only, BDS-only and Galileo-only solutions. Third, our approach contains less noise compared to the solutions with the white noise model, both for the single-system model and the multi-GNSS model. The RMS values of our approach are improved by 37.8-91.9%, 10.5-65.8%, 2.7-43.1%, and 26.6-86.0% for GPS-only, BDS-only, Galileo-only, and multi-GNSS solutions. For frequency stability, the improvement of scheme2 ranges from 0.2 to 51.6%, from 3 to 80.0%, from 0.2 to 70.8%, and from 0.1 to 51.5% for GPS-only, BDS-only, Galileo-only, and multi-GNSS PPP solutions compared to the solutions with the white noise model in the Eurasia links.

Virtual Antenna Array for Minimization of DOA Estimation Systematic Error Caused by Scattering of Incident Waves on Antenna Carrier Body

“…The aim of many recent studies is to increase the positioning accuracy of Global Navigation Satellite Systems (GNSS) by use of the Precise Point Positioning (PPP) technique. The authors of [30] compared a multi-GNSS PPP time and frequency transfer with different precise products. To improve multi-GNSS PPP time and frequency, they suggest employong a receiver clock offset model, considering the correlation of the receiver clock offsets between adjacent epochs using an a priori value.…”

The Benefits of Receiver Clock Modelling in Satellite Timing

“…In 2013, Wang et al [ 11 ] demonstrated the feasibility of the stochastic clock parameter with constrained variance in subsequent epochs, and the extent of the improvement was different for different types of atomic clocks. In 2018, Ge et al [ 12 , 13 ] contributed the receiver clock offset model considering the correlation of the receiver clock offsets among adjacent epochs using an a priori value, which is suitable for single GNSS and multiple GNSS. In 2014, Lyu et al [ 14 ] achieved covariance with white frequency modulation (WFM) noise, random walk frequency modulation (RWFM) noise and the correlation between the clock and ambiguity parameter and obtained better results in mitigating day boundaries.…”

Development of Global Tropospheric Empirical Correction Model with High Temporal Resolution

“…As it is hard to obtain meteorological parameters because of the economic cost, the initial value of tropospheric delay is normally determined based on standard atmospheric parameters [11][12][13][14]; however, as the results obtained have a lower accuracy, a longer convergence period is always required for GNSS positioning. With the increasing application of PPP [15][16][17][18][19], in order to improve the convergence speed of PPP [20,21], the accuracy of the troposphere model needs to be higher.…”