Measurement ( IF 3.364 ) Pub Date : 2020-10-16 , DOI: 10.1016/j.measurement.2020.108597 Mingjun Ouyang; Junzhi Li; Wanqing Li; Yulong Ge; Xiangwei Zhu; Zhengkun Chen; Zhiqiang Dai
The PPP(precise point positioning) has a quite long convergence time at the beginning of the positioning process or the scene that real-time data was interrupted to resume, and the positioning accuracy during the convergence period does not meet the requirements of high-precision applications. This paper studies the PPP method for time transfer and its accuracy and stability during the convergence time. Based on study the correlation between clock difference, coordinates and tropospheric parameters, the method of fixing coordinates was proposed. By the application of prior coordinate information, compared to the conventional method, with 83 stations, RMS(Root Mean Square) of clock improved range from 2.23% to 98.51% and STD (Standard Deviation) improved range from 10.13% to 92.56%; also, the time transfer accuracy was below 1 ns during the convergence period. When the modified Allan variance was adopted, the frequency stability of clock improved range from 0.55% to 30.28%, and improved up to 67.43%, which verified the improvement of frequency stability during the convergence period when prior information on coordinate was used.