Performance Analysis of GPS at Three Ephemerides on Medium and Long Baselines

With the continuous improvement and updating of GPS technologies, medium and long baselines are widely used in GPS data processing. Currently, the International GPS Geodynamic Service Center (IGS) provides the final precise ephemeris (IGSF), rapid precise ephemeris (IGR) and ultrarapid precise ephemeris (IGU). These three different precise ephemerides are different in terms of accuracy and update frequency, and have different effects on the accuracy of the baseline solution in practical applications. Therefore, in order to analyze the influence of the published accuracy of these three ephemerides on the results of the baseline solution. Based on 7-day observation files and their corresponding ephemeris files, this study uses Trimble Business Center (TBC) 5.2 software to perform the baseline solution with three different ephemeris files. We take the baseline result of the IGSF solution as the true value, and compare the baseline results of the other two ephemeris solutions. There are specific discussions about baseline length within 200 km, 500 km–1300 km and 1300 km–2600 km. Results show that when the baseline length is 1300 km–2600 km, the 7-day average of the difference of ΔX, ΔY and ΔZ of IGR-IGSF are all less than 1.19 mm, while IGU-IGSF are all less than 8.64 mm. In terms of root mean square, the 7-day average accuracy in the X, Y, and Z directions of the TBC equipped with IGSF is less than 11.76 mm, while the equipped IGU is less than 12.94 mm. Therefore, in the solution of medium and long baselines, the final precise ephemeris and the rapid precise ephemeris have higher accuracy, and the ultrarapid precise ephemeris is less accurate. When the final precise ephemeris is not acquired in time, the fast precise ephemeris can be used for the baseline solution.