Abstract
The present Global Navigation Satellite System (GNSS) can provide at least double-frequency observations, and especially the Galileo Navigation Satellite System (Galileo) can provide five-frequency observations for all constellation satellites. In this contribution, precision point positioning (PPP) models with Galileo E1, E5a, E5b, E5 and E6 frequency observations are established, including a dual-frequency (DF) ionospheric-free (IF) combination model, triple-frequency (TF) IF combination model, quad-frequency (QF) IF combination model, four five-frequency (FF) IF com-bination models and an FF uncombined (UC) model. The observation data of five stations for seven days are selected from the multi-GNSS experiment (MGEX) network, forming four time-frequency links ranging from 454.6 km to 5991.2 km. The positioning and time-frequency transfer performances of Galileo multi-frequency PPP are compared and evaluated using GBM (which denotes precise satellite orbit and clock bias products provided by Geo Forschung Zentrum (GFZ)), WUM (which denotes precise satellite orbit and clock bias products provided by Wuhan University (WHU)) and GRG (which denotes precise satellite orbit and clock bias products provided by the Centre National d’Etudes Spatiales (CNES)) precise products. The results show that the performances of the DF, TF, QF and FF PPP models are basically the same, the frequency stabilities of most links can reach sub10−16 level at 120,000 s, and the average three-dimensional (3D) root mean square (RMS) of position and average frequency stability (120,000 s) can reach 1.82 cm and 1.18 × 10−15, respectively. The differences of 3D RMS among all models are within 0.17 cm, and the differences in frequency stabilities (in 120,000 s) among all models are within 0.08 × 10−15. Using the GRG precise product, the solution performance is slightly better than that of the GBM or WUM precise product, the average 3D RMS values obtained using the WUM and GRG precise products are 1.85 cm and 1.77 cm, respectively, and the average frequency stabilities at 120,000 s can reach 1.13 × 10−15 and 1.06 × 10−15, respectively.
Highlights
Tu et al [18] studied the performance of real-time kinematics (RTK) using Galileo fourfrequency observations, and the results showed that multiple frequencies were much better than single-frequency, and the coordinates’ standard deviation (STD) was improved by approximately 30%
Liu et al [23] used the phase bias product provided by CNES to test triple-frequency Global Positioning System (GPS)/Galileo RT precision point positioning (PPP) ambiguity resolution (AR) and proved that triple-frequency PPP AR can improve the convergence time performance and positioning accuracy compared with dual-frequency PPP AR
Based on the evaluation the multipath combination noise of Galileo multi-frequency observations, the convergence time and positioning accuracy of DF, TF, QF and FF models were evaluated by using precision products of different Analysis Centers (ACs), and the performance of time-frequency transfer of Galileo E1, E5a, E5b, E5 and E6 multi frequency signals is compared and analyzed systematically for the first time
Summary
Liu et al [23] used the phase bias product provided by CNES to test triple-frequency GPS/Galileo RT PPP AR and proved that triple-frequency PPP AR can improve the convergence time performance and positioning accuracy compared with dual-frequency PPP AR. Based on the evaluation the multipath combination noise of Galileo multi-frequency observations, the convergence time and positioning accuracy of DF, TF, QF and FF models were evaluated by using precision products of different ACs, and the performance of time-frequency transfer of Galileo E1, E5a, E5b, E5 and E6 multi frequency signals is compared and analyzed systematically for the first time. National d’Etudes Spatiales (CNES)) precise products to evaluate the positioning and the time-frequency transfer performance results of the Galileo DF, TF, QF, and FF PPP models.
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