Real-Time BDS-3 Clock Estimation with a Multi-Frequency Uncombined Model including New B1C/B2a Signals

Kaifa Kuang,Jian Wang,Houzeng Han

doi:10.3390/rs14040966

Kaifa Kuang, Jian Wang + Show 1 more

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https://doi.org/10.3390/rs14040966

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Abstract

The global system of BDS (BeiDou Navigation Satellite System), i.e., BDS-3, is characterized with a multi-frequency signal broadcasting capability, which was demonstrated as beneficial for GNSS (Global Navigation Satellite System) data processing. However, research on real-time BDS-3 clock estimation with multi-frequency signals is quite limited, especially for the new B1C and B2a signals. In this study, we developed models for BDS-3 multi-frequency real-time data processing, including the uncombined model for clock estimation and the GFIF (Geometry-Free Ionosphere-Free) combined model for IFCB (Inter-Frequency Clock Bias) determination. Based on the models, simulated real-time numerical experiments with about 80 global IGS (International GNSS Service) network stations are conducted for validation and analysis. The results indicate that: (1) the uncombined model with multi-frequency signals can achieve comparable accuracy with the traditional dual-frequency IF model in terms of clock estimation, and the double-differenced clock STDs (Standard Deviations) are generally less than 0.05 ns with post-processed clocks as a reference; (2) unlike the B1C and B1I/B3I signals, the satellite IFCBs generated from multi-frequency clock estimation show apparent temporal variations for B2a and B1I/B3I signals, further investigation with GFIF models confirm the variations mainly result from the errors of receiver antenna corrections. Therefore, we addressed the feasibility of the uncombined model and the importance of accurate antenna information in the multi-frequency data processing.

Highlights

Real-time GNSS (Global Navigation Satellite System) applications with the PPP (Precise Point Positioning) technique call for corresponding high-quality satellite orbit and clock solutions
Signals, the satellite IFCBs generated from multi-frequency clock estimation show apparent temporal variations for B2a and B1I/B3I signals, further investigation with GFIF models confirm the variations mainly result from the errors of receiver antenna corrections
To validate the developed models for real-time BDS-3 clock and IFCB estimation, RINEX3 (Receiver INdependent EXchange format 3) observation data from about 80 globally distributed IGS network stations (Figure 2) spanning 1 April to 8 April 2021 are used for the simulated real-time numerical experiments

Summary

Introduction

Real-time GNSS (Global Navigation Satellite System) applications with the PPP (Precise Point Positioning) technique call for corresponding high-quality satellite orbit and clock solutions. Service) started providing real-time GNSS orbit and clock products with the RTS To improve the accuracy and efficiency of real-time clock solutions, research has been devoted to various aspects during the past decades, including estimation models [3,4], processing efficiency [5,6] and quality control [7]. While the traditional clock estimation usually incorporates dual-frequency signals with an IF (Ionosphere-Free) combination, the situation becomes different with the evolving of GNSS constellations. With the modernization of GPS (Global Positioning System) and GLONASS (GLObal NAvigation Satellite System) constellations and development of BDS (BeiDou Navigation Satellite System) and Galileo constellations, increasing satellites, including GPS block IIF and IIIA satellites, part of GLONASS-M and all GLONASS-K satellites, and all Galileo and BDS satellites, are broadcasting multi-frequency signals

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