Abstract
Following the continuous and stable regional service of BDS2, the BDS3 officially announced its global service in July 2020. To fully take advantage of the new multi-frequency BDS3 signals in ionosphere sensing and positioning, it is essential to understand the characteristics of the differential code bias (DCB) of new BDS3 signals and BDS performance in global ionospheric maps (GIMs) estimation. This article presents an evaluation of the characteristics of 13 types of BDS DCBs and the accuracy of BDS-based GIM based on the data provided by the International GNSS Service (IGS) and International GNSS Monitoring and Assessment System (iGMAS) for the first time. The GIMs and DCBs are estimated by the APM (Innovation Academy for Precision Measurement Science and Technology) method in a time efficient manner, which can be divided into two main steps. The first step is to produce GIMs based on BDS observations at the B1I, B2I and B3I signals, and the second step is to estimate DCBs among the other frequency bands by removing the ionospheric delay using the precomputed GIMs. Good agreement is found between the APM-based satellite DCB estimates and those from the Chinese Academy of Sciences (CAS) and the German Aerospace Center (DLR) at levels of 0.26 ns and 0.18 ns, respectively. The results, spanning one month, show that the stability of BDS DCB estimates among different frequency bands are related to the contributed observations, and the receiver DCB estimates represent larger STD values than the satellite DCB estimates. The differences in receiver DCB estimates between BDS2 and BDS3 are found to be related to the types of receivers and antennas and firmware version, and the bias of the JAVAD receivers reaches 1.03 ns. The results also indicate that the difference in the single-frequency standpoint positioning (SPP) accuracy using GPS-based and BDS-based GIMs for ionospheric delay corrections is less than 0.03 m in both the horizontal and vertical directions.
Highlights
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland.As the third global navigation satellite system (GNSS) following the great successes of the GPS and GLONASS systems, the BeiDou navigation satellite system (BDS) has evolved from a regional navigation satellite system (BDS2) to the third generation of the navigation satellite system (BDS3) with global coverage [1]
The performance of the global ionospheric maps (GIMs) estimated with only BDS data is analyzed
This article provides an analysis of satellite and receiver differential code bias (DCB) among different frequency bands for BDS2 and BDS3, and an overview of the performance assessment of GIMs produced only by BDS observables for the first time
Summary
As the third global navigation satellite system (GNSS) following the great successes of the GPS and GLONASS systems, the BeiDou navigation satellite system (BDS) has evolved from a regional navigation satellite system (BDS2) to the third generation of the navigation satellite system (BDS3) with global coverage [1]. The BDS2 has provided services mainly in the Asia-Pacific area since 27 December 2012.The completion of BDS3 was officially announced on 31 July 2020, after which BDS3 started to provide services at its full operational capability, including positioning, timing and short message communications [1]. BDS2 currently consists of three medium earth orbit (MEO) satellites, five geostationary earth orbit (GEO) satellites and seven inclined geosynchronous orbit (IGSO) satellites. By June 2020, the BDS3 system consisted of three
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