Estimation and Analysis of BDS2 and BDS3 Differential Code Biases and Global Ionospheric Maps Using BDS Observations

Following the continuous and stable regional service of BDS2, BDS3 officially announced its global in July 2020. To fully take advantage new multi-frequency signals ionosphere sensing positioning, it is essential to understand characteristics differential code bias (DCB) BDS performance ionospheric maps (GIMs) estimation. This article presents an evaluation 13 types DCBs accuracy BDS-based GIM based on data provided by International GNSS Service (IGS) Monitoring Assessment System (iGMAS) for first time. The GIMs are estimated APM (Innovation Academy Precision Measurement Science Technology) method a time efficient manner, which can be divided into two main steps. step produce observations at B1I, B2I B3I signals, second estimate among other frequency bands removing delay using precomputed GIMs. Good agreement found between APM-based satellite DCB estimates those from Chinese Sciences (CAS) German Aerospace Center (DLR) levels 0.26 ns 0.18 ns, respectively. results, spanning one month, show that stability different related contributed observations, receiver represent larger STD values than estimates. differences BDS2 receivers antennas firmware version, JAVAD reaches 1.03 ns. results also indicate difference single-frequency standpoint positioning (SPP) GPS-based corrections less 0.03 m both horizontal vertical directions.