Abstract
For single-frequency Global Navigation Satellite Systems (GNSSs) users, ionospheric delay is the main error source affecting the accuracy of positioning. Applying a broadcast ionospheric correction model to mitigate the ionospheric delay is essential for meter-to-decimeter-level accuracy positioning. To provide support for real-time single-frequency operations, particularly in the China area, we assessed the performance of three broadcast ionospheric correction models, namely, the Neustrelitz total electron content (TEC) broadcast model (NTCM-BC), the BeiDou global broadcast ionospheric delay correction model (BDGIM), and the Klobuchar model. In this study, the broadcast coefficients of Klobuchar and BDGIM are obtained from the navigation data files directly. Two sets of coefficients of NTCM-BC for China and global areas are estimated. The slant total electron contents (STEC) data from more than 80 validation stations and the final vertical TEC (VTEC) data of the Center for Orbit Determination in Europe (CODE) are used as independent benchmarks for comparison. Compared to GPS STEC during the period of Day of Year (DOY) 101~199, 2019, the ionospheric correction ratio of NTCM-BC, BDGIM, and Klobuchar are 79.4%, 64.9%, and 57.7% in China, respectively. For the global area, the root-mean-square (RMS) errors of these three models are 3.67 TECU (1 TECU = 1016 electrons/m2), 5.48 TECU, and 8.92 TECU, respectively. Compared to CODE VTEC in the same period, NTCM-BC, BDGIM, and Klobuchar can correct 72.6%, 69.8%, and 61.7% of ionospheric delay, respectively. Hence, NTCM-BC is recommended for use as the broadcast ionospheric model for the new-generation BeiDou satellite navigation system (BDS) and its satellite-based augmentation system.
Highlights
Global Navigation Satellite Systems (GNSSs) mainly utilize radio waves to realize navigation, positioning, timing, and other functions
Where a0,j ak,j and bk,j are the non-broadcast parameters of BDGIM, the values of which can be seen in BeiDou satellite navigation system (BDS) interface control document (ICD) [6], Tk is the period for each non-broadcast coefficient, and Tp denotes the odd hour of the one day (01:00:00, 03:00:00, 05:00:00, . . . , 23:00:00 in Modified Julian Date (MJD)) [6]
This study compares the performance of the NTCM‐BC, BDGIM, and Klobuchar model over both China and a global area, aiming to seek a better broadcast ionospheric model for the BDS and its augmentation system
Summary
Global Navigation Satellite Systems (GNSSs) mainly utilize radio waves to realize navigation, positioning, timing, and other functions. As for the BeiDou satellite navigation system (BDS), the regional BeiDou (BDS-2) broadcasts eight parameters and uses a slightly modified Klobuchar model (BDSKlobuchar) to calculate ionospheric delay. It is almost the same as the Klobuchar model except for the reference frame and the update frequency of parameters. Hoque et al argue that NTCM-BC is an alternative solution for the next-generation GNSSs, its superiority with respect to BDGIM for the global BDS-3 satellites as well as its augmentation service around China have not been validated. We build two NTCM-BC models with the regional and global station data and make a comprehensive comparison and evaluation with Klobuchar and BDGIM, aiming to seek a better model for BDS and its augmentation system.
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