Abstract:
Objectives The BeiDou-3 satellite navigation system (BDS-3) can provide real-time precise point positioning (PPP) services to China and neighboring regions through PPP-B2b signals. Because PPP-B2b signals do not contain ionospheric model products, the current positioning research mainly adopts ionospheric-free combination. The positioning accuracy can reach decimeter level, but requires about 30 min of convergence time. In this paper, aiming at the long convergence time of PPP-B2b positioning, the improvement of positioning convergence performance based on ionospheric model products is analyzed.
Methods Quasi-4-dimensional ionospheric modeling is introduced into regional ionospheric delay modeling in China and four schemes of 50,100,150 and 200 reference stations uniformly distributed in China (day of year 201—207) are adopted for ionospheric modeling.
Results The results show that when the number of stations used in ionospheric modeling increases from 50 to 200, the accuracy of ionospheric model products increases from 2-3 TECU to better than 0.8 TECU. Compared with the current ionospheric-free combined PPP, the convergence time of BDS-3 dynamic PPP can be deceased by 77%. In addition, the convergence time of GPS+BDS-3 dynamic PPP is reduced from 13.51 min to 4.45 min.
Conclusions High-precision ionospheric model products can significantly shorten the convergence time of PPP-B2b.
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