Abstract
Nowadays, China BeiDou Navigation Satellite System (BDS) has been developed well and provided global services with highly precise positioning, navigation and timing (PNT) as well as unique short-message communication, particularly global system (BDS-3) with higher precision multi-frequency signals. The precise point positioning (PPP) can provide the precise position, receiver clock, and zenith tropospheric delay (ZTD) with a stand-alone receiver compared to the traditional double differenced relative positioning mode, which has been widely used in PNT, geodesy, meteorology and so on. However, it has a lot of challenges for multi-frequency BDS PPP with different strategies and more unknown parameters. In this paper, the detailed PPP models using the single-, dual-, triple-, and quad-frequency BDS observations are presented and evaluated. Firstly, BDS system and PPP method are introduced. Secondly, the stochastic models of time delay bias in BDS-2/BDS-3 PPP including the neglection, random constant, random walk and white noise are presented. Then, three single-frequency, four dual-frequency, four triple-frequency and four quad-frequency BDS PPP models are provided. Finally, the BDS PPP models progress and performances including theoretical comparison of the models, positioning performances, precise time and frequency transfer, ZTD, inter-frequency bias (IFB) and differential code bias (DCB) are presented and evaluated as well as future challenges. The results show that the multi-frequency BDS observations will greatly improve the PPP performances.
Highlights
Global Positioning System (GPS) has been widely used in positioning, navigation, timing (PNT) services and sciences related to positioning on Earth’s surface with an unprecedented high precision and accuracy, since it became full operation in 1993 (Jin et al 2011)
The stochastic models of time delay bias (TDB) in BeiDou Navigation Satellite System (BDS)-2/BDS-3 precise point positioning (PPP) are showed in the third section
Some processing strategies can be applied for BDS-2 and BDS-3 combined PPP solutions and the corresponding TDB stochastic models can be expressed as follows
Summary
Global Positioning System (GPS) has been widely used in positioning, navigation, timing (PNT) services and sciences related to positioning on Earth’s surface with an unprecedented high precision and accuracy, since it became full operation in 1993 (Jin et al 2011). The stochastic models of time delay bias (TDB) in BDS-2/BDS-3 PPP are showed in the third section. Some processing strategies can be applied for BDS-2 and BDS-3 combined PPP solutions and the corresponding TDB stochastic models can be expressed as follows. Neglection The neglection of TDB parameters in BDS PPP will change the estimable parameters including receiver clock and carrier phase ambiguities This operation will apply the BDS-2 and BDS-3 observations to one common system. BDS PPP models Figure 2 shows the multipath combination (MPC) amplitudes for the BDS C01, C06, C12, C19 and C20 satellites, representing the BDS-2 GEO, BDS-2 IGSO, BDS-2 MEO, BDS-3 MEO and BDS-3 MEO, respectively, observed at station XIA3 during the DOY 9–14, 2019 from international GNSS Monitoring and Assessment System (iGMAS) (http://www.igmas.org). Ionosphere‐constrained single‐frequency PPP Adding virtual ionospheric observations from the external ionospheric model such as global ionospheric maps (GIMs), the ionosphere-constrained single-frequency PPP (SF3) model can be described as (Gao et al 2017):
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