TY  - JOUR
A1  - Tu, Rui
A1  - Ge, Maorong
A1  - Zhang, Hongping
A1  - Huang, Guanwen
T1  - The realization and convergence analysis of combined PPP based on raw observation
JF  - Advances in space research
N2  - In order to speed up Precise Point Positioning (PPP)'s convergence, a combined PPP method with GPS and GLONASS which is based on using raw observations is proposed, and the positioning results and convergence time have been compared with that of single system. The ionospheric delays and receiver's Differential Code Bias (DCB) corrections are estimated as unknown parameters in this method. The numerical results show that the combined PPP has not caused significant impacts on the final solutions, but it greatly improved Position Dilution of Precision (PDOP) and convergence speed and enhanced the reliability of the solution. Meanwhile, the convergence speed is greatly influenced by the receiver's DCB, positioning results in horizontal which are better than 10 cm can be realized within 10 min. In addition, the ionosphere and DCB products can be provided with high precision.
KW  - GPS and GLONASS
KW  - Precise Point Positioning
KW  - Raw observation
KW  - DCB
KW  - Combine
Y1  - 2013
U6  - https://doi.org/10.1016/j.asr.2013.03.005
SN  - 0273-1177
VL  - 52
IS  - 1
SP  - 211
EP  - 221
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Tu, Rui
A1  - Zhang, Hongping
A1  - Ge, Maorong
A1  - Huang, Guanwen
T1  - A real-time ionospheric model based on GNSS Precise Point Positioning
JF  - Advances in space research
N2  - This paper proposes a method of real-time monitoring and modeling the ionospheric Total Electron Content (TEC) by Precise Point Positioning (PPP). Firstly, the ionospheric TEC and receiver's Differential Code Biases (DCB) are estimated with the undifferenced raw observation in real-time, then the ionospheric TEC model is established based on the Single Layer Model (SLM) assumption and the recovered ionospheric TEC. In this study, phase observations with high precision are directly used instead of phase smoothed code observations. In addition, the DCB estimation is separated from the establishment of the ionospheric model which will limit the impacts of the SLM assumption impacts. The ionospheric model is established at every epoch for real time application. The method is validated with three different GNSS networks on a local, regional, and global basis. The results show that the method is feasible and effective, the real-time ionosphere and DCB results are very consistent with the IGS final products, with a bias of 1-2 TECU and 0.4 ns respectively.
KW  - Ionospheric monitoring and modeling
KW  - Precise Point Positioning (PPP)
KW  - Real time
KW  - Total Electron Content (TEC)
KW  - Global Navigation Satellite System (GNSS)
KW  - Differential Code Biases (DCB)
Y1  - 2013
U6  - https://doi.org/10.1016/j.asr.2013.06.015
SN  - 0273-1177
SN  - 1879-1948
VL  - 52
IS  - 6
SP  - 1125
EP  - 1134
PB  - Elsevier
CY  - Oxford
ER  -