TY  - JOUR
A1  - Tu, Rui
A1  - Wang, L.
A1  - Liu, Z.
T1  - Real time monitoring ground motion using GPS with real time corrections
JF  - Survey Review
N2  - The high rate GPS velocity determination technology which is based on the broadcast ephemeris and epoch differenced model can retrieve displacement of ground motion with the precision of a few centimetres to decimetres in real time. Moreover, the precision of the recovered displacement can be improved if the un-modelled errors such as broadcast ephemeris residuals, atmospheric residuals, multipath effects and high frequency noise are tackled more accurately. In this paper, we propose a method to improve the precision of the recovered displacement by appropriately making use of reference station corrections. For the reference stations, the coordinates are highly constrained to extract the error corrections that are to be broadcast via a communication link to the rover. After correcting the rover’s observations, some errors such as ephemeris residuals and atmospheric residuals are effectively eliminated or at least reduced. This improves the accuracy of the observations and thus enhances the reliability of the velocity estimation. The displacement can be recovered by integrating the estimated velocity after de-trending using a linear trend that is caused by the un-corrected residuals. The series of validation results in the experiment have shown that the displacement of the simulated motion can be real time recovered with a precision of 1–2 cm, and is thus applicable for real time monitoring of the ground motion.
KW  - Real time
KW  - High rate GPS
KW  - Strong motion
KW  - Reference station
KW  - Rover station
Y1  - 2016
U6  - https://doi.org/10.1179/1752270614Y.0000000141
SN  - 0039-6265
SN  - 1752-2706
VL  - 48
SP  - 79
EP  - 85
PB  - Wiley
CY  - Abingdon
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  -