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On Modelling of Second-Order Ionospheric Delay for GPS Precise Point Positioning

Published online by Cambridge University Press:  25 November 2011

Mohamed Elsobeiey  and
Ahmed El-Rabbany
Mohamed Elsobeiey
Affiliation:
(Department of Civil Engineering, Ryerson University, 350 Victoria Street, Toronto, CanadaM5B 2K3)
Ahmed El-Rabbany*
Affiliation:
(Department of Civil Engineering, Ryerson University, 350 Victoria Street, Toronto, CanadaM5B 2K3)
*
(E-mail: rabbany@ryerson.ca)
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Abstract

Recent developments in GPS positioning show that a user with a standalone GPS receiver can obtain positioning accuracy comparable to that of carrier-phase-based differential positioning. Such technique is commonly known as Precise Point Positioning (PPP). A significant challenge of PPP, however, is that about 30 minutes or more is required to achieve centimetre to decimetre-level accuracy. This relatively long convergence time is a result of the un-modelled GPS residual errors. A major residual error component, which affects the convergence of PPP solution, is higher-order Ionospheric Delay (IONO). In this paper, we rigorously model the second-order IONO, which represents the bulk of higher-order IONO, for PPP applications. Firstly, raw GPS measurements from a global cluster of International GNSS Service (IGS) stations are corrected for the effect of second-order IONO. The corrected data sets are then used as input to the Bernese GPS software to estimate the precise orbit, satellite clock corrections, and Global Ionospheric Maps (GIMs). It is shown that the effect of second-order IONO on GPS satellite orbit ranges from 1·5 to 24·7 mm in radial, 2·7 to 18·6 mm in along-track, and 3·2 to 15·9 mm in cross-track directions, respectively. GPS satellite clock corrections, on the other hand, showed a difference of up to 0·067 ns. GIMs showed a difference up to 4·28 Total Electron Content Units (TECU) in the absolute sense and an improvement of about 11% in the Root Mean Square (RMS). The estimated precise orbit clock corrections have been used in all of our PPP trials. NRCan's GPSPace software was modified to accept the second-order ionospheric corrections. To examine the effect of the second-order IONO on the PPP solution, new data sets from several IGS stations were processed using the modified GPSPace software. It is shown that accounting for the second-order IONO improved the PPP solution convergence time by about 15% and improved the accuracy estimation by 3 mm.

Keywords

GPSPrecise Point PositioningSatellite OrbitClock CorrectionsIonosphere
Type
Research Article
Information
The Journal of Navigation , Volume 65 , Issue 1 , January 2012 , pp. 59 - 72
Copyright
Copyright © The Royal Institute of Navigation 2011

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References

REFERENCES

Bassiri, S. and Hajj, G. (1993). High-order ionospheric effects on the global positioning system observables and means of modeling them, Manuscr. Geod., 18, 280–289.Google Scholar
Dach, R., Hugentobler, U., Fridez, P. and Meindl, M. (2007). Bernese GPS Software Version 5.0. Astronomical Institute, University of Berne, Switzerland.Google Scholar
Gutman, S., Fuller-Rowell, T. and Robinson, D. (2003). Using NOAA Atmospheric Models to Improve Ionospheric and Tropospheric Corrections. U.S. Coast Guard DGPS Symposium, Portsmouth, VA.Google Scholar
Hernández-Pajares, M., Juan, J. M., Sanz, J. and Orús, R. (2007). Second-order Ionospheric Term in GPS: Implementation and Impact on Geodetic Estimates. Journal of Geophysical Research, 112, B08417.CrossRefGoogle Scholar
Hofmann-Wellenhof, B., Lichtenegger, H. and Walse, E. (2008). GNSS Global Navigation Satellite Systems; GPS, Glonass, Galileo & More. Springer Wien, New York.Google Scholar
Hoque, M. and Jakowski, N. (2007). Higher order ionospheric effects in precise GNSS positioning. Journal of Geodesy, 81, 259–268.CrossRefGoogle Scholar
Hoque, M. and Jakowski, N. (2008). Mitigation of higher order ionospheric effects on GNSS users in Europe. GPS Solutions, 12–2, 87–97.CrossRefGoogle Scholar
Houghton, J. T., Rycroft, M. J. and Dessler, A. J. (1998). Physics of the Space Environment. Cambridge University Press, 1998.Google Scholar
Leick, A. (2004). GPS Satellite Surveying. 3rd edition, John Wiley and Sons.Google Scholar
Lutz, S., Schaer, S., Meindl, M., Dach, R. and Steigenberger, P. (2010). Higher-order Ionosphere Modeling for CODE's Next Reprocessing Activities. Proceedings of the IGS Analysis Centre Workshop, Newcastle upon Tyne, England.Google Scholar
Merrill, R. T. and McElhinny, M. W. (1983). The Earth's Magnetic Field, its History, Origin and Planetary Perspective. International Geophysics series, Volume 32. Academic Press Inc., 1983.Google Scholar
National Oceanic and Atmospheric Administration (NOAA) website. http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html. Accessed June 2010.Google Scholar
Rowell, T. F. (2005). USTEC: A new product from the Space Environment Centre Characterizing the Ionospheric Total Electron Content. GPS Solutions, Springer-Verlag, 9, 236–239.CrossRefGoogle Scholar
Schaer, S., Beutler, G. and Rothacher, M. (1998). Mapping and Predicting The Ionosphere. Proceedings of the IGS Analysis Centre Workshop, Darmstadt, Germany.Google Scholar
Schaer, S. and Steigenberger, S. (2006). Determination and Use of GPS Differential Code Bias Values. IGS Analysis Centre Workshop, Darmstadt, Germany.Google Scholar