Positioning Impacts from Imbalanced Atmospheric GPS Network Errors

Yong Won Ahn, Don Kim and Peter Dare

Abstract:	For dual-frequency GPS observables, one of the largest error sources affecting high-precision positioning solutions arises from the unmodelled troposphere. In normal tropospheric cases, it is difficult to evaluate its positioning impacts as the estimated parameters may be obscured by other error sources. In this paper, we have extensively analyzed GPS network data from one of the most inhomogeneous atmospheric cases. We have examined the positioning impacts due to additional tropspheric gradient parameter estimation. In total, a data set from 18 GPS stations for 9 days from the Korea peninsula has been collected and processed during the passage of typhoon RUSA in 2002. Based on the estimated tropospheric delays from the GPS observables, the precipitable water vapor (PW) has been calculated in order for it to be evaluated and compared with those from independent observables (radiosonde and real precipitation records). GPS-derived PW values (with the inclusion of the gradients) demonstrate that they are correlated with the time series of radiosondes and actual precipitation. In this imbalanced network case, we investigated the possible positioning improvement including the gradient parameters in the processing. Unlike when under normal tropospheric conditions, the additional gradient parameter estimation can greatly reduce the instability of a coordinate solution. In addition, we observed that this could be more important for a station which experienced more inhomogeneity from the troposphere.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	2302 - 2312
Cite this article:	Ahn, Yong Won, Kim, Don, Dare, Peter, "Positioning Impacts from Imbalanced Atmospheric GPS Network Errors," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 2302-2312.
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