Started 1996, on going
Summary
Static GPS baseline data are commonly processed using the least-squares method. To obtain reliable least-squares estimates, the most critical task is to correctly specify mathematical and stochastic models used in data processing. Mathematical modelling for GPS measurements is usually based on the so-called double differencing (DD) procedure, because it can cancel many systematic errors existing in GPS measurements, and the resultant DD measurements have a simplified mathematical model. In practice, however, stochastic modelling for GPS measurements is both a controversial topic and a difficult task to accomplish. In this research, the importance of the stochastic model in GPS precise positioning is emphasised. Some aspects of mis-specification in the stochastic model for GPS measurements are analysed. It is shown that the GPS measurements have a heteroscedastic, space- and time-correlated error structure, and that any mis-specification in the stochastic model may have a significant influence on ambiguity resolution and positioning results.
Results
A new method has been proposed, in which the aforementioned features of GPS errors are taken into account. Experimental results show that by using the estimated stochastic models, reliability of the ambiguity resolution and baseline component estimates can be improved and the resulting accuracy of the baseline components becomes more realistic.
References
Wang J (1999) Modelling and quality control for precise GPS and GLONASS satellite positioning. Ph.D thesis, School of Spatial Sciences, Curtin University, 171pp.
Wang J (1998) Stochastic assessment of the GPS measurements for precise positioning. Proceedings of the 11th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GPS-98, Nashville, TN, September 15-18, pp. 81-89.
Wang J, Stewart M and Tsakiri M (1998) Stochastic Modelling for GPS Static Baseline Data Processing, Journal of Surveying Engineering, Vol. 124, No. 4, pp. 171-181.
Wang J and Stewart M (1996) Stochastic assessment of the double differenced GPS observations. Paper presented at Annual Research Seminar, School of Geomatic Engineering, The University of New South Wales, Sydney, NSW, November.
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