Bounding Errors Caused by Nominal GNSS Signal Deformations

Gabriel Wong, R. Eric Phelts, Todd Walter, Per Enge

Abstract:	Nominal signal deformations are present in GNSS-GPS and WAAS-GEO satellite signals. They result in pseudorange errors, which in turn cause navigation errors for GNSS users. These navigation errors depend on the user- and reference-receiver configuration parameters as well as satellite geometry and user location. Previous papers by the authors focused on obtaining a better understanding of the pseudorange errors caused by nominal signal deformations. For this paper, we examine the user navigation error effects of nominal signal deformations from many perspectives: based on the pseudorange tracking errors from real GPS data, what would be the resultant worst case position errors? When do they become a significant integrity concern? Which user receiver configurations appear least (or most) sensitive to them? What are the effects in the dual-frequency and/ or depleted constellation configurations? The user errors are also a function of best-case and worst-case satellite geometries at the user receiver, which are in turn dependent on user/ reference receiver locations. Nominal and degraded satellite geometries for different user locations were generated using the MATLAB Algorithm Availability Simulation Tool (MAAST) Matlab toolbox, developed at Stanford, and the best and worst case position errors were determined for these cases.The results presented are for typical WAAS aviation users of a single-frequency, GPS-only constellation, but they can be easily extended to multiple-frequency, multi-constellation systems. These results may be especially important with the upcoming increasing availability of dual-frequency systems – the use of linear combinations of signals from the same satellite to remove ionospheric errors in turn scales the signal-deformation-induced errors.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2657 - 2664
Cite this article:	Wong, Gabriel, Phelts, R. Eric, Walter, Todd, Enge, Per, "Bounding Errors Caused by Nominal GNSS Signal Deformations," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 2657-2664.
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