Assessment of Alternative Techniques to Mitigate Ionosphere Gradients for Local Differential Systems

Jed Dennis

Abstract:	This paper identifies and assesses two potential alternate methods to mitigate differences in ionosphere delay between the signal observed by a user and the ground station in local differential systems. Ionosphere gradients between the user and the ground station introduce a differential delay. When the ionosphere gradient is large, the impact on the differentially corrected position can be quite large. Current mitigation methods identify ionosphere gradients and remove satellites without any specific consideration if the geometry makes the gradient hazardous. This paper assesses the potential to limit the size of the gradient threat model based on satellite-ground station-user geometry as measured by ionosphere pierce point distance and develops another method that operates on the ionosphere delay difference indicated by the codeminus-carrier measurement in place of ionosphere gradient detection.
Published in:	Proceedings of the 29th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2016) September 12 - 16, 2016 Oregon Convention Center Portland, Oregon
Pages:	1368 - 1375
Cite this article:	Dennis, Jed, "Assessment of Alternative Techniques to Mitigate Ionosphere Gradients for Local Differential Systems," Proceedings of the 29th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2016), Portland, Oregon, September 2016, pp. 1368-1375. https://doi.org/10.33012/2016.14675
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