Effects of External Ionosphere Anomaly Monitors on GNSS Augmentation Systems Studied with a Three-dimensional Ionospheric Delay Model - A Study for GBAS

S. Saito, N. Fujii

Abstract:	Spatial gradient of the ionospheric plasma density is one of the most important error source of differential GPS (DGPS) systems, such as a ground-based augmentation system (GBAS) or a space-based augmentation systems (SBAS). Various monitors have been implemented for those systems that require high level of integrity. Even with monitors, large safety margins are taken to ensure that possible miss-detection of ionospheric anomalies shall not result in a dangerous condition. This degrades availability of the systems and prevent them from more advanced operations. In this paper, the use of a VHF backscatter radar as a monitor of plasma bubbles for GBAS is proposed. A VHF backscatter radar can detect echoes from ionospheric irregularities associated with plasma bubbles. Since the scattering is intense, an inexpensive low-power (?10 kW peak) radar is sufficient. The effects are examined with simulation studies based on a three-dimensional ionosphere delay model in which the plasma bubble is taken into account. The results show that the backscatter radar can monitor plasma bubbles over wide area by a single station. It can detect plasma bubbles effectively, and possible errors in position of a GBAS user is significantly reduced. It is also shown that the backscatter radar is more effective when it is located closer to the magnetic equator. Further studies are needed to clarify the advantage and limitation of the backscatter radar as an external monitor for GNSS.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2611 - 2617
Cite this article:	Saito, S., Fujii, N., "Effects of External Ionosphere Anomaly Monitors on GNSS Augmentation Systems Studied with a Three-dimensional Ionospheric Delay Model - A Study for GBAS," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 2611-2617.
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