The Influence of Atmosphere on GNSS Signals for High Altitude Orbit and Lunar Mission

Guoliang Sun and Rui Fan

Peer Reviewed

Abstract:	High altitude orbit and lunar users can only receive GNSS signals from the other side of the earth due to the signals’ earth-oriented characteristic. A portion of GNSS signals, which spread through the atmosphere, will be distorted because of the atmosphere refraction, resulting in its slight and continuous change of direction. The usage of such GNSS signals for ranging and positioning will cause location errors which shouldn’t be neglected. For this reason, the influenced GNSS signals were shielded in the past study when GNSS signals were applied to high altitude orbit and lunar localization. The availability and accuracy will get worse if we abandon the GNSS signals spreading through the atmosphere since the number of visible satellites was already small under the condition of high altitude orbit or lunar localization. In view of the problems above, we first build a model of ionosphere and troposphere refraction in order to simulate the trace of the GNSS signals which spread through the atmosphere. It shows that the distortion resulting from the ionosphere is almost negligible and the signal bending in troposphere is much larger than it is in ionosphere. The largest bending angle of the signals will reach its maximum of approximately 1.5 degrees when the signal passing through tangent to the ground. Furthermore, we analyze the number of visible satellites, the availability of the whole system and the DOP(dilution of precision) under the condition of both considering and not considering atmosphere’s influence, directing at both high altitude orbit and lunar localization. It shows that the use of signals going through the atmosphere can improve the availability of GNSS system both for high altitude orbit and for lunar orbit. The GNSS availability is improved when we set a DOP threshold with application to lunar orbit.
Published in:	Proceedings of the 2017 International Technical Meeting of The Institute of Navigation January 30 - 2, 2017 Hyatt Regency Monterey Monterey, California
Pages:	162 - 169
Cite this article:	Sun, Guoliang, Fan, Rui, "The Influence of Atmosphere on GNSS Signals for High Altitude Orbit and Lunar Mission," Proceedings of the 2017 International Technical Meeting of The Institute of Navigation, Monterey, California, January 2017, pp. 162-169. https://doi.org/10.33012/2017.14907
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