Title: Horizon-to-elevation Mask: A Potential Benefit to Ionospheric Gradient Monitoring
Author(s): Safoora Zaminpardaz
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: 1764 - 1779
Cite this article: Zaminpardaz, Safoora, "Horizon-to-elevation Mask: A Potential Benefit to Ionospheric Gradient Monitoring," Proceedings of the 29th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2016), Portland, Oregon, September 2016, pp. 1764-1779.
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Abstract: Monitoring and detecting significant ionospheric spatial gradients are of importance for safety-critical aviation applications. During the period a satellite is above the elevation mask, Ground Based Augmentation System (GBAS) monitors must be capable of instantaneously detecting hazardous ionospheric gradients that affect the signals of that satellite. At the time the satellite rises above the elevation mask, the GBAS monitors ability to detect hazardous ionospheric spatial gradients depends on the data of only that epoch since no observations were recorded beforehand. The detection ability of the monitors would, however, be improved if the receivers could collect the data during the period when the satellite elevation is increasing from horizon to elevation mask. In this paper, we explore the potential benefits of using such data in terms of ionospheric spatial gradient detectability. We show how and under which circumstances this data can be employed to successfully detect a significant ionospheric gradient. Supported by simulation results, our analytical investigations demonstrate that reliable detection gets realized upon applying integer ambiguity resolution (IAR). The IAR success rate, based on the single-frequency GPS data, can attain high values of 1 ? 10?6 before the satellite elevation reaches the value of 5? , if at least 8 antennas are utilized. This number of antennas can be reduced to even less than 4 in case the IAR is carried out on the basis of dual-frequency data. Resolving the double-difference (DD) ambiguities, the Minimal Detectable Biases (MDBs) for the ionospheric spatial gradient experience a dramatic decrease so that they can reach the required values before the elevation of the satellite reaches 5? , even when the baselines between antennas are shorter than 500 meters.