A Simple and Effective Approach to Real-Time Ionospheric Monitoring for GBAS in Low Latitudes

Leonardo Marini-Pereira, Alison de Oliveira Moraes, Sam Pullen

Peer Reviewed

Abstract:	This paper proposes a strategy to improve the performance of Ground-Based Augmentation Systems (GBAS) in low latitudes. A methodology was developed for an alerting system that uses surrounding ground stations to monitor the ionosphere state in real time and send alerts to a GBAS facility when threatening conditions are detected. The method is based on time-step gradients used as a test statistic along with data gap analysis to detect ionospheric disturbances and declare periods for affected satellite signals to be declared unavailable. The method for translating detections of threatening conditions into alerts to not use specific satellites depends on three different parameters, and 30 different combinations of these were tested. Validation was performed with real data using the largest observed gradients that form the Brazilian ionospheric threat model. The results demonstrated that the method is highly effective, detecting the vast majority of previously known threatening gradients within a maximum temporal tolerance of 5 minutes. An availability assessment was also performed to check for availability outages resulting from the application of the technique. These outage periods varied significantly with day of year and location. Cases were found in which all threatening gradients were detected without loss of availability. However, in the worst case, the application of the alerting method with the most sensitive set of parameters resulted in an outage period of approximately 5 hours using monitoring stations in the region of the city of Salvador, Brazil. Despite such loss of availability in the worst-case outage, this result is far better than declaring the system totally unavailable every night (when equatorial plasma bubbles typically occur). The application of the developed technique has the potential to improve low-latitude nighttime GBAS availability.
Published in:	Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022) September 19 - 23, 2022 Hyatt Regency Denver Denver, Colorado
Pages:	2954 - 2969
Cite this article:	Marini-Pereira, Leonardo, Moraes, Alison de Oliveira, Pullen, Sam, "A Simple and Effective Approach to Real-Time Ionospheric Monitoring for GBAS in Low Latitudes," Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022), Denver, Colorado, September 2022, pp. 2954-2969. https://doi.org/10.33012/2022.18339
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