A Simple and Effective Approach to Real-Time Ionospheric Monitoring at Low Latitudes and Its Applicability to GBAS

Abstract

This paper proposes a strategy for improving ionospheric detection of threatening conditions, motivated by issues with ground-based augmentation systems (GBASs) at low latitudes. A methodology is developed for a real-time alerting system that monitors the ionosphere state using surrounding ground stations and sends alerts to differential global navigation satellite systems services when threatening conditions are detected. The method is based on time-step gradients and data gap analysis to detect ionospheric disturbances and to declare periods for affected satellite signals to be unavailable. Validation was performed with real data using the largest observed gradients from the Brazilian ionospheric threat model. The results demonstrate that the method is effective, detecting the vast majority of previously known threatening gradients. An availability assessment was also performed to assess for a loss of availability resulting from the implementation of this technique. Applications of the developed technique include the improvement of low-latitude nighttime GBAS availability.