Assessment of multibaseline collaborative ionospheric gradient monitor based on BDS

Hazardous ionospheric gradient is a critical risk source to be monitored for navigation service supported by the ground-based augmentation system (GBAS). Carrier phase-based ionospheric gradient monitor can simultaneously be sensitive to multiple types of hazardous ionospheric gradients. The monitor is developed by using multiple spatially separated reference receiver antennas. The performance of traditional ionospheric gradient monitor is greatly depending on the baseline length and direction consists of antenna pairs. The null space ionospheric gradient monitor is widely adopted to reduce the dependence of ionospheric gradient monitoring on baseline selections. With the BeiDou system (BDS) widely providing navigation services in the civil aviation, the long-term ionospheric gradient monitoring facility based on BDS is under continuous construction. In this paper, we will focus on evaluating the sensitivity of multi-baseline collaborative ionospheric gradient monitoring based on BDS. A two-dimensional numerical simulation is utilized to verify the multi-baseline collaborative ionospheric gradient monitoring method. The simulation results have shown that the null space ionospheric gradient monitor has the smallest detection blind zones compared with the other traditional method. In addition, it has been proven that the real-time protection of hazardous ionospheric gradient by the multi-baseline collaborative ionospheric gradient monitoring method based on BDS is achievable.