Detecting ionospheric threat for GBAS based on spatial-temporal method

Ionosphere anomalies affect navigation signal propagation in space with varying degrees, leading to a non-stationary, unpredictable and even immeasurable ionosphere delay, and finally degrading the performance of LAAS, becoming the most hazardous factor in precision approaching and landing. To monitor ionosphere anomalies and assess its impact on navigation integrity is a difficult point in the related research field. In this paper, a novel dual-frequency ionosphere anomalies detection framework is proposed, with combination of ionosphere rate and delay anomalies detection, dual-frequency measurements are considered to eliminate hardware delay uncertainty. In the rate detection fold, state model is modified to adjust ionosphere temporal variation; in the delay detection fold, cascaded filters are constructed to achieve better de-noising performance. An equal gradient plane model is put up to evaluate the availability under different anomalies condition, and experiments show that the proposed new detection framework has advantages in the aspect of accuracy, detection sensitivity and availability.