Absolute Slant Ionosphere Gradient Monitor for GAST-D: Issues and Opportunities

Kurzfassung

Strong ionospheric gradients above 300 mm/km remain a threat for single frequency GBAS users including those conducting CAT II and CAT III precision approaches under GAST-D protocols. This can be overcome using a network of single-frequency, double- differenced carrier-phase-based monitors as proposed in [1]. The detection performance of this monitor is very sensitive to the level of carrier phase residual error. Therefore, an architecture using 4 aligned receivers with optimal separation that allows the highest carrier phase residual error (8.65mm, one standard deviation) has been proposed in [2]. This level of carrier phase residual error provides 100% detectability of absolute slant ionosphere gradients in the range [-2000, -300] and [300, 2000] mm/km for a probability of missed detection and false alarm lower than 10