Ionospheric Threat Parameterization for Local Area Global-Positioning-System-Based Aircraft Landing Systems

摘要

Observations of extreme spatial rates of change of ionospheric electron content and the characterization strategynfor mitigation applied by the U.S. local area augmentation system are shown. During extreme ionospheric activity,nthe gradient suffered by a global navigation satellite system user a few kilometers away from a ground referencenstation may reach as high as 425 mm of delay (at the GPS L1 frequency) per km of user separation. The method ofndata analysis that produced these results is described, and a threat space that parameterizes these possible threats tonuser integrity is defined. Certain configurations of user, reference station, global navigation satellite systemsatellite,nand ionospheric storm-enhanced densitymay inhibit detection of the anomalous ionosphere by the reference station.