Impacts of Ionospheric Scintillation on Ground CCD Monitor Performance for GAST D Operations in the Equatorial Region

Kiyoung Sun, Hyeyeon Chang, Jiyun Lee*

Ground-Based Augmentation System (GBAS) Approach Service Type D (GAST D) requires additional monitoring for ionospheric disturbances to meet its high level of integrity to support Category (CAT) II/II precision approach and landing operations. Ionospheric scintillation is one of significant concerns for GAST D operations in the equatorial region, since the scintillation effects not only induce signal loss, but increase noise components of test statistics of GAST D integrity monitors. The response of test statistics under various scintillation conditions thus must be analyzed to meet performance requirements of the integrity monitors. This study analyzed the behavior of ground code-carrier divergence (CCD) monitor test statistics for various scintillation conditions by using datasets obtained from reference stations in Brazil. We derived relationships between the standard deviation of test statistics and parameters representing scintillation conditions (e.g. C/N0, σφ, S4). The results of this study can be used to evaluate the GAST D performance under scintillation.

Keywords: GBAS, GAST D, ionospheric scintillation, CCD monitor