Signal deformation fault monitors for dual‐frequency GBAS

This paper proposes a new dual‐frequency signal deformation fault monitor, which can effectively reduce the time delay at the Ground‐Based Augmentation System (GBAS) airborne user from the airborne filter initialization to the time when it incorporates ground corrections and user measurements for navigation, assuring the system integrity at the same time. The new monitor is applied together with the existing Honeywell signal deformation monitor and Code‐Carrier Divergence monitors to protect the airborne users against the signal deformation faults. In addition, the probability of missed detection of the monitors is assessed for the GBAS Approach Service Types (GAST) F, which supports the Category (CAT) II and III precision approaches based on the multifrequency and multiconstellation. As a result, the proposed monitor together with the Honeywell and the CCD monitors is able to assure the system integrity for all fault cases within the threat space. The result also shows that the addition of the proposed monitor can reduce the time delay by 80%; moreover, it can even reduce the recommended time delay below 50 s. Consequently, it can avoid the unnecessary delays for the use of newly available satellites at the airborne.