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Session B1a: GNSS Integrity and Augmentation

Dual-Frequency Multi-Constellation GBAS Multipath-Antenna Group Delay Model Evaluation
Yuan Liu, Kun Fang, Beihang University; Kelin Zhong, Commercial Aircraft Corporation of China Ltd.; Zhipeng Wang, Beihang University; Yanbo Zhu, Aviation Data Communication Corporation
Location: Beacon A

Peer Reviewed

Ground Based Augmentation System (GBAS) uses ground reference receivers with known positions to provide differential information to aircraft users based on the correlation between airborne error and ground error, thereby reducing the error through differential processing and improving performance. The dual-frequency multi-constellation (DFMC) GBAS can use dual frequency signals from multiple constellations, which can further improve service performance and meet the minimum performance requirements of CAT-IIIb. As a system closely related to life safety, the integrity of GBAS is one of its key performance indicators. The GBAS ensures its integrity through integrity monitoring both on the ground and onboard. Antenna Group Delay Variation (AGDV) is an error source for airborne users. It is currently bounded together with multipath as part of the airborne error. Separating the AGDV from the multipath improves the accuracy of integrity monitoring. Based on the Code Minus Carrier (CMC) algorithm, the multipath-AGDV combined error is extracted, the trend term and residual term are extracted based on the elevation distribution in the data, and the impact of AGDV deviation on the current dual-frequency AGDV model is evaluated in this paper. The protection level is further calculated based the deviation. The results show that the protection level of the B1C signal increased by 0.3385 meters on average, while the protection level of the B2a signal increased by 0.6061 meters on average.



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