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Advanced Receiver Autonomous Integrity Monitoring (ARAIM) is an enhancement to the traditional Global Positioning System (GPS) single frequency RAIM - an airborne receiver functionality that performs fault detection and exclusion on GPS satellites. The proliferation of Dual-Frequency, Multi-Constellation, (DFMC) Global Navigation Satellite System (GNSS) signals is an enabler for the conception, development, acceleration, standardisation and certification of the ARAIM technology within the aviation domain in order to achieve worldwide Localizer Performance with Vertical guidance to decision height of 200 feet (LPV-200) with vertical alert limit of 35 metres. The latter is a capability to support GNSS-based aircraft operations for all phases of flight. This paper presents the design, development and flight experimentation activities conducted within the framework of the project known as Global ARAIM for Dual-Constellation (GLAD). GLAD adopts and implements, as a prototype, the baseline ARAIM algorithm proposed by the Working Group C (WG-C) ARAIM Technical Subgroup (TSG) in a commercial grade Multi-Mode Receiver (MMR). Within the scope of the development, the impact of computational loading for the GNSS receiver is discussed, particularly related to the processing of the algorithm in order to manage the variation of probability information of GNSS satellites and constellation failures. The Integrity Support Message (ISM) forms the core of the ARAIM concept. It provides flexibility in varying satellite and/or constellation parameters to be used within the ARAIM algorithm at varying update rates. The generation of an ISM along with the means to do so are elaborated. To conclude this paper, the verification and flight experimentation plans and trials to validate Horizontal ARAIM (H-ARAIM) and Vertical ARAIM (V-ARAIM) offline are presented along with the results to assess the performance of ARAIM in support of Required Navigation Performance (RNP) 0.3 and LPV-200 requirements. |
