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It would be beneficial to ascertain whether RAIM and Advanced RAIM are useful for applications that take advantage of differential GNSS corrections for integrity

Receiver Autonomous Integrity Monitoring (RAIM) and Advanced RAIM (ARAIM) are very important techniques in aeronautical navigation, which are designed to improve the safety and reliability of navigation.RAIM ensures navigation accuracy by using multiple satellite signals to detect and troubleshoot erroneous measurements.ARAIM is an upgraded version of RAIM, which is not only capable of detecting and troubleshooting single satellite malfunctions, but also handles situations where multiple satellites are malfunctioning at the same time.

In civil aviation, RAIM is already widely used in area navigation and Required Navigation Performance (RNP) operations, while ARAIM is expected to enable instrument approach and vertical navigation in the next few years, which will reduce the reliance on augmentation system corrections and integrity information.

Mention of RAIM and ARAIM brings us to Septentrio, a company with a strong reputation in the GNSS field, specialising in the design and manufacture of high-precision GPS/GNSS receivers for demanding applications, with decimetre or centimetre-level accuracy even under difficult conditions.

Septentrio's Mosaic GNSS modules are at the forefront of its high-precision positioning technology offering, in particular the mosaic-X5, a compact tri-band receiver capable of utilising signals from all available GNSS constellations to achieve the highest degree of position availability even under challenging conditions.
The mosaic-X5 module incorporates Septentrio's unique AIM+ technology, an advanced on-board interference mitigation technique that suppresses interference ranging from simple continuous narrowband signals to complex broadband and pulsed jammers, ensuring optimal availability, reliability and accuracy.

A key advantage of ARAIM is the ability to directly represent and monitor faults on multiple satellites. It detects faults by comparing the full view position solution with the solution at the time of the hypothetical fault. If significant differences between solutions are found, ARAIM attempts to isolate the fault to a specific satellite, and if this cannot be done, it alerts the user that the operation is no longer safe.

However, ARAIM has a high computational complexity because it needs to monitor a large number of failure hypotheses. This is feasible for users with powerful processors, but may not be practical for most off-the-shelf automotive and maritime user equipment. Therefore, one possible solution is to combine similarly positioned satellites into a single hypothesis to reduce the number of hypotheses that must be checked, but this will reduce the resolution of individual satellite failures.

Overall, ARAIM is an important addition to integrity monitoring for augmented users, especially in situations where local failures due to multipath or RF interference are more likely than SIS failures mitigated by augmented systems. This needs to be taken into account when designing and procuring cost-effective user receiver and processor hardware, and Septentrio and its Mosaic GNSS modules, in particular the mosaic-X5, provide strong technical support and product assurance to achieve this goal.

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