Advanced Receiver Autonomous Integrity Monitoring for Aircraft Guidance using GNSS
Eissfeller, Bernd, Univ.-Prof. Dr.-Ing.
Eissfeller, Bernd, Univ.-Prof. Dr.-Ing. ; Enge, Per Univ.-Prof. Dr.-Ing.
Tag der Abgabe der Arbeit:
Tag der mündlichen Prüfung:
ARAIM, RAIM, Integrity, GNSS, Position Solution, Least Squares Estimator, Accuracy, GNSS Augumentation System
The core satellite constellations were not developed by system providers to satisfy the strict requirements of Instrument Flight Rules (IFR) navigation. For that reason, the GNSS capable equipment used for IFR operations augments the GNSS signal-in-space (SIS) to ensure integrity and accuracy. Integrity is required to guarantee that an airplane will not deviate from its intended course beyond the Alert Limit (AL) without a warning to the pilot. Unknown course deviations could result in a significant navigation error or even a collision. The simplest form of globally available augmentation system is the Receiver Autonomous Integrity Monitoring (RAIM) which currently augments only the GPS L1 signal. Based on DO-208  the FAA has published a Technical Standard Order (TSO-C129c) that does not specify which RAIM algorithm is to be used. It specifies that the RAIM function shall provide worldwide availability of at least 95%. Today’s GPS (L1)-RAIM is approved for non-precision approaches and provides only lateral guidance for Oceanic, En route, Terminal, LNAV approaches and Departure RNP/RNAV operations. Continued improvement, transparency, and robustness of GPS service on the L1 frequency are the key elements of the current RAIM’s performance achievements. By having multiple GNSS constellations, where the number of satellites added into the navigation solution increases, RAIM lateral navigation performance is expected to be better. Precision approaches with vertical guidance have even more stringent requirements on accuracy and integrity of GNSS navigation performance. Here, the threat of misleading information moves from major to the hazardous category. In practice, this means that the integrity monitoring chain must go through much more scrutiny and it is not enough to have single frequency (L1) navigation. Dual frequency navigation performance becomes the essential condition for GNSS-based operations where the priority is vertical guidance. GPS (L1)-RAIM conceptual design is undergoing a revolution as many GNSS are on the way to reaching their full operational capability, offering more modernized signals on multiple frequencies. The new algorithms and assumptions that could provide vertical guidance have been labeled 'Advanced RAIM.' EUROCAE currently has plans to publish MOPS for GPS/Galileo applications that will require an ARAIM service, initially to support horizontal navigation only and current generation surveillance requirements.
The purpose of this dissertation is to show the capability and benefits of the ARAIM system and its possible smooth integration into the standards (MOPS/EUROCAE). The work is scoped to show the flexibility and availability of ARAIM to provide lateral and vertical guidance for any air vehicle during all phases of flight, up to and including final approach guidance to a decision height of 200 feet (61 m). It will elaborate in greater detail on all performance requirements, which are as important as the accuracy of the navigation solution. The top four goals of the dissertation are to: describe integrity monitoring algorithms in the multi-GNSS environment; show differences and benefits of the ARAIM concept over traditional RAIM; answer a question on how many satellites we need to have a robust service; analyze expected service performance as a function of design trade-offs.
With a comprehensive description of the ongoing development of ARAIM user algorithms with a lot of material for the reproduction of the current results, there is enough information for receiver designers. For the constellation service providers, it could be interesting to reveal the parameters that mostly contribute to the overall system performance in the near term. Here, the focus is to provide an overview and transparency of the real tradeoffs and requirements for aviation users. This dissertation can also serve as a starting point for a design of similar concepts that could also be adopted for applications other than aviation (e.g., maritime navigation, railway applications).
The core satellite constellations were not developed by system providers to satisfy the strict requirements of Instrument Flight Rules (IFR) navigation. For that reason, the GNSS capable equipment used for IFR operations augments the GNSS signal-in-space (SIS) to ensure integrity and accuracy. Integrity is required to guarantee that an airplane will not deviate from its intended course beyond the Alert Limit (AL) without a warning to the pilot. Unknown course deviations could result in a signifi... »
Fakultät für Luft- und Raumfahrttechnik
LRT 9 - Institut für Raumfahrttechnik und Weltraumnutzung