Use of Inertial Integration to Enhance Availability for Shipboard Relative GPS (SRGPS)

C.R. Offer, P.D. Groves, A.A. Macaulay, D.L.J. Nash, C.J. Mather

Abstract:	QinetiQ has recently undertaken research into the technology readiness and feasibility of generic Global Positioning System (GPS) based shipboard recovery architectures and concepts. Alongside this work, QinetiQ has also undertaken investigation and demonstration of the Concept of Operations (CONOPS) for GPS based automatic shipboard approach and vertical landing for the STOVL JSF (F-35B) aircraft, which culminated in a world-first shipboard automatic landing of a Short Take-Off and Vertical Landing (STOVL) aircraft in May 005. These combined activities have enabled evaluation of Shipboard Relative GPS (SRGPS) navigation architectures and concepts, as relevant to programmes such as Joint Precision Approach and Landing System (JPALS), in a representative environment, including solution generation and integrity monitoring techniques. Whilst Inertial Navigation System (INS) measurements have been assumed to form part of any SRGPS solution architecture, the level and complexity of integration on both the ship and aircraft remains subject to trade. This paper reports on the implications of integrating INS measurements into generic GPS based shipboard recovery architectures, in increasing levels of integration complexity. The addition of INS data into the SRGPS architecture for enhancement of integrity monitoring functions is discussed. Integrity monitors for key failures, such as carrier phase cycle slip detection and repair, can be enhanced utilising an integrated approach. Incorporation of INS data into the carrier phase relative navigation scheme is also discussed, offering the capability to improve robustness in marginal conditions and in the presence of failures such as cycle slips or single frequency degraded operation. An enhancement in continuity can also be realised, in that the integrated solution can be made more robust to constellation changes and outages, with a resultant impact on critical satellite and time-toalarm assumptions. Finally, the integration of INS into the GPS receiver in order to realise enhanced anti-jam protection is described. Performance in the interferencerich shipboard operational environment and under conditions of deliberate jamming can be improved. There is additionally the opportunity to reduce measurement noise through aiding and adaptation of receiver tracking loops, thus enhancing accuracy and integrity under clear air and jamming conditions.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	726 - 737
Cite this article:	Offer, C.R., Groves, P.D., Macaulay, A.A., Nash, D.L.J., Mather, C.J., "Use of Inertial Integration to Enhance Availability for Shipboard Relative GPS (SRGPS)," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 726-737.
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