Flight Test of the JPALS LDGPS Demonstration System

Christopher J. Bett, Stuart A. Simon, Bruce J. Farnworth, Robert W. Boyd and James J. Brewer

Abstract:	The Joint Precision Approach and Landing System (JPALS) Local Area Differential Global Positioning System (LDGPS) Program for the Architecture Requirements Definition (ARD) involves the examination of available technologies to support the development of requirements for guidance quality, GPS receiver vulnerability and interoperability with civil differential GPS systems. Program efforts include test and evaluation of demonstration hardware to record raw sensor and environmental data during precision approaches in high levels of electromagnetic interference (EMI). Raytheon Company has developed the JPALS LDGPS Demonstration System, a test platform hosting multiple antenna, antenna electronics (AE) and GPS receiver technologies integrated to provide a differential GPS precision approach capability. The demonstration system is based primarily on the civil Local Area Augmentation System (LAAS) and consists of a ground segment and an airborne segment. The ground segment forms carriersmoothed pseudorange corrections and broadcasts LAAS Type 1, 2 and 4 Messages in accordance with RTCA DO- 246A. The airborne segment forms a carrier-smoothed corrected pseudorange solution and indicates course deviations to the pilot. The Demonstration System is configured to collect data from all integrated sensor electronics, the differential correction processor, and the navigation processor. The Demonstration System was implemented to perform approximately 60 hours of precision approaches (over 280 approaches) at Holloman AFB, NM using the USAF 46th Test Group C-12J test aircraft. Collected data is used to develop and refine simulations, models and analyses for the purposes of assessing guidance quality in the presence of high levels of EMI. Substantiated critical performance parameters will be useful for the JPALS System Program Office to shape the JPALS LDGPS Engineering and Manufacturing Development program and/or will identify the technology roadmap to meet the JPALS LDGPS objectives. This paper describes the JPALS LDGPS Demonstration System design and capabilities, ARD flight test activities and preliminary results. The significance of the results presented is traced directly to the diversity of approach data collected simultaneously by multiple GPS sensor technologies in high EMI environments. To our knowledge, this has not been previously accomplished.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	1159 - 1169
Cite this article:	Bett, Christopher J., Simon, Stuart A., Farnworth, Bruce J., Boyd, Robert W., Brewer, James J., "Flight Test of the JPALS LDGPS Demonstration System," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 1159-1169.
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