LDGPS Performance Assessment Using the JPALS Availability Model

J.R.A. Stevens, C. Varner, S.M. Boettcher, J.M. Glaeser, J.E. Weir

Abstract:	Development of the Land Based variant of the Joint Precision Approach and Landing System (JPALS) is able to leverage work already performed for the Local Area Augmentation System (LAAS) which has similar requirements for accuracy, integrity and continuity. However, JPALS will require the use of different receivers and antennas and may also employ dual frequency processing techniques which are not currently available to LAAS. To permit the evaluation of alternative candidate technologies and architectures for the JPALS Local Area Differential GPS (LDGPS), an availability simulation model has been employed. This tool, which is based upon similar concepts originally developed for LAAS, has been used to explore the performance impact of different range domain error models, in particular those for ground and airframe multipath and for the residual ionosphere error. This paper describes the background to the development of the range domain sigma models which have been employed in the LDGPS availability simulations. Studies have included the evaluation of different smoothing techniques using recorded data from JPALS flight tests, and the assessment of the multipath mitigation performance of different technologies in both the ground and airborne environments. Details of the integrity and continuity parameters which impact the availability modeling are also included. Availability simulation results are presented which illustrate the long term service availability predicted to be achievable over different proportions of the Earth’s surface. The results demonstrate that the current JPALS requirements for Category I approaches are readily achievable, and alternative architectures are evaluated against the Category II requirements.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	1786 - 1797
Cite this article:	Stevens, J.R.A., Varner, C., Boettcher, S.M., Glaeser, J.M., Weir, J.E., "LDGPS Performance Assessment Using the JPALS Availability Model," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 1786-1797.
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