Summary of Accuracy Improvements from the GPS Legacy Accuracy Improvement Initiative (L-AII)

Tom Creel, Arthur J. Dorsey, Philip J. Mendicki, Jon Little, Richard G. Mach, and Brent A. Renfro

Abstract:	The completion of the GPS Legacy Accuracy Improvement Initiative (L-AII) project has more than doubled the amount of data available to the GPS Master Control Station (MCS) by adding data from the National Geospatial-Intelligence Agency (NGA) network of GPS monitoring stations. The NGA-led improvements for the MCS are three-fold: improved accuracy of the MCS Kalman filter, improved accuracy of the broadcast ephemeris, and improved ability to monitor the performance of the GPS space vehicles. The benefits of these improvements apply to all users, both military and civilian. Preliminary results from L-AII through November 2005 were presented at the Institute of Navigation (ION) National Technical Meeting (NTM) in January 2006. Since November 2005, the remaining improvements to the MCS Kalman filter and solar radiation pressure models have been completed and the number of NGA stations providing data has increased. This paper presents further analysis of the L-AII results that illustrate the long-term sustained GPS performance improvements available for all users. The analysis includes performance measures of the MCS Kalman filter, the signal-in-space user range errors, and the impact of LAII on positioning accuracy.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	2481 - 2498
Cite this article:	Creel, Tom, Dorsey, Arthur J., Mendicki, Philip J., Little, Jon, Mach, Richard G., Renfro, Brent A., "Summary of Accuracy Improvements from the GPS Legacy Accuracy Improvement Initiative (L-AII)," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 2481-2498.
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