Analysis and Evaluation of Various Ionospheric Models for Potential Use in the NDGPS Service

D. Dodd, S.B. Bisnath, A. Cleveland, and M. Parsons

Abstract:	The U.S. Coast Guard in cooperation with other federal agencies, including the Department of Transportation and the Federal Railroads Administration has begun the modernization of its highly successful Nationwide Differential Global Positioning System (NDGPS) beacon network. Aside from simply replacing aging equipment, the modernization program calls for investigations into improving the quality of the service in terms of integrity, availability, precision and accuracy. One aspect being studied is improved handling of atmospheric refraction of the incoming GPS signals. The National Geodetic Survey (NGS), Space Environment Center (SEC) and Forecast Systems Laboratory (FSL) at the National Oceanic and Atmospheric Administration (NOAA), Federal Aviation Administration (FAA) and the Jet Propulsion Laboratory (JPL) have developed ionospheric and tropospheric delay products for test areas within the continental U.S. The Hydrographic Science Research Center in the Department of Marine Science at the University of Southern Mississippi in cooperation with the Coast Guard is analyzing these data products in support of the following overall goals: to characterize the quality of the NOAA atmospheric correctors; to estimate the effects on positioning by applying the correctors to GPS data processing; and to provide options for ingesting these correctors in the NDGPS modernization program. This paper presents the results of a study conducted to evaluate several different ionosphere error mitigation models and methods. It describes how satellite coverage, as a function of ionosphere corrector availability, plays a significant role in position accuracy.
Published in:	Proceedings of the 2006 National Technical Meeting of The Institute of Navigation January 18 - 20, 2006 Hyatt Regency Hotel Monterey, CA
Pages:	195 - 205
Cite this article:	Dodd, D., Bisnath, S.B., Cleveland, A., Parsons, M., "Analysis and Evaluation of Various Ionospheric Models for Potential Use in the NDGPS Service," Proceedings of the 2006 National Technical Meeting of The Institute of Navigation, Monterey, CA, January 2006, pp. 195-205.
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