Earth-Surface Multipath Detection and Error Modeling for Aircraft GPS Receivers

Zhen Zhu and Frank van Graas

Peer Reviewed

Abstract: For aircraft precision approach operations, Earth-surface multipath observed by an aircraft GPS antenna degrades the accuracy of pseudorange measurement. Of particular concern are stabilized approaches over water where the water reflection of the GPS signal could generate sustained multipath error. A novel multipath detection method is introduced in this work. It provides accurate estimates of multipath strength and fading frequency using a software-defined radio GPS receiver and radio frequency data collected from a top-mounted antenna. Combined with analysis of flight-test data collected from both the top-mounted antenna and a bottom-mounted antenna, the new method allows for a realistic model of the Earth-surface multipath environment. Narrow-band and wide-band airborne receivers are simulated, and their responses to Earth-surface multipath are evaluated. The two receivers are found to have different code phase error signatures in the same multipath environment. Under different conditions, both receivers can experience smoothed pseudorange bias of up to 0.3 m.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 56, Number 1
Pages: 45 - 56
Cite this article: Zhu, Zhen, van Graas, Frank, "Earth-Surface Multipath Detection and Error Modeling for Aircraft GPS Receivers", NAVIGATION, Journal of The Institute of Navigation, Vol. 56, No. 1, Spring 2009, pp. 45-56.
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