The Potential Use of GPS Signals as Ocean Altimetry Observables

Sien-Chong Wu, Thomas Meehan and Larry Young

Abstract:	This paper investigates a potential application of GPS signals for ocean altimetry. The altimetry information is derived from dual-frequency GPS signals reflected from the ocean surface and received at a low-altitude satellite. Such altimetry would be superior to conventional radar altimetry in three respects: (1) Thanks to the global GPS constellation, sea surface heights at up to 12 points can be determined instead of a single nadir point at any one time; (2) The user satellite only need be equipped with a GPS receiver which also serves as the receiver acquiring direct GPS signals for orbit determination; and (3) The delay spread of the reflected signal is a function of the sea- surface roughness, so that this technique may allow scatterometry-like measurements of surface weather conditions. The paper addresses several criteria for the GPS altimetry to be viable. These include the signal strength, delay characteristics and polarization of the reflected GPS signals, the receiver capability of discriminating and tracking these signals from the direct signals, the determination of the reflection points on the sea surface, and the information content of these signals.
Published in:	Proceedings of the 1997 National Technical Meeting of The Institute of Navigation January 14 - 16, 1997 Loews Santa Monica Hotel Santa Monica, CA
Pages:	543 - 550
Cite this article:	Wu, Sien-Chong, Meehan, Thomas, Young, Larry, "The Potential Use of GPS Signals as Ocean Altimetry Observables," Proceedings of the 1997 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1997, pp. 543-550.
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