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Wide Area Differential GPS Field Study

Published online by Cambridge University Press:  21 October 2009

Ivan Catchpole ,
Peter Upton ,
Andrew Sinclair  and
Jim Nagle
Ivan Catchpole
Affiliation:
(Signal Computing Ltd.)
Peter Upton
Affiliation:
(Signal Computing Ltd.)
Andrew Sinclair
Affiliation:
(Royal Greenwich Observatory)
Jim Nagle
Affiliation:
(Inmarsat, UK)
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Abstract

Inmarsat commissioned the field study to be carried out by Signal Computing Ltd. in association with the Royal Greenwich Observatory. The study aimed to identify the commercial suitability of Wide Area Differential GPS (WADGPS) corrections. The corrections provided to users will be relayed via Inmarsat-3 geostationary satellites and are required to be valid over the footprint of an entire Inmarsat ocean region (approximately one third of the Earth's surface).

The study has been conducted within the Inmarsat Atlantic Ocean Region East. Trials took place over a five-month period to achieve a representative set of data. Six widely-distributed collection sites were used to ensure that the maximum duration of satellite data were received and that a representative model for atmospheric effects was obtained. Analysis is restricted to the use of GPS carrier and phase data obtained using the C/A code transmitted by Block II satellites only.

This paper presents the analysis of data collected during a four-day trial period. The ability to determine the GPS satellite ephemeris (independent of GPS broadcast ephemeris), Klobuchar model parameters tailored to the oceanic region, and satellite clock corrections using GPS data obtained from this limited deployment of collection sites is addressed. The primary degradation effects on stand-alone GPS positioning of Selective Availability (SA) are corrected using WADGPS, resulting in a significant improvement in position accuracy.

Keywords

1. Satellite navigation2. Differential systems3. Ionospheric delays
Type
Research Article
Information
The Journal of Navigation , Volume 47 , Issue 2 , May 1994 , pp. 146 - 158
Copyright
Copyright © The Royal Institute of Navigation 1994

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References

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