Ship GPS Multipath Detection Experiments

G. Lachapelle, O. Julien, G. MacGougan, M.E. Cannon, S. Ryan

Abstract:	Ship multipath caused by the surrounding ship superstructure and water is a significant error source that can severely limit the reliability of GPS-derived navigation solutions. This is especially important given the low reliability of many current standard marine receivers (MacGougan and Liu, 2002). The magnitude of code multipath aboard a Canadian Coast Guard vessel was assessed using a series of onboard measurements with three receivers using different levels of correlator technology and two different antennas. The antennas were successively located on the upper mast of the ship. The three receivers tested consisted of a "standard" marine receiver, a high quality receiver set to use wide correlator methods and a high grade receiver using an advanced correlator technology. A fixed base station with known coordinates was used to accurately determine the reference position of the ship during the tests using differential carrier-phase measurements. Then, a residual analysis from a single differenced positionconstrained least-squares solution was performed in order to isolate pseudorange error whose main component is multipath. The data was collected over several days while the ship was in port in a static position. This enabled the detection and analysis of repeated day-to-day multipath. Two kinematic experiments were also conducted to study the differences with the static case.
Published in:	Proceedings of the 59th Annual Meeting of The Institute of Navigation and CIGTF 22nd Guidance Test Symposium (2003) June 23 - 25, 2003 Hyatt Regency Hotel Albuquerque, NM
Pages:	217 - 229
Cite this article:	Lachapelle, G., Julien, O., MacGougan, G., Cannon, M.E., Ryan, S., "Ship GPS Multipath Detection Experiments," Proceedings of the 59th Annual Meeting of The Institute of Navigation and CIGTF 22nd Guidance Test Symposium (2003), Albuquerque, NM, June 2003, pp. 217-229.
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