Evaluation of High Performance Multipath Reduction Technologies for Precise DGPS Shipborne Positioning

Gérard Lachapelle, A. Bruton, Jamie Hemiksen, M. Elizabeth Cannon, Chris McMillan

Abstract:	Two code multipath reduction technologies, namely METrM and MEDLLTM, were tested in DGPS shipborne mode to determine their effectiveness in this environment. The METTM and MEDLLTM technologies are designed to reject multipath delays of 15 m or more and their performance will be a function of the surrounding environment at the reference station and on the ship. In addition to intercomparing the METrM and MEDLLTM approaches, each was compared to the standard C/A Code wide correlator spacing and the semicodeless Y Code approach. The METTM and MEDLLTM technologies are used in NovAtel’s receivers. A pair of Ashtech Z-12 receivers were used to provide the C/A code and semicodeless results. The tests were carried out on a 1,600 tonne Department of National Defence vessel off the coast of Vancouver Island in May I995 over a period of several days. All receivers performed well and, for each receiver pair, the integer ambiguities were resolved to obtain a reference trajectory at the cm- level. These reference trajectories were then used to assess the code and carrier phase smoothed code solutions obtained with the above technologies. Under the prevailing multipath conditions, the code and carrier phase smoothed code position results with METTM and MEDLLTM were found to be more than twice as good as the corresponding standard C/A code results in terms of rms agreement. METTM and MEDLLTM outperformed the semicodeless Yl derived positions by some 25% to 70%. MEDLLTM was found to outperform METrM by about 15% in term of rms agreement.
Published in:	Proceedings of the 1996 National Technical Meeting of The Institute of Navigation January 22 - 24, 1996 Loews Santa Monica Hotel Santa Monica, CA
Pages:	399 - 406
Cite this article:	Lachapelle, Gérard, Bruton, A., Hemiksen, Jamie, Cannon, M. Elizabeth, McMillan, Chris, "Evaluation of High Performance Multipath Reduction Technologies for Precise DGPS Shipborne Positioning," Proceedings of the 1996 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1996, pp. 399-406.
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