Performance Evaluation of GPS/Galileo Multiple-frequency RTK Positioning Using a Single-difference Processor

Wei Cao, Kyle O’Keefe, M. Elizabeth Cannon

Abstract:	Multiple-frequency measurements will be available from a multiple GNSS systems all over the world for civil users in the near future. This will greatly benefit GNSS applications with carrier-phase based precise positioning, e.g. real time kinematic (RTK) positioning. An interesting question to be answered in the multiple-system and multiple-frequency scenario is: which subsets of measurements from one or more frequencies on one or more systems will provide the best ambiguity resolution performance thus positioning performance for RTK users? Most existing software packages can only deal with current GPS L1 and L2 measurements and they are not easily adapted to deal with situations involving multiple-systems and multiple-frequencies. A flexible GNSS phase processor is developed to accommodate multiplefrequency measurements for future GNSS systems. This paper first introduces the design and development schemes of the single-difference processor. Since the Galileo and modernized GPS L5 measurements are not available at present, the data generation and processing strategy are briefly described as well. Then a set of simulation results is presented to compare the ambiguity resolution performance obtained when using various subsets of all of the observations available when using three-frequency modernized GPS in conjunction with Galileo. The results presented show that a single-frequency GPS/Galileo RTK system will perform better than a dual-frequency GPS L1 and L2 or L1 and L5 RTK system in the case that the baseline is short and the ionospheric errors are low. Dualfrequency GPS/Galileo also has superior performance when compared with a triple-frequency GPS RTK in terms of ambiguity resolution performance.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	2841 - 2849
Cite this article:	Cao, Wei, O’Keefe, Kyle, Cannon, M. Elizabeth, "Performance Evaluation of GPS/Galileo Multiple-frequency RTK Positioning Using a Single-difference Processor," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 2841-2849.
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