Creating Virtual L2 GPS Data Using a Combination of L1 Receivers and L1/L2 Reference Receivers

Gethin Roberts, Emily Cosser, Xiaolin Meng and Alan Dodson

Abstract:	Single frequency receivers are typically around half the price of dual frequency receivers. One of the major advantages that dual frequency receivers have over single frequency ones is that an on the fly (OTF) search can be performed quickly, due to the combination of L1 and L2 data resulting in the wide lane phase observable. Research is underway at the University of Nottingham whereby dual frequency reference GPS receivers are used to determine the characteristics of the ionosphere that the GPS signals have passed through. The information is then used in combination with a single frequency receiver located close by to create virtual L2 carrier phase data for that receiver. This paper details and discusses the theory as well as field trials and results obtained. Real and virtual L2 data is compared before and after processing, in static and OTF manners. The virtual L2 is very precise and initial results show that the virtual data is good to a few hundredths or thousandths of a cycle, trials are still underway to assess whether this level of precision is enough for an OTF search to work. Initial tests (with a known L2 start value) suggest that the search does work. This data will be incorporated into the bridge deflection monitoring project underway at the University of Nottingham, where the reference GPS receiver is located close to the monitoring GPS receivers upon the bridge.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	1408 - 1413
Cite this article:	Roberts, Gethin, Cosser, Emily, Meng, Xiaolin, Dodson, Alan, "Creating Virtual L2 GPS Data Using a Combination of L1 Receivers and L1/L2 Reference Receivers," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 1408-1413.
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