A New Unambiguous Tracking Technique for Sine-BOC(2n,n) Signals

Zheng Yao

Abstract:	Several signals of the new global navigation satellite systems such as Galileo and modernized GPS use a new modulation type, i.e. the binary offset carrier (BOC) modulation. This modulation provides these signals with enhanced robustness against multipath, and increases the measurement precision. However, BOC modulation presents some drawbacks. Besides other drawbacks, ambiguity problem in code tracking is the most severe one. Since the BOC modulated signal has a multi-peak autocorrelation function, the tracking loop can lock on a side peak of the correlation envelope. The tracking process has to be able to cope with this problem, otherwise the loop may potentially gives biased measurements. In order to solve the ambiguity problem, in this paper, a novel unambiguous tracking technique is proposed. This technique is suitable for sine phased BOC(2n,n) signals, which is a specific family of BOC signal and has been used for modernized military GPS signal, M-code signal. The proposed technique is based on a pseudo correlation function. It completely removes the side peaks from the correlation function while keeping the sharp main peak, and has a well noise mitigation performance and an average multipath performance. This paper first gives an overview of BOC modulation, including the concept and some main characteristics of BOC modulation. Then, the ambiguity problem is described with a brief review of some existing typical solutions. Next, we discuss the details of the proposed method. The subsequent section comes to the tracking and multipath performance evaluation. Finally, with a concise summary some conclusions are drawn, including some prospects for further work.
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:	1490 - 1496
Cite this article:	Yao, Zheng, "A New Unambiguous Tracking Technique for Sine-BOC(2n,n) Signals," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 1490-1496.
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