New BPSK, BOC and MBOC Tracking Structures

A. de Latour, G. Artaud, L. Ries, F. Legrand, M. Sihrener

Abstract:	Future GPS, Glonass, Compass and Galileo signals will use basically five modulations: BPSK, BOC, CBOC, TMBOC and AltBOC. This is the reason why future precise and robust GNSS receivers have to implement new tracking architecture compatible with all these signals. Most of the BPSK and BOC tracking architectures which have been widely studied up to now rely on well-known tracking techniques developed for BPSK modulations. Prompt, early and late replicas of the baseband signal are generated and correlated with the incoming signal. Correlation products are then used to compute for example noncoherent early-late processing (NELP) or dot-product (DP) discriminators. Some new techniques are focused on BOC tracking with subcarriers in phase and in quadrature. In this paper we present a different approach which consists in a tracking structure appropriate for BPSK as well as for BOC modulations. For this, prompt, early and late replicas of code are multiplied by in-phase and quadrature (I&Q) binary subcarrier replicas. The resulting tracking structure consists in 6 local replicas which are generated and then correlated with the incoming signal. This tracking structure enables to perform precise and robust measurement. For BOC modulations, the accuracy is given by the subcarrier processing and the robustness by the parallel code processing. This parallel code without subcarrier processing is unambiguous and performed continuously to detect any subacrrier cycle slip. Two numerically controlled oscillators (NCO) are sufficient for this technique. In this paper impressive code tracking performances of these new structures are presented based on analytical expressions and simulations in time-domain that account for additive white Gaussian noise and multi-paths.
Published in:	Proceedings of the 2009 International Technical Meeting of The Institute of Navigation January 26 - 28, 2009 Disney's Paradise Pier Hotel Anaheim, CA
Pages:	396 - 405
Cite this article:	de Latour, A., Artaud, G., Ries, L., Legrand, F., Sihrener, M., "New BPSK, BOC and MBOC Tracking Structures," Proceedings of the 2009 International Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2009, pp. 396-405.
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