Generalized Discriminator and its Applications in GNSS Signal Tracking

J-C. Juang, T-L. Kao

Abstract:	The tracking of new-generation GNSS signals including Galileo and modernized GPS signals are considered to be more challenging than that with respect to legacy GPS signals. Typically, the tracking system is required to accomplish several, sometimes conflicting, objectives including acceptable tracking error under noise and multipath, fast response with respect to changing signal reception conditions, and ability to deal with nonlinearities due to multiple equilibria due to MBOC modulation. The design of the discriminator, which is an essential ingredient of the tracking loop, is deemed important as it affects the resulting sensitivity, bias, error, and ambiguities. To this end, several different discriminators including BPSK-like, subcarrier cancellation, multi-correlation, autocorrelation sidepeak correlation, BOC/PRN, and weighted discriminator schemes have been investigated. In the paper, a generalized discriminator is proposed with an aim to analyze most existing discriminators under the same framework. After presenting the generalized discriminator, its tracking performance under noise is analyzed. The risk of ambiguous tracking is then assessed and a condition for unambiguous tracking is established. Simulation results are then provided to illustrate the generalized discriminator in GNSS signal tracking. Finally, some comparative results on implementation are addressed. The investigation on generalized discriminator which put all potential design parameters under the same framework is believed to be beneficial to GNSS receiver designers in trading-off various issues including design complexity and achievable performance.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	3251 - 3257
Cite this article:	Juang, J-C., Kao, T-L., "Generalized Discriminator and its Applications in GNSS Signal Tracking," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 3251-3257.
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