A Novel Parallel Carrier Tracking Architecture for Weak GNSS Signals

Muhammad Tahir and Letizia Lo Presti

Abstract:	The problem of designing robust architectures to track global navigation satellite system (GNSS) signals in harsh environments has gained high attention. The classical closed loop architectures, such as phase locked loops (PLL), have been used for many years for tracking, but in challenging applications such as weak signal and high dynamics, their design procedure becomes intricate. In weak signal conditions, the only option available is to increase the coherent integration time for successful operation of tracking loops. However, it is not possible to increase the integration time beyond certain limits which are set by different factors, one of them is the stability of the classical closed loop schemes. In this paper we investigate an alternative architecture for the tracking of weak GNSS signals where we aid the PLL from an independent architecture called quasi-open loop frequency estimator. The real motivation behind such a scheme lies on the fact that if we provide frequency aiding to PLL we can reduce the effective loop noise bandwidth which in turn allows us to increase the coherent integration time without worrying about loop instability problem. Simulation results are presented which indicate the feasibility of using such type of scheme in weak signal conditions where we can increase integration time in PLL scheme to larger extent which otherwise are not possible in classical closed loop schemes.
Published in:	Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012) September 17 - 21, 2012 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	41 - 46
Cite this article:	Tahir, Muhammad, Presti, Letizia Lo, "A Novel Parallel Carrier Tracking Architecture for Weak GNSS Signals," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 41-46.
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