A New Adaptive Scheme for High-Sensitivity GNSS Acquisition in Presence of Large Doppler Shifts

P. Esteves, M. Sahmoudi, N. Ziedan, M.-L. Boucheret

Abstract:	Increased sensitivity and reduced fast time to first fix (TTFF) are key performance indicators for GNSS receivers, which depend on the surrounding environment, receiver design and available aiding information. To reduce the effect of attenuations, dynamics and navigation data bits transition, the GNSS acquisition engines employ both coherent and post-coherent signal integration strategies, namely non-coherent and differentially coherent. Understanding the advantages and drawbacks of each post-coherent integration strategy is fundamental in the process of optimization of the acquisition scheme, as well as the effect of high-dynamics in both coherent and post-coherent operations. In this paper, we study three important issues of GNSS acquisition. First, we propose a closed form expression to quantify the effect of a linearly changing Doppler frequency on the coherent integration output. Second, we derive a formula capable of characterizing the sensitivity gain of a differential integration detector. Third, we compare the effect of dynamics on both non-coherent and differential integration. The main objective of this work is to combine these three contributions for overall optimization of the acquisition scheme. More precisely, we mitigate the effect of large Doppler errors without compromising receiver’s sensitivity and ideally without additional computational cost.
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:	28 - 40
Cite this article:	Esteves, P., Sahmoudi, M., Ziedan, N., Boucheret, M.-L., "A New Adaptive Scheme for High-Sensitivity GNSS Acquisition in Presence of Large Doppler Shifts," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 28-40.
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