Development of a Context-Aware Vector-Based High-Sensitivity GNSS Software Receiver

T. Lin, C. O’Driscoll, G. Lachapelle

Abstract:	In a standard GNSS scalar-based receiver, GNSS signals are usually processed on a satellite-by-satellite basis using scalar-based tracking loops. In contrast, a vector-based based receiver combines the signal processing and the navigation solution into one step so that one tracking or processing channel can aid other channels via the navigation state; thus generally it has better sensitivity over a scalar-based receiver. However the gain due to the inter-channel aiding in a vector-based receiver is negligible for indoor applications. In addition to vectorbased tracking, longer coherent integrations are needed for indoor navigation. Although extending the coherent integration time for conventional standard tracking loops (DLL/FLL/PLL) and Kalman filter based tracking loops is possible, the robustness of the carrier phase tracking in these tracking loops remains an issue. In this paper, a combined approach of the block processing and centralized vector-based tracking is utilized for robust indoor navigation. A context-aware approach is used to optimize the processing load of the receiver and the measurement weighting to provide seamless outdoorindoor navigation. Cascaded Kalman filter vector-based tracking is used under open-sky conditions; block processing and centralized vector processing is enabled when the signal power drops, signal fading level increases, or the Kalman filter tracking loops have difficulty to maintain lock. The algorithms, implementation details, and performance of the proposed context-aware high-sensitivity GNSS software receiver and its ultra-tight version are presented in this paper. Based on the results shown, the proposed receivers have acceptable robustness and accuracy for indoor navigation.
Published in:	Proceedings of the 2011 International Technical Meeting of The Institute of Navigation January 24 - 26, 2011 Catamaran Resort Hotel San Diego, CA
Pages:	1043 - 1055
Cite this article:	Lin, T., O’Driscoll, C., Lachapelle, G., "Development of a Context-Aware Vector-Based High-Sensitivity GNSS Software Receiver," Proceedings of the 2011 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2011, pp. 1043-1055.
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