Getting Back on the Sidewalk: Doppler-Aided Autonomous Positioning with Single-Frequency Mass Market Receivers in Urban Areas

M. Bahrami

Abstract:	Motivated both by the continual availability and the centimetre-level precision of receiver generated (raw) Doppler measurements, even in severe urban canyons, this paper suggests a simple combination procedure of the noisy code-based pseudorange measurements and the receiver generated Doppler measurements. The objective is to smooth the code pseudoranges and push the accuracy of the code-based absolute positioning in a single-receiver autonomous mode in urban areas. It is shown that the proposed Doppler-smoothing of the code pseudoranges technique offers a modest improvement and is more robust and effective than that of the traditional measurement domain carrier-smoothed-code Hatch filter in difficult environments. While carrier tracking is continuous and free from cycle slips, the Hatch filter with an optimal smoothing window width can effectively suppress receiver noise and short-term multipath noise on code pseudoranges. However, the effectiveness of the Hatch filter is limited in urban areas and difficult environments, because carrier-phase measurements deteriorate easily and substantially due to blockages and foliage and suffer from discontinuities, cycle slips contamination and other measurement anomalies in such unfavourable environments. On the other hand, a receiver can generate Doppler shift measurements with centimetre-level precision as long as a signal is present. By taking advantage of the availability and the precision of raw Doppler measurements to ‘average out’ the code pseudorange noise, our early experimental results indicate that the technique improves the positioning accuracy even when the traditional measurement domain Hatch filter fails.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	1716 - 1725
Cite this article:	Bahrami, M., "Getting Back on the Sidewalk: Doppler-Aided Autonomous Positioning with Single-Frequency Mass Market Receivers in Urban Areas," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 1716-1725.
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