Assessment of GPS/GLONASS RTK Under Various Operational Conditions

R.B. Ong, M.G. Petovello, G. Lachapelle

Abstract: The real-time kinematic (RTK) positioning mode uses differential carrier phase ambiguity resolution to achieve sub-decimetre accuracy for numerous applications. In areas of signal shading, GPS measurements alone may not provide the necessary geometry to correctly resolve the ambiguities in a timely manner. The Russian GLONASS system, while currently only partially operational, can provide additional measurements. With a full constellation expected in early 2010, GLONASS is becoming an attractive option for augmenting GPS. However, the frequency division multiple access (FDMA) structure of GLONASS complicates ambiguity resolution. This paper presents a GPS/GLONASS RTK methodology that uses single-differenced pseudorange, phase and Doppler measurements to estimate the position. The GLONASS frequency differences are captured by an additional state. The ambiguities are then resolved in the double-differenced domain. The algorithm was tested for relative vehicle positioning. On the mountain highway, GPS/GLONASS single frequency data provided better horizontal accuracy than GPS-only dual frequency (1 cm vs. 2 cm RMS). In a residential area with overhead foliage, GPS/GLONASS dual frequency data provided sub-decimetre accuracy more often than GPS-only dual frequency (65% vs. 56% of the time). Ambiguity resolution was almost impossible in an urban canyon. GPS/GLONASS single frequency float solutions provided better accuracy and availability than GPS-only dual frequency (10 m RMS and 58% vs. 50 m and 52%).
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: 3297 - 3308
Cite this article: Ong, R.B., Petovello, M.G., Lachapelle, G., "Assessment of GPS/GLONASS RTK Under Various Operational Conditions," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 3297-3308.
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