Renovated GLONASS: Improved Performances of GNSS Receivers

A.E. Zinoviev, A.V. Veitsel, D.A. Dolgin

Abstract:	The paper deals with changes in GLONASS since 2005: earlier publication [Zinoviev, 2005] serves as a reference point with respect to which updates related to GLONASS are given. GLONASS has been renovated dramatically over the period of last four years. Currently, there are 18 GLONASS-M satellites orbiting, thus GLONASS can be considered not just as GPS augmentation system but rather as a solo GNSS providing close to 24/7 service (up to 10 GLONASS satellites can be visible simultaneously at some periods of time). Also, GLONASS-only position can be computed at about 98% of all epochs over one day interval. Along with increased constellation, more important “qualitative” changes associated with the contents of GLONASS-M navigation data, improved reliability, availability of new civil L2 SA signal etc. took place. For example, GLONASS-M provides identification of ephemeris and time-and-frequency data without using any special methods. It is important for differential modes, in which corrections are computed with respect to broadcast navigation data. All such changes in GLONASS have a direct impact on GNSS positioning performances. In particular, this paper focuses on GLONASS-only positioning performances. It is shown that GLONASS RTK positioning performances are close to GPS RTK positioning performances in terms of accuracy. Also, GLONASS L2 HA (High Accuracy) (“L2 P-code”) and L2 SA (Standard Accuracy) (“L2 C/Acode”) signals are analyzed. Despite L2 HA signal is modulated with undocumented navigation data, there is a method to track this signal without having 0.5-cycle errors in carrier phase observables, even if L2 SA signal is not used. GLONASS is a must for state-of-the-art GNSS precise products. However, to make GLONASS useful at full, some interoperability issues need to be resolved. Perhaps, the most important among them is the issue associated with biases in GLONASS carrier phase double differences. This problem manifests itself when working with GNSS receivers of different manufacturers. It is demonstrated this problem can be solved efficiently by means of applying pre-defined corrections. In conclusion, it is noted GLONASS is the most rapidly deploying GNSS – as such it has well-defined directions for further improvement. The list of some of such improvements is given and, finally, outputs are provided.
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:	3271 - 3277
Cite this article:	Zinoviev, A.E., Veitsel, A.V., Dolgin, D.A., "Renovated GLONASS: Improved Performances of GNSS Receivers," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 3271-3277.
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