Started 1998, on going
Summary
When processing GLONASS carrier phases, the standard double-differencing (DD) procedure cannot cancel receiver clock terms in the DD phase measurement equations due to the multiple frequencies of the carrier phases. Consequently, a receiver clock parameter has to be set up in the measurement equations in addition to baseline components and DD ambiguities. The resulting normal matrix unfortunately becomes singular. To deal with this problem, some methods have been proposed in the literature. These methods, however, rely on the use of pseudo-ranges. As pseudo-ranges are contaminated by multi-path and hardware delays, biases in these pseudo-ranges are significant, which may result in unreliable ambiguity resolution. This research addresses a new approach that is not sensitive to the biases in the pseudo-ranges. The proposed approach includes such steps as converting the carrier phases to their distances to cancel the receiver clock errors, and searching for the most likely single-differenced (SD) ambiguity. Based on the results from the theoretical investigation, a feasible algorithm for GLONASS ambiguity resolution is developed.
Results
The testing results demonstrate that the proposed approach is reliable for use in the cases of GLONASS and combined GPS/GLONASS positioning.
References
Wang J (2000) An approach to GLONASS ambiguity resolution. Journal of Geodesy, (in press)
Wang J (1999) Modelling and quality control for precise GPS and GLONASS satellite positioning. Ph.D thesis, School of Spatial Sciences, Curtin University, 171pp.
Wang J, M Stewart and M Taskiri (1999) Integrating GPS and GLONASS for precise positioning: ambiguity resolution. Proceedings of the 6th South East Surveyors Congress, Fremantle, Nov. 1-6, pp. 230-236.
Wang J, M Stewart, M Taskiri and T Forward (1999) Ambiguity resolution for precise GPS/GLONASS positioning. Poster presentation at the 22nd IUGG General Assembly of the IUGG, Birmingham, July. (Abstract, Vol.A, p.407).
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