Author(s)

T.H. Diep Dao, Paul Alves, Gérard Lachapelle

Department of Geomatics Engineering, University of Calgary, Canada.

Carrier phase-based differential GPS is commonly used for high accuracy RTK positioning because it effectively reduces the effects of spatially corrected errors such as orbital and atmospheric errors. The spatially correlated error reduction is a function of the correlated errors measured by the two receivers. Carrier phase-based single reference station (SRS) positioning is capable of providing cm accuracy for static positioning and dm for kinematic positioning under normal atmospheric conditions when the inter-antenna distance is less than approximately ten kilometres. However, under highly localized atmospheric activity, and/or with a longer inter-antenna distance, the residual differential error increases and the accuracy degrades. The University of Calgary MultiRef? multiple reference station (MRS) approach uses a network of GPS reference station to model the atmospheric conditions over a geographic region to reduce correlated measurement errors. This approach uses a conditional least-squares adjustment to predict the errors in the network area. This study focuses on an evaluation of the MultiRef? approach relative to the single reference station (SRS) approach in the observation, position and ambiguity domains. Long-term and short-term convergence accuracy tests are used to assess the effectiveness of the approach. The network used for this assessment is located in Southern Alberta, Canada. This is a medium scale network with baseline lengths ranging from 30 to 60 km. The results show a minor to significant improvement of the MRS method in all domains.

Multiple reference station GPS RTK, single reference station GPS RTK, least squares collocation, performance evaluation

T. Dao, P. Alves and G. Lachapelle, "Performance Evaluation of Multiple Reference Station GPS RTK for a Medium Scale Network," Positioning, Vol. 1 No. 8, 2004, pp. -.