Summary:

The launching of ASG-EUPOS system in Poland in May 2008 resulted in a significant increase in the use of satellite real-time measurements in surveying. The parameters provided by the GPS/GNSS receiver in the scope of quality of the determined position are mostly unreliable. Moreover, the concepts of precision and accuracy are frequently not distinguished in their meaning and used as synonyms. The paper presents the results of the analysis of precision and accuracy in determining position in Real Time Network measurements using NAWGEO service of ASG-EUPOS system. An important aspect of the applied testing technology was the design of test point location and the use of accurate ground-based measurements for quality control of the reference coordinates of test points, which were calculated from the GPS static measurements. The conclusions from the tests were based on 4475 RTN measurements carried out in 149 test runs on 27 test points. Based on the results of the test measurements, high precision of the determined positions of the points in the RTN measurements was identified. However, their accuracy was significantly lower, particularly for the determined heights of the points. Tendencies were observed to obtain solutions with a few-centimeter biases that limit the possibility of increasing confidence regarding the quality of the results of point measurement based on the averaging of the RTN measurements repeated over the point.