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 ...
In order to define basic parameters of a water stream, it is necessary to de-termine the location of characteristic field points that influence local hydrological conditions. The papers presents the methodology for performing geodesical mea-surements that are necessary to obtain data about water state in rivers and river bed profiles. The comprehensive process includes the following stages: field mea-surements, which include highly-accurate and stabilized minor control points; de-tailed measurements of selected relief points and water mirror level; finally, calcu-lations and indispensable analysis performed outside the field. Accuracy parameters should be in line with requirements defined in relevant regulations, norms and geodesical instructions.Data obtained from measurements are used in the preliminary stage of hydrological analysis preparation. The paper presents the procedure of field data collection applied in hydrological works, which includes selection of measurement point, methods of exact determination of river bed profile and density of measurements along profile cross-sections. These tasks are less frequent in geodesical practice, yet they may be significant for the group performing the measurements and may help to develop own methodology for high-accuracy tasks. ...
