Title: OPTIMAL DATA PROCESSING STRATEGY IN PRECISE GPS LEVELING NETWORKS |
Authors: Stepniak Katarzyna, Baryła Radoslaw, Wielgosz Pawel and Kurpinski Grzegorz |
DOI: 10.13168/AGG.2013.0044 |
Journal: Acta Geodynamica et Geomaterialia, Vol. 10, No. 4 (172), Prague 2013 |
Full Text: PDF file (2.5 MB) |
Keywords: GPS, precise GPS leveling, post-processing |
Abstract: GPS (Global Positioning System) technique has become a major tool in contemporary surveying and geodesy. This concerns
mostly measurements of horizontal point coordinates, where centimeter-level accuracies are usually required and easily
achievable. For the height component, however, these requirements are higher and millimeter-level accuracy is necessary. On
the other hand, the intrinsic precision of GPS-derived heights is clearly lower comparing to the horizontal components. This is
due to unfavorable satellite geometry, adverse effects of the troposphere or GPS antenna phase center offset and variations. In
order to overcome these effects one has to carefully model all the error sources and rigorously process the GPS data.
This paper presents studies on the optimal GPS data processing strategy suitable for precise leveling. This was done through
the extensive testing and selection of the most appropriate observational session duration, ambiguity resolution strategy,
network geometry, troposphere and ionospheric delay reduction methods, signal linear combination, elevation angle cut-off,
etc. The analyzed processing strategies were evaluated through the processing of a test network. The test network consisted of
19 monitored points and 5 control points, and covered the area of 20 km x 60 km. The obtained results show that the precise
GPS leveling with the selected optimal processing strategy allows for about 3 mm repeatability of height measurements when
processing 4-hour long sessions. In our opinion GPS leveling may serve as fast and cost-effective replacement of classic
geometric leveling, especially in applications where the heights in orthometric or normal height systems are not necessary.
This is the case in, e.g., ground deformation studies. |