GPS sensitivity analysis applied to non-permanent deformation control networks

This paper illustrates the surveys and the
results obtained in an experiment whose goal is to
evaluate the Global Positioning System (GPS) sensitivity
and accuracy for deformation control on non-permanent network of di fferent extensions. To this aim a high-precision device was properly built to set up known
displacements along three orthogonal axes of a GPS antenna. One of the antennas in the considered GPS networks was moved according to centimeter and sub-centimeter displacements; after careful GPS data pro-
cessing, it was evaluated whether these simulated deformations were correctly a posteriori detected and at which probability level. This experiment was carried out
both on a local (baselines ranging between 3 and 30 km)and on a regional (baselines ranging between 300 and
600 km) GPS network. The results show that in the local network it is possible to identify the displacements at a level of 10 mm in height and at a level of 5 mm in
horizontal position. The analysis of the regional network showed that it is fundamental to investigate new
strategies to model the troposphere; in fact, it is necessary to improve the precision of the height in order to correctly identify displacements lower than 60±
80 mm; on the contrary, horizontal displacements can
be evidenced at the level of 20 mm.

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