Institute of Geodesy Research Research Projects
Investigations of distance dependent systematic effects

Investigations of distance dependent systematic effects

Led by:  Dr.-Ing. Steffen Schön
Team:  Dr.-Ing. Steffen Schön
Year:  2006
Date:  12-01-11
Is Finished:  yes

GPS is a promising tool for real-time monitoring of deformations of slopes or large structures. However, remaining systematic effects in GPS phase observations after double differencing and application of apriori models affect the resulting coordinates. They complicate the proper separation of the actual deformations from pseudo-deformations induced by the systematic effects. It can be shown that for small monitoring networks only affine distortions of the network geometry are generated by the remaining distance dependent systematic effects, e.g. unmodelled tropospherical and ionospherical propagation effects, or satellite orbit errors. Hence, a generic correction model is given by a three-dimensional affine transformation involving a maximum of 12 transformation parameters. For the determination of these parameters, four high quality GPS stations are necessary which are not affected by the actual deformations to be monitored. Based on the analysis of network geometries of synthetic GPS networks and considering the physics of the GPS observations it is shown, that less than 12 parameters are sufficient for the computation of the corrections

Further investigations in this research project will be carried out concerning the following aspects:

  • Impact of the use of different satellites at the network stations
  • Impact of C/N0-based observation variance models
  • Impact of physical correlations between the GNSS observations
  • Detailed study of the matrix structure, transferring systematic effects form the observation to the coordinate domain.

The initial work in this research field was done during a Feodor-Lynen-Fellowship of Steffen Schön at EGMS at Graz University of Technology with Fritz K. Brunner as his host. He gratefully thanks the Alexander von Humboldt-Foundation for the support.