Böckmann, Sarah: Robust determination of station positions and Earth orientation parameters by VLBI intra-technique combination. - Bonn, 2010. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5N-23152
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5N-23152,
author = {{Sarah Böckmann}},
title = {Robust determination of station positions and Earth orientation parameters by VLBI intra-technique combination},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2010,
month = oct,

note = {In this thesis, it is shown that combining contributions of different VLBI analysis centers, a so called intra-technique combination, improves the robustness and stability of the final VLBI results. For this purpose, a refined combination method has been developed which is in many theoretical and practical aspects superior to combination approaches currently used for comparable geodetic combination tasks. For example, datum-free normal equation systems are used as input, which ensure that the contributions are not deformed by any constraints at all, and the same underlying terrestrial reference frame can be applied during the combination process. Furthermore, a statistically rigorous variance component estimation approach for the relative weighting of the contributions is used. The combination process implies detailed comparisons and analyses of the individual ACs' contributions. From these, as one of the outcomes of this thesis, several systematic differences between the individual contributions were detected and eliminated. The adherence to standards was considerably improved. The combination process itself reduces the analyst's noise and damps the impact of outliers. Validations with independent results of other space-geodetic techniques confirm a benefit of up to 15% more accurate results than from individual solutions.
Another aspect of this thesis is the general problem of any intra-technique combination, the correlations between the individual contributions. So far, the contributions of different ACs are always treated as independent data sets, although they have been derived from virtually the same set of original observations. It is shown that correlations between the individual ACs' contributions can be determined and rigorously taken in account during the combination process if the combination is performed directly on the level of the observation equations, instead on the level of normal equation systems. The main effect of considering these correlations is that the formal errors of the estimated combined parameters are considerably more realistic, but the parameters as such remain unchanged within their formal errors.},

url = {https://hdl.handle.net/20.500.11811/4229}

The following license files are associated with this item: