Abstract

Global Navigation Satellite Systems (GNSS) play an increasing role in the field of science and geodesy which has demanded an upgrade in the National Positioning Infrastructure in Australia. These important GNSS reference stations sometimes have their antennas mounted on poles or other high structures. These support structures might expand or move under external effects such as diurnal & differential heating, and wind loading. If the GNSS antennas are mounted on these moving platforms the quality of their data might be affected and if these movements are small they could be undetectable due to presence of random noise in the GNSS data.

 

This thesis has attempted at designing various survey methods to allow the detection of these movements independent of GNSS observations. The concepts of deformation monitoring, monitoring methods and structural properties of towers have been explored to some depth as part of this study. It is expected that the concepts and ideas explained can be applied when monitoring lightening conductors, Locata antenna poles, light towers and possibly high voltage electricity stanchions.

 

Main objectives of this thesis

The main objectives of this thesis are to study deformation monitoring, and to design and test various survey methods to measure movements of a metal pole in relation to the building when external forces act upon it. The relative movement between the building and the pole is of much significance hence it is important to have an in-depth understanding of the deformation surveying concepts and developing survey methods that allow detection of the small movements with a high order of accuracy.

 

Also, the thesis is not so concerned about failure of tower structures but about the magnitude of the movement of its mounted antenna.  Therefore the focus is on measuring and analysing its motion independent of GNSS observations. The reason for seeking independent data is that the GNSS analysis may absorb some of the motion into other parameters. 



GNSS antenna on EE building roof, UNSW © A. Shahapurkar, 2011