Structural deformation . . .

GPS has proven to be a useful tool for precision deformation monitoring applications, in both physical geodesy, and more recently for structural engineering. For continuous structural deformation monitoring (on an epoch-by-epoch basis) it is desirable for the measurement system to deliver equal precision in all position components, all of the time. However, the quality of GPS position solutions are heavily dependent on the number and geometric distribution of the available satellites. Therefore, the positioning precision is not the same in all three components, and during a 24-hour period the positioning precision varies significantly. This situation becomes worse when the line-of-sight to GPS satellites is obstructed due to trees or buildings in urban environments, reducing the number of visible satellites (often to less than 4). Locata is a new positioning technology that uses a network of ground based transceivers which cover a specific area with strong signals. This paper discusses the Locata technology and assesses its suitability for use in structural deformation monitoring applications, through an experimental trial at the Parsley Bay suspension footbridge in Sydney, Australia

Chris is a Fellow of the Australian Institute of Navigation,

Newcastle upon Tyne, UK. Joel has assisted in the development of the Locata receiver and testing of the Locata technology. Other current research interests include pseudolites, GPS receiver firmware customisation and high precision kinematic GPS positioning. Chris Rizos is a graduate of the School of Surveying, Th