Hänsel, F.; Ganzelmeier, L.; Becker, U.; Schnieder, E.:
Mobile Testbed for the Accuracy and Availability Measurement of Satellite Navigation Systems.
In: Möhlenbrink et al., Hrsg.: Proceedings of "Networks for Mobility" (Fovus), S. 30, ''9 2004. Networks for Mobility, 29.09.-01.10.2004, Stuttgart.


Safe operation control in non-guided traffic requires high availability and reliability of vehicle localisation technology. Normally the accuracy and availability requirements for vehicle localisation systems can only be met by complex multisensor systems comprising on-board and trackside components like odometers, gyroscope, transponder etc. Satellite-based localisation technology has in recent times been increasingly used in traffic applications, and GPS–based systems are already in operation. One of the most promising advantages for traffic is the fact that these systems provide absolute location information without requiring trackside equipment. However, satellite-based localisation requires the reception of signals from at least four satellites. But on many tracks or roadways, this visibility prerequisite cannot be fulfilled because of shadowing effects from the natural environment, buildings etc. This results in a considerable loss of localisation availability. At the Technical University of Braunschweig therefore a method has been developed within the "SATNAB" project, which allows satellite-based localisation using the signals from a single or two visible satellites. If we suppose a vehicle is travelling on a known roadway, its position can be determined by processing the current range between one visible satellite and the vehicle. This paper gives an overview of the methodologies used in order to analyse satellite navigation systems in general and satellite-based vehicle localisation systems in detail. The structure of the used mobile testbed in form of a measurement vehicle is presented in details. The build up equipment allows qualifying single satellite receivers up to complete vehicle localisation technologies. In addition to this detailed description, the intended applications for the further use of the vehicle are addressed.