Simulating GNSS Constellations – The GAMMA Signal Generator

摘要

The Galileo user receiver represents a key technology and is at the heart of the user segment. It is the main physical interface between the system and the user and transforms the Galileo Signal-in-Space into services for the citizen. Within the project GAMMA a consortium of nine industrial and research partners lead by Fraunhofer IIS of Nuremberg, Germany, are developing an assisted Galileo/GPS/SBAS satellite receiver prototype and a multi channel Galileo/GPS/SBAS signal generator to evaluate the performance of the receiver. The project has also investigated a number of assistance strategies to enhance the positioning accuracy and reduce the time to fix based on interaction with commercial 2G and 3G cellular networks, such as GSM and UMTS. Further work encompassed a study of indoor navigation capabilities, reconfigurable and hence reusable digital hardware components for GPS, SBAS and Galileo, assisted acquisition concepts, and, finally, low cost optimizations. The project has started in November 2005 and will run 24 months until October 2007. The initial work focused on market studies, application scenarios, specification and system design. Currently, the developments are almost completed and first tests have already been carried out. The paper puts special emphasis on the constellation simulator: The implementation, as well as performance benchmarks with respect to real satellite orbits will be