Handheld Internet-Based EGNOS Receiver: The First Product of the ESA SISNeT Technolog

Similarly to other Satellite Based Augmentation Systems (SBAS), EGNOS– the European SBAS – will broadcast augmentation signals for GPS through Geostationary Earth Orbit (GEO) satellites. GEO broadcasting is proved to be an efficient strategy for avionic applications and other modes of transport. For some applications, though, it may be of interest to complement GEO broadcasting through other transmission means. For instance, building obstacles in cities or rural canyons may difficult the GEO reception. In those situations, complementary real-time Internet-based broadcasting of the EGNOS signal is of major interest as a way to continue taking the most of the EGNOS potential, irrespectively of the user environment. In this context, the European Space Agency (ESA) has launched an internal project to provide access to the EGNOS test bed messages through the Internet. The product of this project is a new technology, called SISNeT (Signal-in-Space through the Internet). Thanks to SISNeT, any user with access to the Internet (e.g. through wireless networks – GSM or GPRS –) may access the EGNOS product, irrespectively of the GEO visibility conditions. In this paper, the first product of the ESA SISNeT technology is presented: an EGNOS / SISNeT handheld receiver based on an iPAQ Pocket PC Personal Digital Assistant (PDA), integrating a low-cost GPS receiver and a GPRS link to the Internet (in the form of PCMCIA cards). After a general description of this development, the receiver software is explained in more technical detail, and experimental results are presented. As it will be shown throughout this paper, this PDA-based device has confirmed that an EGNOS-SISNeT powered receiver significantly improves the accuracy obtained from a GPS-only receiver, remarkably in urban areas.