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SISNeT handheld receiver (based on an iPAQ PDA)

Signals used by SISNeT

SISNeT (Signal in Space through the Internet) uses signals from EGNOS, the European Geostationary Navigation Overlay Service.
EGNOS is the first step in the European contribution to the Global Navigation Satellite System, and a fundamental stepping-stone towards Galileo, Europe's own Global Navigation Satellite System. EGNOS is an augmentation system to the GPS (Global Positioning Satellite) satellite navigation system, which provides and guarantees navigation signals for aeronautical, maritime and land mobile Trans-European network applications.


Satellite broadcasting through geostationary satellites (GEOs) has proved to be an efficient strategy for avionic applications and other modes of transport. For some applications though, GEO broadcasting may have some limitations due to obstacles like buildings in cities or rural canyons can interfere with the GEO reception.

While the EGNOS messages will still be very useful for transport applications, a different transmission link may be needed to take full advantage of the EGNOS potential. For this reason, ESA had launched specific contract activities (through the Advanced System Telecommunication Equipment programme -ASTE-) to assess and demonstrate architectures where the EGNOS signal was broadcast through non-GEO means (e.g. FM or GSM broadcasting). In this context, ESA launched an internal project to provide access to the these messages through the Internet. This project is called SISNeT.

SISNeT receiver based on a GSM / GPRS terminal

SISNeT availability

In August 2001, the ESA GNSS-1 Project Office set up the first prototype of the SISNeT concept. This prototype uses a PC computer to implement the user equipment software. The connection to the Internet was achieved using a LAN environment (via a proxy server).

Since February 2002, the SISNeT service has been available to the users via open Internet through an authentication protocol (see the SISNeT User Interface Document - for more details).


In the past, some of the ESA contracts were aimed at developing EGNOS SISNeT-powered receivers and demonstrating what they could do. These contracts included:

  • Development of an integrated SISNeT receiver, containing a GPS receiver and a GSM / GPRS modem (in co-operation with GMV under ESA contract);
  • Demonstrations of SISNeT receivers embedded in cars and buses (in co-operation with GMV under ESA contract);
  • Integration of the SISNeT technology in professional software tools (in co-operation with GMV under ESA contract);
  • Development of a handheld SISNeT receiver, based on an iPAQ PDA (Personal Digital Assistant) (in co-operation with the Finish Geodetic Institute under ESA contract);
  • Development of a SISNeT receiver based on a GSM (Global System for Mobile communications) terminal (in co-operation with the Navocap society under ESA contract);

Monitoring the active satellites and the EGNOS broadcast status using the SISNeT User Application Software


Opportunities for SISNeT

The SISNET project can deliver significant benefits to the GPS land-user community. A user equipped with a GPS (Global Positioning Satellite) receiver and a GSM (or GPRS) modem can access the SISNET services and benefit from the EGNOS augmentation signals, even under situations of GEO blocking.
The combination of the power of EGNOS and the almost unlimited capabilities of the Internet offers the opportunity for the development of a multitude of applications for satellite navigation.
To stay in touch with the progress of SISNeT technology, please do not forget to periodically visit the ESA SISNeT website.


Learning EGNOS

The EGNOS book





List of acronyms


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