About SISNeT
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) and GLONASS satellite navigation systems, which provides and guarantees navigation signals for aeronautical, maritime and land mobile Trans-European network applications.

Since January 2000, a pre-operational signal of EGNOS has been available through the so-called EGNOS System Test Bed (ESTB). The ESTB is a representative real-time mock-up of the final EGNOS system.

EGNOS will broadcast their wide-area / integrity message through geostationary satellites. The ESTB (EGNOS prototype) is already broadcasting the EGNOS message through the Inmarsat III AOR-E satellite. Broadcast through the Inmarsat III IOR satellite is also planned in 2002.

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 because building obstacles 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 has recently launched specific contract activities (through the Advanced System Telecommunication Equipment programme -ASTE-) to assess and demonstrate architectures where the ESTB signal is broadcast through non-GEO means (e.g. FM or GSM broadcasting). In this context, ESA launched an internal project to provide access to the EGNOS test bed 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 open Internet through an authentication protocol (see the SISNeT User Interface Document - version 2.1 and above - for more details).


ESA has recently developed three SISNeT-powered applications. These applications anable:

  • Real-time monitoring of the ESTB performance through the Internet
  • Real-time analysis of the ESTB messages
  • Real-time monitoring of the ESTB performance and SIS status through the World Wide Web. To access this service, click here.

Some of the current ESA contracts are aimed at developing EGNOS SISNeT-powered receivers and demonstrating what they can do. These contracts include:

  • 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 ESTB 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.


Last update: 8 July 2002