System developments
GPS, from the USA, is the best-known, and currently the only complete GNSS satellite system. Russia also runs its own GNSS, called GLONASS, which is reaching global coverage during 2011. The European Union (EU) has committed to developing its own satellite system known as Galileo. China is also developing a global system known as Beidou and India and Japan are developing their own regional systems.
Australia will be one of the few countries on earth with the ability to receive signals from all of these GNSS systems.
GNSS history
The early GNSS, GPS and GLONASS, were designed by the military for military use, with signals made available to civilian users from 1983. Early adopters of these signals included the survey, geodesy and aviation industries. These industries and their equipment manufacturers developed methods of improving the positioning accuracy achievable from the GNSS signals through techniques such as differential GNSS and Real Time Kinematic correction.
On May 1 2000 the United States set Selective Availability to zero on the GPS signals, which meant that they no longer introduced deliberate errors into the signals available to civilian receivers. This change improved the accuracy achievable by simple handheld GNSS receivers from about 100 metres to about 10 metres. This, in combination with decreasing costs for GNSS chipsets and handsets, opened GNSS use to the mass market, and made positioning, navigation and Location Based Services a target for consumer applications.
Current and proposed GNSS systems
There are a number of GPS and GNSS systems currently available or under development including:
- Global Positioning System (GPS)
- GLONASS
- Galileo
- Beidou
- Indian Regional Navigation Satellite System (IRNSS)
- Japanese Quasi Zenith Satellite System (QZSS)
The future
Fuelling growth in the next decade will be next generation GNSS that are currently being developed. Major components are the USA's modernised GPS (called GPS III), the Galileo system being developed by the European Commission (EC) and the European Space Agency (ESA), China's planned Beidou system and the revitalisation of the Russian GLONASS system.
Improving the accuracy and reliability for GNSS users requires third parties to run separate augmentation systems. These augmentation systems can be space-based such as the United States Wide Area Augmentation System (WAAS) and the European Geostationary Navigation Overlay Service (EGNOS), or ground-based such as the Ground-based Augmentation System (GBAS) developed for the aviation industry.
Higher accuracy augmentation is available through networks of Continuously Operating Reference Stations (CORS) linked together as a network; an example of this is Queensland's SunPOZ Network.
For further information on worldwide activities and trends in GNSS visit The United Nations mandated International Committee on Global Navigation Satellite Systems (ICG).
For further information on other GNSS activities in Australia visit the International GNSS Society.
Last updated 12 September 2011