Global Systems
Global navigation satellite systems (GNSS) allow specialized radio receivers to determine their 3-D space position, as well as time, with an accuracy of 2–20 metres or tens of nanoseconds. Currently deployed systems use microwave signals that can only be received reliably outdoors and that cover most of Earth's surface, as well as near-Earth space.
The existing and planned systems are:
- Global Positioning System – US military system, fully operational since 1995
- GLONASS – Russian military system, fully operational since October 2011
- Galileo – On 21 October 2011 the first two of four operational satellites were launched the next two will follow in 2012. Expected completion is 2019
- Beidou navigation system – a planned project in China
- Indian Regional Navigational Satellite System – a planned project in India
Read more about this topic: Positioning System
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