Title: Satellite navigation - Wikipedia
Headings: Satellite navigation
Satellite navigation
Contents
Classification
History and theory
Applications
Global navigation satellite systems
GPS
GLONASS
BeiDou
Galileo
Regional navigation satellite systems
NavIC
QZSS
Comparison of systems
Augmentation
Related techniques
DORIS
LEO satellites
See also
Notes
References
Further reading
External links
Information on specific GNSS systems
Organizations related to GNSS
Supportive or illustrative sites

Content: The system can be used for providing position, navigation or for tracking the position of something fitted with a receiver (satellite tracking). The signals also allow the electronic receiver to calculate the current local time to high precision, which allows time synchronisation. These uses are collectively known as Positioning, Navigation and Timing ( PNT ). Satnav systems operate independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the positioning information generated. A satellite navigation system with global coverage may be termed a global navigation satellite system ( GNSS ). As of September 2020
[update]
, the United States ' Global Positioning System (GPS), Russia 's Global Navigation Satellite System ( GLONASS ), China 's BeiDou Navigation Satellite System (BDS) and the European Union 's Galileo are fully operational GNSSs. Japan's Quasi-Zenith Satellite System (QZSS) is a (US) GPS satellite-based augmentation system to enhance the accuracy of GPS, with satellite navigation independent of GPS scheduled for 2023. The Indian Regional Navigation Satellite System (IRNSS) plans to expand to a global version in the long term. Global coverage for each system is generally achieved by a satellite constellation of 18–30 medium Earth orbit (MEO) satellites spread between several orbital planes. The actual systems vary, but use orbital inclinations of >50° and orbital periods of roughly twelve hours (at an altitude of about 20,000 kilometres or 12,000 miles).