What is GPS?
- GPS is the acronym for the US owned Global
Positioning System that provides users with positioning, navigation, and
timing (PNT) services.
GPS satellites provide service to civilian and
The civilian service is freely available to all
users on a continuous worldwide basis.
The military service is available to US and allied
armed forces as well as approved government agencies.
- GPS consists of three segments:
Space Segment - Consists of a constellation of 24
satellites transmitting radio signals to users.
L1 Signal: 1575.42 MHz
L5 Signal: 1176.45 MHz
Control Segment - Consists of a global network of
ground facilities that track, monitor and analyze all GPS satellites.
User Segment - Consists of GPS receiver equipment
using the information transmitted by the satellites to calculate a three
satellite constellation is arranged into six equally-spaced
orbital planes surrounding the Earth.
plane contains four "slots" occupied by baseline satellites.
24-slot arrangement ensures users can view a minimum of four satellites from
virtually any point on the planet.
GPS satellties Orbit the Earth at an inclination of 55°
and an altitude of 12,550 miles (20,200 km).
satellite circles the Earth once every 11 hours and 58 minutes.
2011, three of the 24 slots were expanded, effectively creating a 27-slot
constellation with improved coverage for
most parts of the world.
GPS Space Segment configuration:
(click image above to refresh status)
- The GPS Control Segment consists of a global
network of ground facilities that track all GPS satellites, monitor their
transmissions, perform analyses, and send commands and data to the
- The current Operational Control Segment (OCS)
includes a master control station, an alternate master control station, 11
command and control antennas, and 16 monitoring sites.
- GPS Operational Control Segment as of May 2017:
- As of January 13, 2020, there were a total of 32
operational satellites in the GPS constellation (not including
decommissioned, on-orbit spares).
list of available GPS satellites. (status)
- Choose desired GPS Satellite (NMEA ID) below to
view current location:
Like the Internet, GPS is an essential element of
the global information infrastructure. The free, open, and dependable nature
of GPS has led to the development of hundreds of applications affecting
every aspect of modern life. GPS technology is now in everything from cell
phones and wristwatches to bulldozers, shipping containers, and ATM's.
GPS boosts productivity across a wide swath of the
economy, to include farming, construction, mining, surveying, package
delivery, and logistical supply chain management. Major communications
networks, banking systems, financial markets, and power grids depend heavily
on GPS for precise time synchronization. Some wireless services cannot
operate without it.
GPS saves lives by preventing transportation
accidents, aiding search and rescue efforts, and speeding the delivery of
emergency services and disaster relief. GPS is vital to the Next Generation
Air Transportation System (NextGen) that will enhance flight safety while
increasing airspace capacity. GPS also advances scientific aims such as
weather forecasting, earthquake monitoring, and environmental protection.
Finally, GPS remains critical to U.S. national
security, and its applications are integrated into virtually every facet of
U.S. military operations. Nearly all new military assets, from vehicles to
munitions, are equipped with GPS.