What is GPS? (Global Positioning System)

GPS (Global Positioning System), is a satellite-based radio navigation system owned by the U.S government and operated by the United States Space Force. It is one of the global navigation satellite systems (GNSS) that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. Obstacles such as mountains and buildings block the relatively weak Global Positioning System signals.

The GPS provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, and makes it freely accessible to anyone with a GPS receiver.

The project was started by the U.S. Department of Defense in 1973, with the prototype spacecraft launched in 1978 and the full constellation of 24 satellites operational in 1993. Originally limited to use by the United States military, civilian use was allowed from the 1980s following an executive order from President Ronald Reagan. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of GPS Block IIIA satellites and Next Generation Operational Control System (OCX). Announcements from Vice President Al Gore and the White House in 1998 initiated these changes. In 2000, the U.S. Congress authorized the modernization effort, Global Positioning System III.


Elements of GPS

The three segments of GPS are:

  • Satellites: The satellites circling the Earth, transmitting signals to users on geographical position and time of day.
  • Ground Control: The Control Segment is made up of Earth-based monitor stations, master control stations, and ground antenna. Control activities include tracking and operating the satellites in space and monitoring transmissions. There are monitoring stations on almost every continent in the world, including North and South America, Africa, Europe, Asia, and Australia.
  • User Equipment: Global Positioning System receivers and transmitters including items like watches, smartphones, and telematics devices.

Uses of GPS

  • Tracing location and determining a position.
  • Easy to Navigation: Getting from one location to another.
  • Tracking: Monitoring object or personal movement.
  • Mapping: Creating maps of the world.
  • Timing: Making it possible to make precise time measurements.

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