Concept of GPS: Global Positioning System-History, Applications & Benefits (Especially for GATE-Geospatial 2022)

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Concept of GPS

  • Global Positioning System (GPS) technology is a great boon to anyone who has the need to navigate either great or small distances.
  • This wonderful navigation technology was first available for government use back in the late 1970s.
  • In the past ten or so years, it has been made available to the general public in the form of handheld receivers that use this satellite technology provided by the U. S. government.
  • GPS formally known as the NAVSTAR (Navigation Satellite Timing and Ranging) Global Positioning System originally was developed for the military.
  • Because of its popular navigation capabilities and because you can access GPS technology using small inexpensive equipment, the government mad the system available for civilian use.
GPS Tracking System

Technology

  • The USA owns GPS technology and the Department of Defence maintains it. The first satellite was placed in orbit on 22nd February 1978, and there are currently 28 operational satellites orbiting the Earth at a height of km on 6 different orbital planes.
  • Their orbits are inclined at to the equator, ensuring that at least 4 satellites are in radio communication with any point on the planet. Each satellite orbits the Earth in approximately 12 hours and has four atomic clocks on board. During the development of the GPS system, emphasis was placed on the following three aspects:
    • It had to provide users with the capability of determining position, speed and time, whether in motion or at rest.
    • It had to have a continuous, global, 3-dimensional positioning capability with a high degree of accuracy, irrespective of the weather.
    • It had to offer potential for civilian use.

Significant Benefits of GPS

GPS has also demonstrated a significant benefit to the civilian community who are applying GPS to a rapidly expanding number of applications. What attracts us to GPS is:

  • The relatively high positioning accuracies, from tens of meters down to the millimetre level.
  • The capability of determining velocity and time, to an accuracy commensurate with position.
  • The signals are available to users anywhere on the globe: in the air, on the ground, or at sea.
  • It is a positioning system with no user charges that simply requires the use of relatively low-cost hardware.
  • It is an all-weather system, available 24 hours a day.
  • The position information is in three dimensions, that is, vertical as well as horizontal information is provided.

Using the Global Positioning System

Using the Global Positioning System (GPS, a process used to establish a position at any point on the globe) the following two values can be determined anywhere on Earth:

  • One՚s exact location (longitude, latitude and height co-ordinates) accurate to within a range of 20 m to approx. 1 mm.
  • The precise time (Universal Time Coordinated, UTC) accurate to within a range of 60ns to approx. 5ns.
  • Speed and direction of travel (course) can be derived from these co-ordinates as well as the time. The coordinates and time values are determined by 28 satellites orbiting the Earth.
Image Result for How Gps Determines a Location

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