How GPS Technology Really Works

The GPS (Global Positioning System) is the only fully functioning GNSS (Global Navigation Satellite System) both in and outside of the world.  Leveraging a network of 24 medium Earth orbiting satellites, the system enables a GPS device to process accurate microwave signals to determine time, location, speed and direction.

Created by the United States Department of Defense, the system’s official name is NAVSTAR GPS.  Contrary to popular belief, NAVSTAR is not an acronym, yet a name chosen by John Walsh, who was instrumental in the original launch.  The satellite constellation is managed by the 50th Space Wing of the U.S. Air Force, a rather expensive undertaking that takes an estimated $750 million per year to maintain. Despite the steep budget, GPS is totally free to the public and civilians equipped with the appropriate devices.

Basic Method of Operation

GPS receivers calculate position by measuring the distance between themselves and three or more satellites.  Because the signal travels at the speed of light, they measure the time delay between the transmission and reception of each microwave signal to provide the distance to each satellite.  These signals carry details regarding the satellites’ location and general system conditions, information that is known as almanac and ephemeris data.

By determining the position and distance of at least three satellites, the GPS device is able to utilize trilateration to accurately calculate its position.  Since receivers usually don’t have the benefit of perfectly accurately clocks, tracking multiple satellites allows them to correct internal clock errors, and thus, deliver more accurate results.

The Many Applications of GPS

GPS is now widely deployed throughout the world and has a number of beneficial uses.  It serves as a helpful tool for land surveying, map making, commerce and various areas of the scientific fields.   It has several uses in aviation and is advantageous in virtually every branch of the military.  GPS technology is also being increasingly used to deliver precise time reference for applications such as synchronizing telecommunications networks and studying earthquakes.

Types of Devices

GPS receivers are available in a wide variety of formats.  You will find the technology integrated into automobiles, mobile phones and even watches.  There also a number of dedicated devices such as those developed by leading manufacturers such as TomTom and Trimble.  Today’s units can be integrated with personal computers and other devices using serial connections such as Bluetooth and USB.  Consumers looking for more precise navigation will be happy to know that mass popularity has made these devices easier to find and afford.


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