What Is GPS and How Does It Work?

Everything you need to know about the global positioning system

Stock photo of a person sitting in a car with a tablet using a generic GPS location app.

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GPS-enabled devices are a vital innovation when it comes to the everyday task of navigating the expansive world around us. Navigation tech like in-car navigation systems and mobile navigation smartphone apps like Google Maps all rely on GPS to get us from point A to point B. But what is GPS and how does it work?

In this quick guide, we'll answer those questions and show you other, current uses for GPS that take it beyond simple driving directions.

What Is the Global Positioning System?

The Global Positioning System (GPS) is a United States-owned navigation system made of up of three main segments: the Space Segment, the Control Segment, and the User Segment.

The Space Segment is a navigation system of at least 31 satellites, 24 (or more) of which are usually in flight and operational. These satellites fly within Earth's orbit at an altitude of 12,550 miles. Each individual satellite usually circles the Earth twice a day.

The Control Segment is an international network of control stations that track, monitor, and maintain the satellites in orbit. These control stations can also send data or commands to the satellites. The Control Segment is made up of 16 monitor stations, two Master Control Stations (one main one and one alternate), and 11 command and control antennas (four ground antennas and seven Air Force Satellite Control Network remote tracking stations).

The User Segment is basically just civilians and our GPS devices (also known as GPS receivers because they essentially receive signals from the satellites in orbit and use that data to pinpoint our locations).

Who Invented GPS?

While there isn't a clear-cut singular inventor of the Global Positioning System, the overall consensus is that four main people can be credited with the development of GPS. The four people usually credited with the invention of GPS are: Ivan Getting, Bradford Parkinson, Roger L. Easton, and Gladys West.

According to Lemelson-MIT, it was Getting who first envisioned GPS as we know it today, as a concept involving the use of "a system of satellites to produce precise positioning data for rapidly moving objects such as missiles and airplanes." And Parkinson's contribution to GPS' development came afterwards, in 1972, when he took on the lead role in directing the United States Department of Defense's GPS program.

In this role, Parkinson was able to build upon Getting's original ideas and essentially brought those ideas to a successful conclusion as he led the "conceptualization, engineering development, and implementation" of the Global Positioning System. And by 1978, Parkinson's GPS development project, known as the NAVSTAR GPS system, had been completed and successful as the project's "first differential GPS systems were functional – and accurate within three meters."

Roger L. Easton also contributed to the development of GPS and has been called the "father of GPS" because of his particular contribution. According to TechCrunch, Easton's contribution was the result of solving a problem related to tracking "Earth-orbiting objects" like satellites. In an effort to synchronize the tracking stations' timing and enhance his tracking, Easton developed a "time-based" navigation system in which he "put highly accurate clocks in multiple different satellites, which would then be able to accurately determine the precise location of someone on the ground." Easton called this system "Timation" and the U.S. Department of Defense ended up incorporating a few of its features into the development of the Global Positioning System.

Lastly, but certainly not least, mathematician Gladys West is also credited for her contribution to the development of GPS. As Mental Floss notes, West's contribution was her work in developing a model of the Earth that included "variations in the planet's shape caused by gravitational, tidal, and other forces." West's Earth model is widely considered to be a foundational element of the GPS project.

How Does GPS Work and How Is It Managed

How the Global Positioning System functions is based on the relationship between GPS satellites and GPS receivers (read: GPS-enabled devices). According to Garmin, a GPS technology company, the Global Positioning System works when GPS satellites transmit "a unique signal and orbital parameters that allow GPS devices to decode and compute the precise location of the satellite."

From this transmission, GPS receiver devices are able to calculate the location of their users by measuring the "the distance to each satellite by the amount of time it takes to receive a transmitted signal" and then combining that with the distance measurements from several other satellites.

And so, in order to correctly calculate a person's "2-D position", which is just latitude and longitude, a given GPS receiver device would need to receive a signal from at least three satellites. Calculating a 3-D position, on the other hand, would also add in altitude and require the signal of at least four satellites. Usually, according to Garmin, most GPS receiver devices will receive and track the signals of at least eight satellites, but this number can vary based on your location and what time it is.

The Global Positioning System is owned by the United States and according to GPS.gov, the System is maintained and operated by the U.S. Air Force. The U.S. Air Force essentially "develops, maintains, and operates" the 24 current satellites that make up the System and the monitor and the control stations located throughout the world that are used to take care of the satellites.

Beyond Car GPS Systems: Other Everyday Uses for GPS

GPS isn't just for navigating your way home. There are many other everyday uses for GPS that you probably haven't ever considered. Here are a few examples:

Geocaching

Geocaching is a form of recreation that involves setting up treasure hunts; hiding "treasures" (usually small prizes and toys) in certain locations, then uploading maps online to have other people search for them with GPS devices (like smartphones or more expensive GPS units).

Child Safety

These days parents and schools are making use of GPS via wearables and mobiles with built-in location trackers to keep track of their child's location. Now, if your child gets separated from their class during a field trip, it's a lot easier to find them.

Electricity Access

You local power company probably uses GPS to keep track of power outages and their repairs. The use of GPS can help these companies quickly figure out where an outage is, and where and if repairmen are nearby to fix it.

Movies

Cinematography hasn't been the same since GPS became widely available for consumer use. Now, GPS is used for things like location scouting, to help find the best places to film certain movies. GPS can also be found in those big, sweeping, birds-eye-view camera shots in your favorite movies, because it's likely a GPS-controlled drone was used to film it.