What is GPS and how it works

GPS is a satellite positioning system that allows you to know the longitude and latitude of an object at any time

Devices with a GPS receiver inside are many: navigators, smartphones, tablets, smartwatches and watches, just to name a few. We use them mostly to keep track of our location and to get directions. We talk a lot about GPS, but most likely very few people really know how it works. What is GPS?

Let's start with the basics. GPS stands for Global Positioning System, so it is a global positioning system. With GPS, you can locate the longitude and latitude of objects and people. Everything happens with satellites that are stationed in Earth's orbit and allow you to know at any time the exact location of a place. The satellites contain an atomic clock that calculates to the thousandth of a second the time that passes from the request made by the GPS receiver to the answers obtained by the satellites themselves.

In the world there are several systems for global positioning. The most famous is the NAVSTAR acronym for Navigation System with Timing And Ranging Global Positioning System and is what we all call GPS. Created by the U.S. Department of Defense in the military, it has become famous for civilian use. The NAVSTAR system uses a total of 31 satellites. In addition to the system created by the U.S. there are also others: GLONASS stands for GLObal NAvigation Satellite System and is the positioning system used by the Russians. Formed by a total of 31 satellites, of which only 24 are working. Europe also has its own positioning system (GALILEO), active since 2016 and formed by 30 satellites. BEIDOU, on the other hand, is the system created by China and IRNSS the Indian one.

How the GPS system works

The GPS system is mainly based on the atomic clocks present inside the solar satellites. To understand how GPS works, it is best to give an example. There are 31 satellites stationed around the earth's orbit: at any given moment they send their position to the control towers. When a GPS receiver is activated, it receives information about the position of the various satellites. By triangulating the received data it is able to determine its own position. The geolocation is always very precise, at most there can be an error of a couple of meters, caused mainly by interference.

The Elements of GPS

To ensure the perfect functioning of GPS, three different instruments must work in perfect harmony: the space segment, the control segment and the usage segment.

The space segment consists of the satellites that are stationed around the Earth's orbit tilted at 55 degrees to the equator. Each satellite revisits the same point every 24 hours.

The control segment are the five centers that handle all the information sent by the satellites. The control segment stations are all located near the equator: in Colorado Springs in the USA, Hawaii, Ascension Island, Diego Garcia and Kwajalein. The most important control center is the one in Colorado Springs that corrects all erroneous information sent by the satellites.

The usage segment is nothing else than the GPS receivers present on Earth. For example smartphones, sat navs and watches.