Everyone knows GPS and probably most of them use it in the car or on their smartphone. But what does the term actually stand for and how does the technology work?
GPS stands for Global Positioning System. It is a navigation system for which 24 satellites orbit the earth in six different orbits at an altitude of 20,000 kilometers. With the help of satellites, the position of an object or a person on earth can be determined with relative accuracy.
The determined position is also synchronized with speed and time information via GPS. This means that GPS can be used to determine at what location and at what time an object or person is moving and how fast. The technology is now used in every modern smartphone and forms the basis for popular services such as Google Maps.
Trilateration – how GPS calculates position
In addition to the satellites, GPS also includes ground control stations to control and steer the satellites. In order to be able to use GPS, you need a GPS receiver, which is now found in every smartphone, smartwatch or navigation device.
The GPS receiver reads the microwave signals sent out by the satellites and then calculates its own position. The technology behind it is called trilateration. A satellite’s signal creates a sphere whose radius is measured by the receiver. The receiver repeats this with a total of three satellite signals. This gives him two intersection points, from which he chooses the one closest to Earth – his own location.
GPS determines the speed
If the GPS receiver is in motion, the distance to the satellites changes and the new position is calculated. Based on the new position and the time, the receiver determines the speed at which it is currently moving.
However, to calculate the position, the GPS receiver must receive the signals from at least four satellites. Three are used for trilateration, the fourth is used to check that the position calculation is correct.
By determining the position using GPS, it is possible to create very precise maps and take time measurements. In addition, a route to a specified destination can be determined – the basis for every navigation device in the car. Ultimately, the “Global Positioning System” can also be used to track or monitor objects and people.
Developed by the US military
GPS is from US military, which initially used the system’s tracking capabilities to navigate submarines. In 1983, the US military made its technology publicly available, but retained full control over all GPS data. It wasn’t until this control was abandoned in 2000 that GPS use boomed.
Even though GPS has been constantly improved over the years and more precise position calculations are possible than before, work has been done on various navigation systems in the past. For example, the EU developed the Galileo satellite system. China also has its own navigation satellite system called Beidou.