How do GPS systems work

How does GPS work? Everything you need to know about the location system

Table of Contents

How does GPS work?

As the name suggests, the positioning system uses signals from GPS satellites that orbit the earth. Overall, the system represents an interplay of the satellites in space, the user's GPS-enabled device and receiving antennas on earth. The resulting position determination is simple: the satellites that orbit the earth constantly broadcast their current position using radio signals out. These signals hit a receiver on earth, which is located in a smartphone, for example.

The receiver needs at least the signals from three satellites to be able to determine the current location on earth. The location then results from the calculation of the position of the satellite and the time it takes for the signals or radio waves to travel from the satellite to the receiver. A fourth satellite allows the receiver's own position to be verified and clearly determined.

How accurate is GPS?

In general, it can be said: The more GPS signals a capable device receives, the more precisely the location can be determined. The receiver generally requires an antenna, a quartz clock, a memory and a processor in order to be able to process the GPS signals. As already mentioned, at least the signals from three satellites are necessary to carry out a location. A fourth signal specifies the location based on the time determination. In civilian use with smartphones and the like, GPS receivers now work with up to twelve satellite signals. Depending on whether the device also has GLONASS, Galileo or Beidou, the theoretical visibility is extended and even more radio waves can be received.

In the open air, visual contact between the satellite and the receiver is usually not a problem, as long as there is no bad weather front. However, external circumstances can affect GPS accuracy. The transmission of radio waves or reception is impaired by many factors, including satellite and clock errors. The result: sometimes strong deviations from the exact location.

Even concrete or stone walls only let the signal through weakly, so that GPS receivers cannot maintain a connection to the satellite in tunnels, for example. In order to be able to compensate for the errors, there are correction services such as the European EGNOS. These are satellites that do not change their position relative to the earth and constantly send correction signals to the earth. Every GPS chip receives this data by default.

Depending on the area of ​​application and the device, the location accuracy differs by far. GPS receivers in smartphones, for example, have an accuracy of around five to fifteen meters, which is sufficient for conventional navigation. In many professions, however, the exact determination of a position is fundamental, so that the accuracy here even amounts to centimeters.

GPS: the history of its origins

GPS - short for Global Positioning System or German: Global Positioning System - is a service that is not used for navigation in general, but specifically for determining positions. This is done with the help of satellites orbiting high above the earth. GPS is mostly used synonymously as a term for a location determination. In fact, however, it is the NAVSTAR GPS system, which has been developed by the US military since the 1970s. In the following years it became more and more important, has been considered fully functional since the mid-1990s and has consequently been opened for civil use. So nowadays it can no longer only be used in the military, but can be found on many everyday devices.

In addition to the common GPS, there are also alternatives from other countries. Russia opened access to its own GLONASS system in 2012. Galileo comes from the European side, while China has the Beidou satellite system. Depending on the built-in receiver, devices can also receive signals from the other satellite systems mentioned in addition to GPS.

GPS alternatives: Glonass, Galileo and Co. can do that.

Areas of application of GPS

Since GPS has been made publicly available since around 1995, the satellite-based system is now used in many areas of application far away from the military. Many everyday devices such as smartphones, fitness trackers or cars are equipped with GPS-enabled receivers. GPS is also an indispensable area of ​​application in photography, sports or seafaring. The location system makes the previously widespread city maps and maps largely superfluous, especially since more and more virtual map services such as Google Maps or Here are also offering their maps offline and mobile internet is no longer absolutely necessary for use - at least in the smartphone area.

Compared to maps, GPS systems offer the added value that they provide additional information than just the route to the destination. If desired, hotels, restaurants or bus stops located nearby can also be displayed.

GPS on the phone

Many apps require GPS on mobile phones. On the one hand, this enables cell phone location to be carried out, for example, if the cell phone or even a person has disappeared. Some mobile phone games also benefit from GPS, Pokémon Go or Harry Potter: Wizards Unite are worth mentioning here. Dating apps like Tinder or date suggestions also work on the basis of GPS data.

There are also numerous apps that require location authorization for no apparent reason. It therefore doesn't hurt to keep an eye on the corrections and to question them critically. For many users, the location data and the resulting movement profile are sensitive data.

How do you enter GPS coordinates?

Every place in the world can be determined using exact coordinates. They are divided into a degree of longitude and latitude. The information can vary, as you can see from the coordinates of Cologne Cathedral:

  • Degrees, minutes and seconds (GMS): N 50 ° 56 ′ 28.6008 E 6 ° 57 ′ 29.8116
  • Degrees and decimal minutes (GMM): N 50 ° 56.476680 E 6 ° 57.496860
  • Decimal degrees: (DG): N 50.941278 E 6.958281

If you have the coordinates of a place at hand, you have to enter a map service under both iOS and Android - Google Maps is an example - in the search bar. If you want to determine the position first, you have to hold down the location in the app until a red label appears, which marks the location. The coordinates will then be displayed in the search bar. Google Maps provides helpful information on how to determine GPS coordinates and how to enter them in a targeted manner.

Fake GPS location

In connection with GPS and location determination, one repeatedly stumbles over the question of whether GPS data could be falsified. This is often referred to as “fake GPS”. For whatever reason you want to take this step: An app is always required to confuse the GPS signal and generate a different location. Fake GPS apps with relevant names can be found in both the Google Play Store and Apple's App Store.

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