How does a GPS work?
Undoubtedly, one of the great inventions created during the Cold War was the Global Positioning System, popularly known as GPS. Initially, GPS was designed for military applications used by intelligence services. Beginning with an incident in the 1990s, the United States established GPS for civilian applications. In this way, planes and means of transport could use GPS to determine their position.
Thanks to significant technological advances, today we only need a simple handheld GPS receiver to know, with a minimal margin of error, where we are in any part of the world. We receive all this information thanks to the more than 30 navigation satellites in continuous operation.
Is it necessary to have a GPS device?
The quick answer is no. GPS receivers have become so cheap and accurate that even low-end mobile phones come with one.
Today’s cell phones can even match professional equipment that uses GPS receivers. This is thanks to the fact that they operate with double frequency. In this way, they can essentially correct errors caused by atmospheric conditions and orbital position.
Although the mobile GPS is a great tool, keep in mind that mobile phones are not designed to give the exact position but to give you an approximate position as quickly as possible. This speed means that accuracy has to be sacrificed a bit (barely 10 meters of margin of error) to have a response in a few seconds.
If you have an old mobile or one giving you location errors and are interested in buying a GPS without spending a lot of money, we leave you a list of fully functional second-hand GPS. Remember that GPSs generally come with integrated software that continually updates their functions. So, give your pocket a break, and don’t be in a hurry to buy a GPS that is a few years old.
How a GPS works: a short explanation
Very briefly, GPS is a system made up of 3 parts: satellites, ground stations, and receivers. Satellites tell us where we are at any given moment. Ground stations use radar to make sure we are actually in that position. The receiver is continuously receiving signals from the satellites. After the receiver calculates your job from 4 or more satellites, you will know exactly where you are.
Main functions of GPS
GPS is a handy tool that is being integrated into more and more sectors. They use it from scientists, surveyors, pilots, and emergency personnel to the guy from Glovo who brings you food. GPS works 24/7 and under any weather conditions. The main functions where they are used are:
- Mapping. Create reasonably accurate maps of the world.
- Navigation. Move from one location to another without fear of getting lost.
- Tracing. Control the position in real-time.
- Location. Know where something or someone is.
- Timing. Measure time accurately.
Thanks to the different integrated functionalities, there are specific scenarios that are pretty common when we use a GPS:
- Entertainment. Various games include a GPS, such as Pokemon G.
- Transportation. To improve productivity, logistics companies use this tool to carry out studies to optimize routes, fuel efficiency, or driver safety.
- Health apps. They follow up on your physical activity and can obtain relevant information.
- Emergency. Being able to indicate precisely makes rescue work much easier, especially if the person does not know how to navigate.
How a GPS works: a detailed explanation
Satellite navigation is based on a worldwide satellite network that continuously transmits signals from medium Earth orbit. Users using satellite navigation typically use the 31 Global Positioning System (GPS) satellites operated and developed by the United States. There are different sets of satellites that also offer a similar service.
The set of all the satellites, whose primary function is to determine your position, is called Global Navigation Satellite Systems, for its acronym, GNSS. The satellite sets not part of GPS are mainly GLONASS, developed and operated by the Russian Federation, BeiDou, developed and used by China, and Galileo, developed and operated by the European Union.
For the basic GPS service to work, it is necessary to use at least 4 of the 31 satellites so that the receivers can capture the signal and interpret it correctly, with an accuracy of approximately 7 meters and 95% accuracy in almost any part of the surface—terrestrial, or at least close to it.
The satellites carry atomic clocks that provide the exact time to increase accuracy further. In this way, each time a satellite broadcasts a signal, the receivers can determine precisely what time the call was broadcast.
The signals that the satellites broadcast contain data that a receiver uses to calculate the location of the satellites and make adjustments as necessary to determine the position as accurately as possible.
One of the functions of the receiver is to take care of comparing the time difference between the time of reception of the signal and the time of emission to calculate the distance from the receiver to the satellite, all this taking into account the delay or propagation delay of the signal due to the ionosphere and troposphere.
Once it has all the data about the satellite’s range and the satellite’s location when the signal is sent, the receiver can calculate its three-dimensional position. It should be noted that without the atomic clock, the satellites would be unable to synchronize and could do an erroneous reading.
After reading all this, you might still wonder why using at least four satellites to calculate the location is necessary. Can’t you do 3? At least three signals from 3 different satellites are essential to calculate the three-dimensional position. The fourth satellite is to synchronize the other three thanks to its atomic clock. In this way, our receiver, be it a cell phone or a GPS device, does not need to have an atomic clock to calculate latitude, longitude, altitude, and time.