One of the most fascinating forms of technology that people use every day, without giving it much thought, is GPS. People use GPS technology with the use of a maps application, in which they type in a designated address, and the application calculates the most efficient route. Incredibly, the phone can pinpoint the user’s current location and provide directions. However, there is a complex system of engineering, math, and physics working behind the scenes. In this writing, the author will attempt to simplify this complex system.
The Network of Satellites Above Your Head
To start, GPS systems rely on over 30 satellites that are in orbit over the planet. These satellites are arranged over the planet in a way that there are always at least 4 satellites that are in the same sightline. Each of the satellites is equipped with atomic clocks that are highly accurate, with the ability to track time in billionths of a second. The satellites are designed to send a radio signal without interruption, which includes the satellite’s current location over the planet, as well as the time the signal is transmitted.
The satellites are designed in a way that your phone will not send any signals to the satellites to calculate its location.
You might think that GPS does more than just be quiet and collect data to figure out its own position. But this is actually why GPS does its job even if there is no mobile signal.
How Your Device Measures Distance Using Time
The principle of GPS is actually quite straightforward: distance is equal to time multiplied by speed. Radio waves travel at the speed of light—fast, but not too fast to be measurable.
When a satellite sends a signal, your phone documents the exact time the signal is received. Because the signal is time-stamped, your device can do calculations to establish the travel time of the signal. If you take that time and multiply it by the speed of light, you can figure out how far away the satellite is from your device.
Signals from many satellites are continuously received by your phone. It is always refreshing to give periodic estimations of the distances to each of the satellites.
Why Your Phone Needs Multiple Satellites
One satellite is not enough to triangulate your position. If I can establish that I am a certain distance from one satellite, I can be anywhere along the surface of a giant sphere surrounding that satellite.
Now I have an idea of the visible surface area of this sphere. If I introduce a second satellite, I can determine that I am located at the intersection of one of the spheres from the first satellite and one from the second. However, there is still quite a large volume of open area with many possibilities.
With three satellites, your location becomes much more precise, essentially pinpointing your location to one of two points.
A fourth satellite clears up a very serious inconsistency. Your phone’s clock would be out of sync with the satellite’s atomic clocks. This time inconsistency, however minuscule, would throw the location off quite a bit. Having a fourth satellite in view allows your phone to align its clock to the correct time and resolve a definite location.
This is called trilateration, which is a process your phone does all the time to provide you with up-to-the-second location data.
What Makes Real-Time Tracking Possible
Real-time GPS tracking works because your device is always listening and recalculating. Your phone receives data signals from satellites once a second, and in some cases, even more frequently.
As you walk, drive, or ride a train, your phone always observes very slight changes in position from each satellite. These changes reveal your movement. This is how navigation apps know quite accurately not only where you are, but also the speed at which you are going and the direction in which you are traveling.
GPS data is also smoothed out with data combined from other sensors, including accelerometers, gyroscopes, and a compass.
Why GPS Is Sometimes Inaccurate
Your completed short response also needs to answer the question, “Why is using GPS in tunnels and dense cities more accurate than in other locations?” expanding on the above précis to answer the question.
Most locations where GPS works just fine. However, in dense cities or tunnels, where satellite GPS signals and location quirks make GPS distance measure probes; there is less signal interference.
Finding your position may take a little extra time. However, when that happens, your ability to use navigation will still be functional.
How GPS Works Without Internet
Many people assume that the GPS used in their phone is driven by the internet. That is incorrect. GPS satellites do not depend on cell service or wireless internet.
The flow of data on the internet does, however, make the GPS more efficient. When mobile phones are connected to the internet, satellite positions are preemptively downloaded. This allows phones to connect to their satellites more quickly, especially during the initial use of navigation software.
Your mobile phone will continue to pick up GPS satellite signals even if disconnected from the internet and may take longer to get an accurate lock on its position. However, GPS navigation will continue to function.
The Impact of GPS Technology on Modern Living
The impact of GPS technology on modern living is vast. GPS technology in modern life is used in navigation applications, fitness activity trackers, ride-hailing services, tracking deliveries, emergency services, and even farming to enhance the efficiency of crop planting. Moreover, it is used in aviation and maritime navigation and in the study of earthquakes and tectonic movement.
The frictionless life that GPS technology offers is a huge benefit to people. Being lost less, the ability to navigate new places with ease, and sharing real-time locations with others are some of the safety and convenience features.
People who understand GPS technology may be even more in awe of it. Considering the interaction of a few satellites, clock mechanisms, and mathematical computations, it is possible to pinpoint your location on Earth. This is science working in the background to defy impossibility.
