How does GPS work? Explained!
Hey friends, Happy Wednesday!
Let’s look at how GPS (Global Positioning System) works this week. I aim to write my newsletter issues in a way one can follow them while traveling on a bus, having a coffee, waiting for food, etc. Let's jump in!
Shoutout!
Thanks to the newsletter Today You Should Know. I grabbed the idea to include a form for you to enter the gadgets you’d like to learn about from here. Feel free to fill out the form using the button “ Submit Your Gadget“ at the top of this email and share the gadgets that you’d like to learn about. Thank you again!
Tweet of the week
I’m sharing a cool fact about gadgets every day on Twitter. And here is one of them for you
How does GPS work?
Figure 1: Common Intersection of 3 spheres are the 2 yellow dots you see
GPS Satellites: The Global Positioning System (GPS) consists of a network of satellites orbiting the Earth. These satellites continuously transmit signals containing precise timing information and location data using Radio waves.
GPS Receiver: The GPS navigation device you use, such as a smartphone or dedicated GPS unit, contains a GPS receiver. The receiver’s main function is to capture signals from multiple GPS satellites overhead.
Triangulation: The GPS receiver needs signals from at least four satellites to determine your location. (But why four satellites? We’ll see this soon) Each satellite’s signal contains two important pieces of information: the satellite’s location and the time the signal was transmitted.
Time Delay Calculation: The GPS receiver measures the time each satellite’s signal takes to reach it. Since the signal travels at the speed of light, the receiver can calculate the distance between itself and each satellite by multiplying the travel time by the speed of light.
Trilateration: Once the distances between the receiver and multiple satellites are calculated, the GPS receiver uses a process called trilateration to determine the user’s position. Here is where we need information from at least 4 satellites. In the previous step, we calculated the distance of the receiver from each satellite. Trilateration involves intersecting spheres or circles around each satellite. The point where the spheres intersect represents the receiver’s location.
a. Imagine the case of having information from only one satellite. For example, let the distance between the smartphone’s receiver and the satellite be 5000 miles. Using this information, we know the receiver (smartphone) can be at any point on a sphere of radius 5000 miles with the satellite as the center.
b. Now if we combine information from 2 satellites (2 spheres), the intersection point is basically a circle. So now we know that the receiver can be anywhere on the circle (marked as red in Figure 1)
c. Add a third satellite and the intersection point comes down to 2 points in space (marked with yellow dots in Figure 1).
d. To account for any errors in the receiver's clock, a fourth satellite is needed to provide additional timing information for error correction.
Error Correction: GPS signals can encounter errors due to various factors such as atmospheric interference or signal reflection. To minimize these errors, GPS receivers use a technique called Differential GPS (DGPS). DGPS compares the GPS signals received by the device with more accurate signals received by stationary reference stations. The receiver corrects its position based on the discrepancy between the two sets of signals.
Mapping and Directions: Once the GPS receiver determines the user’s location, it can overlay that information on digital maps. These maps, stored in the navigation device’s memory or accessed online, contain roads, landmarks, and points of interest.
Question of the week
Approximately, how far away from the Earth do you think are the satellites used for navigation systems positioned in reality? Reply to this email with your thoughts, and we’ll have a discussion.
I’ll give you a shoutout in next week’s email for correct answers :)
Gadget of the week
AI Video generation: Synthesia is an amazing tool in AI video generation. Using their intuitive online platform, you can create videos with human presenters by simply typing in text. You can choose between 125+ AI avatars (based on real actors) who can speak your words in 120+ languages.
Thank you for reading!
Have a nice rest of the week, and take care!
Until next Wednesday,
Chendur
