When was the last time you used a navigation app?
How many of your apps have asked you for a location permission?
^ not an actual pop up 😂
All location functions on your phone are possible thanks to a great technology called GPS
(Global Positioning System)
So, where did this awesome technology come from? And how does it work?
🤔
Like most modern technology, GPS traces its origins to the military
The earliest version goes back to the Sputnik era when the Soviets sent the first satellite to orbit
The soviets tracked the Sputnik with shifts in its radio signal. This is known as the Doppler Effect
As a response to the Soviets, the US Navy started conducting series of experiments on
Satellite Navigation
In the mid 60s the Navy was able to accurately track its submarines with 6 satellites orbiting the poles
🛰 🛰 🛰 🛰 🛰 🛰
In the early 70s, the
Department of Defense
wanted a standardized and stable navigation system. They started investing in researches in this area.
A system called Navigation System with Timing and Ranging (NAVSTAR) was born in 1978.
This system is what we call
GPS today 🙌
1993: The system became fully operational.
U.S. committed to maintaining 24 GPS satellites at any time (and 7 satellites as a backup).
1994: The FAA and Bill Clinton told airlines around the world that they can use the technology FREE of charge
1998: Al Gore announced a plan to make GPS open to the public.
What about
the masses?
2000: GPS becomes fully commercialized ...and the rest is history
Back to the original question.
How does it work?
How does it know where you are?
🤔
Each GPS Satellite sends its location and time
🛰
When a receiver (like your phone) gets the signal, it can calculate how far the satellite is from it.
How? You asked?
Well...Do you remember the distance formula? 👀
distance = speed x time
This distance will be the radius of a circle around the satellite 🛰
In this case speed is the speed of light and time is how long ago the signal was sent (Remember satellites send their location and time).
However, one satellite alone cannot determine your location.
🛰
Where
you at
though?
But 3 satellites can.
🛰 A
As far as Satellite A knows, you can be anywhere in this red border
But 3 satellites can.
🛰 A
🛰 B
Second satellite reduces your location to 2 places (the intersections)
But 3 satellites can.
🛰 A
🛰 B
🛰 C
With 3, your exact location is cracked.
But Earth is 3D. We'll need a 4th satellite to verify the altitude (also time)
🛰
So at any given time, you are followed by 4 satellites
🛰
🛰
🛰
Next time you open an app or game that takes advantage of location, think of this incredible history of GPS
Thanks
for your time!
☕️
#JebenaStories
How GPS Works?
By Jebena ☕️
