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Have you ever wondered how satellites can track mobile phones?
It seems like they’re so far away, yet they can be accurate within about 15 meters.
Just how is that done?
Based on that, your phone’s GPS receiver calculates your location in latitude and longitude.
It can also calculate your current speed, based on the time between readings and distance covered.
So how exactly does this trilateration thing work?
How Do Satellites Track Mobile Phones?
Imagine a cone extending down from each of the three satellites covering your location.
These cones make ellipses, close to circles, when the hit they Earth.
Now, you have three intersecting circles.
The centers of those circles are then used in a trilateration equation to determine roughly where you are.
The point where all three circles intersect is your position.
Let’s see how that might look in a simplified view.
The actual equation is more complex than the scope of this article will allow.
However, I think this will give you a good high-level understanding of how it all works.
Originally, the GPS receivers could only use data from 4 or 5 satellites at once.
Now they can use as many as 20.
What can stop it from being tracked is anything that is going to block the line of sight.
So it isn’t a foolproof system.
Not all phones have the hardware to be tracked by satellite, but many do.
BlackBerry and Treo are popular brands of cellphones that have satellite-trackable models.
Same principle, slightly different technologies.
Once your phone has calculated your position, how does it let anyone else know what that position is?
I bet one of our readers has an answer to this question.
Personally, I don’t see it.
How many cellphones are there in the world?
What kind of massive server farm would you should probably keep track of all that?
There are situations of emergency where this process is sped up and may not include the full warrant procedure.
Image Credits: 50th Space Wing [Broken URL Removed],Wikimedia Commons
