How GPS Works (for dummies)

Posted by Adriano Teixeira In: Business, Technology

Here you are, alive and hopefully well in what multiple media along the years called The Future. Not impressed? Well, that may be because this is not your future, only your plain and seemingly slow present. Do you scoff at the advanced micro computer in your pocket? Are you unimpressed with driverless cars, 24 hours deliveries and drone technology? Well, chances are you are simply a user and not a “knower”.

If you are like me, you probably grew up watching your dad tinkering with the family car and fixing the washer, but somewhere along the way that attitude towards our surrounding technology got lost, I grew up knowing how to use almost anything without having the slightest idea of how it works.

This is pernicious in multiple ways, personally it makes me feel helpless and overly dependent on consumption. My mind recoils in horror when faced with something deeper than the User Interface that was designed to translate the World’s complexity into my lazy user based and overly entertained brain.

Do you feel like this yourself? Chances are some of you do, and now what? Should we wallow in our own growing self-fulfilling ignorance or are we going to do something about it?

I don’t know about you, but I want to change, I want to know more, understand more, and I’m going to start with a big part of my professional life, something I use everyday – GPS aka Global Positioning System.

It totally fits the profile, I work marketing at a Navigation Software company, It’s my job to know about the business, but there’s no real immediate need for me to know how it actually works, but my fresh perspective on life demands me to at least understand it enough to explain it in simple terms to another uninformed soul, so here we go.

The GPS system consists of 32 satellites that circle the Earth twice every 24 hours, although 8 of these are basically replacements in case of emergency. These satellites send radio signals that travel at the speed of light into your phone’s GPS receiver and to calculate your position anywhere on the Earth’s surface it needs to engage with 4 different satellites that will then use a process called 3D trilateration. To understand it just think of it this way, every satellite involved will determine a large spacial sphere in which you’re currently located. The first satellite lets it know you’re inside a sphere. The second satellite does the same as the first satellite and the intersection of the two spheres makes a circle. The intersection of a third satellite sphere with the previous circle will provide it with 2 points, and using a 4th circle provided by the earth’s surface, we now get the correct point of your location (the 3 spatial coordinates (latitude, longitude and altitude).

This constant and fast communication between the satellites and your device will track your movement in terms of direction and speed, but unfortunately this process alone wouldn’t be very exact for a number of reasons. You see, Albert Einstein discovered an interesting mechanism that he called the theory of relativity. Basically time moves faster to objects that are far away from gravity and that includes our satellite buddies, so they must include very precise (and expensive) atomic clocks, that are constantly updating your device’s regular quartz clocks with the more precise time (additionally, because of the above mentioned theory of relativity, orbiting atomic clocks get 38 microseconds ahead of ground clocks every day. If this wasn’t accounted for, your GPS location would progressively be off by 6 miles more every day).

So this is it, yes there are some omitted additional details that include fluctuations caused by the gravitational pull from things like the moon and the sun that need to be accounted for, but this is enough to give you an overall understanding of how the technology works and to sound like an informed and intelligent person at the dinner table. 

Here at NDrive we’re hoping you’ll find this information useful and that you’ll come out of this read a little more appreciative of GPS technology. Don’t forget to use Karta GPS for all your navigation needs.

Adriano Teixeira
Loves writing, except biographical information.