Wait? Smartphones can figure out their location even without GPS? | The Easiest Explanation in the Universe | GPS Basics #16
"Why can I see my location on Google Maps on my smartphone even when I'm inside the house? I've always wondered about that."
This was a question from my wife, who had read my previous article about how "GPS doesn't work indoors."
It might be a simple question that a lot of people have, surprisingly...
So, the explanation of "why smartphones can determine their location indoors," which has been continuing since two posts ago, is finally getting to the core of the matter starting today!
And, this was supposed to be the long-awaited content.
But a comment from my wife after reading the previous two articles really hit home.
"No, it was too difficult and I couldn't wrap my head around it..."
O-oh, I see... (sweat)
For someone like me who delivers content under the concept of "the easiest explanation in the universe," that is quite a harsh piece of feedback.
I have taken this to heart and have decided once again to strive to make things even easier to understand...
Now, this time, we will move away from GPS a little and talk about how smartphones can actually determine their location using methods other than GPS.
A quick review of the previous post
Since there was feedback that it was "too difficult," I'll start with a rough review.
Last time, I explained that smartphone GPS uses a technology called "Assisted GPS," which has various benefits.
Specifically, it was like this.
Smartphone GPS can read the necessary data from the internet in an instant, rather than from GPS satellites, so it can determine your location immediately.
Furthermore, since it doesn't need to read the necessary data from GPS satellites, it can determine your location even with weak signals indoors.
Now, even with such Assisted GPS, it's not exactly omnipotent. In environments where GPS signals don't reach at all, it cannot measure your location.
But even in such environments, you can still see your location on Google Maps on your smartphone, right?
Smartphones can grasp their location even in places where GPS cannot be used
Let me start with the conclusion.
It's because smartphones have several ways to know their location even if they can't use GPS.
These technologies are collectively called "indoor navigation." Sometimes they are also called "indoor positioning," "indoor mapping," and so on. (You can forget the names.)
But basically, you can just think of it as "indoor navigation" being a catch-all term for ways to know your location indoors.
What kind of methods are there? Roughly four methods!
Specifically, what kind of methods are there? The main ones are like this.
Using signals from mobile phone base stations
Using WiFi signals
Using Bluetooth signals
Using various sensors built into the smartphone
The original purpose of cellular base station signals and Wi-Fi is for calls or connecting to the internet.
However, it's like saying, 'Just use whatever is available!'
First, let's look at 'roughly where am I?' using mobile base stations.
Actually, since this is something that 'should be obvious if you have a smartphone,' it might be a bit different from 'indoor navigation'...
You might wonder why I'm talking about this after mentioning 'indoor navigation' so much, but please let me explain it first as it is necessary background knowledge.
If you've ever opened a smartphone app like Google Maps, you've probably seen a display like this.
The blue dot representing your current location is surrounded by a large light blue circle
Sometimes a message like 'Accuracy is low' or 'Accuracy: Low' appears
This is your 'approximate location' calculated from mobile base station signals.
To explain very roughly how it determines your location, it works something like this.
Let's assume your smartphone is picking up signals from three base stations, A, B, and C, with roughly the same strength.
Since the locations of each base station are known, it takes the area in the middle of the three base stations and...
'Hmm, roughly around here?'
That's the image of how it determines your location.
Since it's a fairly rough method, you can't expect much accuracy at all.
Therefore,be careful when you open Google Maps and see a light blue circle! You might actually be walking on a completely different street!!
However, since smartphones are constantly picking up base station signals, the advantage is that as long as you aren't out of range, it can immediately tell you your approximate location even inside your house or a large building.
Actually, there are quite a few times when knowing your location this roughly is enough, right?
...Wait? Is there not?
Actually, this 'roughly around here?' is also necessary for Assisted GPS
Do you remember the talk about Assisted GPS? (It's okay if you forgot)
By using the 'Assisted GPS' mechanism on your smartphone, you can measure your location at high speed even with weak signals.
And what is needed first for this Assisted GPS is this 'roughly around here?' location.
I touched on this a little in the previous explanation, so if you noticed it, you're quite sharp!
In other words, the flow when using Google Maps on a smartphone is something like this.
Open Google Maps
Immediately get a rough location with a large light blue circle (location measured by mobile base stations)
A few seconds later, it becomes just a blue dot and you get a detailed location (location measured by Assisted GPS)
So,
You, who opened Google Maps on your smartphone to check the route to your destination.
If there is a light blue circle on the map, wait a moment!
Calm your impatient feelings and take a breath...
I recommend checking the route after confirming that it has become just a blue dot!
Well, as I wrote at the beginning, I explained this with a focus on being very easy to understand, but how was it?
Next time, finally! At last!!
...we will begin a full-scale explanation of the inner workings of "indoor navigation."