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androidgpstriangulation
Ryan
Ryan

Reputation: 5546

when is cell tower triangulation used?

When networks are used for positioning, are these wireless networks that broadcast their ID, or are the networks actually the carrier networks, the ones you use when you make a call?

As far as I know, whenever I use the GPS, the cell tower are used to speed up the process, this being referred to as AGPS. This can occur even when wireless is disabled on the device.

When you use the Network provider, it uses wireless networks nearby without any interaction with the cell tower triangulation. In order to accomplish this, wireless has to be on.

Is this correct?

Upvotes: 5

Views: 1777

Answers (1)

Terence Eden
Terence Eden

Reputation: 14334

Yes, they are the same networks you make your calls on. Every cellphone tower has a unique ID.

Every ID corresponds to a specific location. The radius of that location could be a few meters to a few KM wide.

So, your AGPS takes the tower ID, looks it up in a database, and goes "I must be within 2 Km of xyz." That means it can (roughly) know which GPS are likely to be overhead and tune into them accordingly.

To get better accuracy, the phone can look at the signal strength of several towers. If the signal to Tower A is stronger than Tower B - it must be nearer A than B.

If it can see 3 or more towers, it can use the signal strength to work out roughly where it is.

Finally, some location aware devices will use WiFi to work out their location. If it knows that the WiFi network "Starbuck-1234" is on a certain street, it can use that information to give you an even more precise location.

Upvotes: 3

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