WARNING: Dexcom G7 and going out of Great Britain

[Bruce Stephens]

I'm not 100% sure that this would work

There was some suggestion in the reddit thread that it was using GPS. Or, I guess, the more general "location" which phones have (which include using nearby fixed wifi access points and mobile network towers).

 

[Satan’s little helper]

There was some suggestion in the reddit thread that it was using GPS. Or, I guess, the more general "location" which phones have (which include using nearby fixed wifi access points and mobile network towers).

GPS is taken from satellites, to the best of my knowledge. Data service is from the local masts or Wi-Fi connection, which give the IP.

Edit to add, 3 satellites to triangulate coordinates.

 

[Bruce Stephens]

GPS is taken from satellites, to the best of my knowledge. Data service is from the local masts or Wi-Fi connection, which give the IP.

Sure, but Google and (I assume) Apple have databases of fixed wifi access points and their locations and they can use those to help with location. (Same with mobile network towers.) None of this is perfect (access points can be moved, for example) but they can be cheap ways of getting location (though I think you need data access because such databases aren't stored on your phone).

Getting an approximate location makes GPS much faster (because you have a better idea of which satellites may be in sight).