[angusgr]

The conclusion about a "general place at a general time" seems entirely true when you're on a highway, moving quickly and hopping infrequently to large distant cell towers. No wifi points anywhere close. Just like the chosen example.

I bet its entirely different when you're in any kind of built-up area. Wifi points every few hundred meters, small cell towers every kilometer or two. I bet in those situations, someone could derive a pretty close record of "your moves". Even if the individual points jump around, you're presumably hopping cells and seeing new Wifi APs every few minutes - even when you're just walking around your house or your office - and that data can be triangulated.

I think the OP is right inasmuch as Apple probably didn't set out to track users as much as keep track of connected wifi & cell APs. That doesn't mean the data won't be enough to track movements in urbanised areas.

[mercurio]

I'm not the author. But I believe the O'Reilly researchers claim that the co-ordinates logged are of the device itself. It is not clear at all that this is true and the author of this post presents some evidence that would suggest otherwise.

[angusgr]

Sure, the article is a reasonable refutation to that part of the O'Reilly claim, and that is an important fact to clarify.

The article goes further though, and claims it's "not 'recording your moves'" and is just a "general place at a general time". I don't you can say that point-blank. As stated, I think that it's going to be entirely location-dependent as to whether the database can be treated as a "record of your moves" or not.

[2muchcoffeeman]

The author says he was using his phone and the GPS often.

If they wanted to track your moves and you have turned on the GPS, why doesn't it just, y'know, use the GPS data? Instead Apple tries to track your moves using cell towers?

Seems like the only way this would be a record of your moves would be by coincidence.

[angusgr]

To quote from my original comment: Apple probably didn't set out to track users ... That doesn't mean the data won't be enough to track movements in urbanised areas.

Whether this is really a scandal, I don't know. But it certainly seems surprising to me.

[dedward]

My understanding is hte iPhone doens't actually have a GPS receiver in it at all. It only uses a fuzzily defined "assisted GPS" which is basically based completely on 3g towers.

They don't use the GPS satellites at all.

[angusgr]

AGPS is GPS satellites assisted by cell towers, and is in the iPhone 3G onwards. http://en.wikipedia.org/wiki/Assisted_GPS

The original iPhone had no GPS and always used cell tower triangulation. This varied a lot - I remember in Manhattan, NY it could track me almost to the street number; on the other hand I once turned it on in a moving car in rural NSW, Australia and it drew a circle approximately 500km in diameter.

[allwein]

The device location is not logged in this database at all.

What it does is log the locations of all cell towers that it can communicate with at a point in time. So for a given timestamp, there will be dozens of points logged. So while the data will be able to say "You were somewhere in downtown Pittsburgh at 1:59PM on Monday", it won't be able to say "You were at 517 Liberty Ave at 1:59 on Monday." Also, timestamps for existing towers are updated whenever they are mapped an additional time. So if I was downtown again on Thursday, no one would be able to tell from my data that I had been there on Monday.

See my previous comment in another thread for more detail:

http://news.ycombinator.com/item?id=2467895

[smackfu]

Does it record signal strength from the towers, which would allow triangulation?

[uuilly]

It should be possible to get a best fit curve between all the towers to get a more accurate position.

[iang]

Yep, it's called cell id location. I worked in mobile phone location about 8 years ago and you could find a rough position (about 200m radius IIRC) and we used it as a first pass. That was on GSM networks, 3G cells are smaller.

[metageek]

And the newer E911 requirements which kick in next year call for 100m accuracy.

[tmcw]

This entire thing is in the FAQ. http://petewarden.github.com/iPhoneTracker/#9

[mercurio]

The FAQ has nothing to do with it. Nobody is contesting that cell tower location information is being used. The differing claim is this: the O'Reilly researchers claim that the co-ordinates logged are those of the device itself and these co-ordinates are possibly calculated using cell tower triangulation, while this blog post claims that the co-ordinates logged are those of the cell towers themselves rather than the device.

[tmcw]

Until your location can be triangulated by enough towers, your location is a tower.

Also, they're not O'Reilly researchers - one is an astrophysicist from Exeter and the other's a developer from Color.

[smackfu]

Seems unlikely since there are a ton more dots on my map than there are cell towers around here.

[andrewcooke]

why does such a small difference matter?

[allwein]

Because for a given timestamp, the iphone logs dozens of cell towers. So while you might be able to tell I was in Pittsburgh on Monday, you won't be able to figure out what address I was at.

[andrewcooke]

but isn't the important thing whether or not these are public or private, and whether you have control over them? the precision of the location may affect some use cases, may not affect others, but doesn't strongly affect why this is important or not (on the other hand, it;s the kind of thing people can have a nerd fight over, which seems to be a big attraction...)