April 20, 2011

I am in ur phone, logging ur position

This is pretty neat: turns out that the iPhone keeps a running log of your location.

Privacy concerns notwithstanding, I think what would bother me most about this is consumption of memory. There isn't all that much in an iPhone; why are these jerks using it up for a log file I don't need?

Yet another reason why, were I even interested in getting a cell phone (which I'm not) I wouldn't go with the iPhone.

UPDATE: Looks like the iPad does it, too.

Posted by: Steven Den Beste in Weird World at 08:34 AM | Comments (8) | Add Comment
Post contains 92 words, total size 1 kb.

1 Joining that article with the one about MI police silently raiding your phone info during traffic stops, and I'm an unhappy camper.

Posted by: Douglas Oosting at April 20, 2011 08:41 AM (sdWdc)

2 Good lord.  Yes, yes, technically your cell provider can mostly track your location whenever they want; its part of providing cell coverage.  There is no good reason at all why the manufacturer of the cell phone should be able to do so, as well.

Posted by: metaphysician at April 20, 2011 10:49 AM (hD30M)

3 I think it should be something like a megabyte or two a day, but it's easy to compress. A gigabyte would cover a few years, maybe more, potentially the lifetime of the phone, because it spends a while motionless.

Posted by: Pete Zaitcev at April 20, 2011 11:11 AM (9KseV)


Metaphysician, it is true that the phone company can track your position. But getting those records requires a court order.

Posted by: Steven Den Beste at April 20, 2011 11:26 AM (+rSRq)

5 SBB- Exactly, which is why the phone company being able to track you doesn't bother me.  AFAIK, that information is considered private, and can't be handed out without a court order.  This is apparently free for anyone who looks. . .

Posted by: metaphysician at April 20, 2011 12:11 PM (hD30M)

6 Storing GPS coordinates should be possible within 18 bytes. It's merely 2 9 digit numbers, according to this web page:

<a href="http://www.csgnetwork.com/gpscoordconv.html">GPS Latitude and Longitude Converter</a>.

(I'll ignore for the moment various compression schemes such as simply recording the change in position and such matters as altitude, or even storing the numbers as three integers instead of as a string of characters.)

(On second thought: you could store these as 10 bytes: one two-byte integer for the degrees, a byte for the minutes, and another two-byte integer for measuring ten-thousandths of a minute. You have to do it twice for latitude and longitude, but wait, there's more: latitude only goes from -90 to 90, therefore can be represented by a byte instead of an integer. So you can store a GPS-format location in 9 bytes without any sort of compression or delta scheme).

So storing your location every minute would take 9*60*24=12,960 bytes a day, or 4,730,400 bytes a year.

To put this in perspective, you could do four years of minute-by-minute tracking in about 19 million bytes, which is about the size of the .aiff file for the Outlaws' "Green Grass and High Tides" I have in iTunes. It's about .2% of an 8 GB Ipod touch's memory.

Posted by: pgfraering at April 21, 2011 10:18 AM (rVfMa)


They aren't storing GPS coordinates. If the GPS were being used constantly, battery life would suck.

As part of the cellular protocol, the cell sends its own coordinates as part of the initial connection handshake. The cell's announced longitude and latitude are what they're logging.

Now if they're stupid, then they're logging that on a fixed schedule (every ten minutes, or whatever). If they're smart, they log it only when it changes, i.e. when the network does a handoff.

Posted by: Steven Den Beste at April 21, 2011 10:31 AM (+rSRq)

8 Actually, if they were smart they wouldn't be logging it at all.

Posted by: Steven Den Beste at April 21, 2011 10:31 AM (+rSRq)

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