It’s not just the gear, it’s what it can do. I’ve always liked gear that can tell me where I am. In my formative years, that was maps, charts, compasses, and when I could get my hands on it, my dad’s Magellan NAV 1000. Now I’ve got two devices within arm’s reach that can tell me exactly where I am, and display it in a thousand different ways. The weird thing is, my iPad doesn’t even have a GPS receiver. How does that work exactly?
I re-watched this video and thought I sounded kind of…uninformed. So here’s the long version of “I think it uses wifi.”
Skyhook Wireless is a really interesting company. With considerably less fanfare than Google’s much-talked-about Streetview, they’ve managed to accomplish a feat of similar scope. They wardrove 70% of of the population centers in the US and Canada (and continue to do so, to update their database). Now they have a database of over a hundred million wifi access points (identified by their MAC address), and their associated geographic location.
Their service consists of two parts.
Software on your device scans for WiFi access points around you - it doesn’t have to connect to these, it just grabs the MAC address and signal strength of everything it can see. This information is then transmitted via Internet to Skyhook, and returned as position data. So in the above example, you’re picking up AP X and AP Y at about the same signal strength, putting you somewhere between them (in reality, you would need more than two to get an accurate fix, but you get the idea).
Any unknown access points are added to the database, making it self-healing and self-expanding.
This data is combined with cell tower triangulation (which works in a similar manner) and GPS to give you an almost immediate position fix on your device, followed up by increasingly accurate readings as the GPS kicks in after 30-60 seconds.
Privacy Issues
Awhile ago there was a scare amongst people who didn’t know how GPS works. They were concerned that having a GPS device in your car or phone would transmit your location, presumably to space. That was silly.
Skyhook actually does this, though. When it transmits data to the server, they know exactly where you are. They don’t record your location (or at least don’t admit to it), but they do keep track of hits on access points, and are even opening this data to developers.
It’s called SpotRank, and it allows developers access to data showing the number of hits on access points at a given time. Basically this shows the density of iPhone users in a given place at a given time. Right now there’s no way to tie any of that to a specific user. But that’s not a technical limitation, just policy, and I think a subpoena could probably change that.
There’s currently no way to opt out of any of this. If you use position data (maps, or any app that asks if it can use your location) on an iPhone, iPad, iPod Touch, some Nokia phones, or a number of Motorola products, you’re transmitting your location to a Skyhook server, along with the location and MAC address of every access point your device can see.
So just remember - when the machines take over, ditch your cell phone, fast.
