Why not use wi-fi (wireless Internet) access points to track down stolen cars, bikes, purses and other valuables?
Many of Earth’s major cities are becoming saturated with wi-fi access points. It’s hard to find a public place in San Francisco, for instance, where a wi-fi device can’t detect a nearby access point.
Imagine placing a narrow wi-fi beacon device inside the frame of your bicycle. You tell the beacon that, every day at 4 a.m., the bike is locked up at your house. Next time the clock strikes 4 a.m., the beacon turns itself on and it makes note of which wi-fi access points it can “see” from your home. It remembers that these access points represent home. Then it turns itself off again. (Wi-fi detection drains a lot of battery power — the device stays off most of the time to save juice).
Two days later, at precisely 4 a.m., the beacon powers on and notes what access points it can “see.” If it detects one or more of the “home” access points, it turns itself off again. Two days later it does the same thing, and so on. We’ll call this state of affairs the beacon’s default mode.
During one of these early-morning access-point checks, if the device doesn’t detect a home access point, it switches into “stolen mode.” It powers on every 15 minutes and checks for any open access points. (Open access points are not encrypted, so anyone — and in our case, any beacon — can use them to connect to the Internet.)
When the device finds an open access point within range, it sends a message to a server. The message specifies which beacon sent it, as well as a unique identification number that specifies which wi-fi access point is being used. The message also includes a list of other access points that the device “saw” during its recent travels.
Software on the server connects to a database that stores the geographic locations of known access points. It uses this information to convert the list of access points recently “seen” by the beacon to a path on a map illustrating your stolen bike’s recent movement. It converts the beacon’s current access point to the beacon’s current location, which it marks on the map and converts to a street address. The server sends this information to your e-mail account — and to the police, if that’s what you want.
(Each time the beacon connects to the server, it also checks for commands that it’s supposed to follow. Via a password-protected Web interface, you can tell the beacon to switch from “stolen” mode back to default mode. You can set a new home location, and you can set a new time for it to check each day for its “home” access point fingerprint.)
This would provide essentially the same service offered by LoJack, an extremely expensive anti-theft system for cars. LoJack depends upon a beacon that’s hidden in a car. If your LoJack-equipped car is stolen, when you file a police report a radio signal is sent to the beacon that puts it into “stolen” mode, which causes it to repeatedly emit a signal over a special radio frequency. Police cars and aircraft equipped with special LoJack sensing computers can track this signal and follow it to the car. LoJack is quite expensive (Carsdirect.com sells the device for $695, for instance), and the real expense comes from the service: LoJack employees and police have to be trained to use the tracking equipment, and so on. (Other services based on Global Positioning Satellite and cellular phone systems are also quite expensive.)
Now that wi-fi is almost ubiquitous in many areas, we can create a system that allows people who live in those areas to track their stolen goods without LoJack and all of its overhead — at a tiny fraction of the cost.
But remember that new stolen-item-tracking technologies can be put to darker uses too. Such developments mean that almost anyone might have the power to plant tracking devices on unsuspecting people and vehicles.