Slashdot Mirror
Sensors Gone Wild
tulanian writes "forbes.com has an interesting article on networked, intelligent sensors. It mentions an experiment done by DARPA where several dozen magnetic sensors were scattered along a road and passing vehicles could be identified by their magnetic signatures."
The world's navies have been identifying ships using magnetic signatures for decades; sophisticated mines exist which can not only distinguish friendly ships from those of the enemy from their magnetic signature, but use a combination of of the acoustic and magnetic signatures of a vessel to identify a particular ship (e.g. to distinguish one Ticonderoga class ship from another). This enables the laying of a minefield that will ignore the signatures of low value units such as minesweepers, frigates and destroyers, and only explode when a particular enemy carrier passes overhead.
One imagines that an intelligence agency wishing to assassinate a foreign president/dictator could achieve similar success using the sensors described in the Forbe's article - they need merely tune the sensors to the signature of the target's limo, and lay them on a public road on the way to his residence.
A number of suburbs of Dallas, Texas (including Carrollton, where I work) are using computerized magnetic sensors to monitor traffic. They're temporary installations -- a box about 4" x 6" x 1" high is placed in the center of the traffic lane, and covered with a thick sheet of what looks to be asphalt-impregnated duct tape.
When they're done with the traffic survey -- 24 hours, typically -- the city engineers cut out the sensor, leaving the tape that was stuck to the ground. You'll see these squares all over town -- they don't seem to disintegrate for several months, even after heavy traffic driving over them. The busiest intersections have several of these leftovers.
A Dallas Morning News article a year or so ago detailed the city's use of the boxes, and noted that they could derive detailed information about the vehicles by their magnetic signatures. I didn't put 2 and 2 together, though, until Slashdot came to the rescue...
Dallas is one of the most insanely vehicle-as-status-symbol regions of the country (according to friends who have lived elsewhere). I thought that Carrollton was simply doing a traffic survey no different than the pneumatic roll-over count... but if you can tell a '82 Chevette from a brand-new Cadillac SUV, it adds a whole new dimension.
Anyone want to bet against the cities prioritizing road repairs based on relative driver income, as opposed to mere number of vehicles?
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.