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X-Ray Vision Is Coming to Your Cell Phone

A surprisingly simple method using built-in wi-fi lets phones see through walls.
MIT researchers are working to bring short range radar to the masses. Photo: Flickr/BenFrantzDale.

Ready for x-ray vision on your cell phone? Good news for all you creepsters out there, because it's coming.

Researchers at MIT, using what is essentially a standard wi-fi transmitter, have created a device that can track movement through walls in real time.

It's got all kinds of interesting search and rescue, spying, and entertainment possibilities, but first let's talk about how it works. It's shockingly simple.


Your smart phone, or some other device, sends out a low-powered wi-fi signal through a wall, which reverberates around the room. It detects all the objects in a room, cancels out the static objects such as rugs, couches, and whatever else, and when the signal bounces back, uses the reflection of moving objects to generate a radar-like image on your screen.

Watching the video of their early tests, you're not exactly getting HD video. Dina Katabi, the researcher responsible for this sorcery along with MIT grad student Fadel Adib (read their paper here), says work is underway to generate higher res images that'll allow you to see individual body parts with greater technology.

"This technology is available. The way I imagine it is that it'll be available in your handheld devices," Katabi said. "The components and technology are very cheap. Basically, you can get x-ray vision through walls to see moving objects."

"You don't ever have to go inside that room, you don't even have to have been in that room in your life."

The tech works through standard drywall, wooden fences, and even concrete walls, though as you'd expect, the range and accuracy depends on what sort of wall you're trying to look through.

X-ray cell phone technology has been discussed before, but past efforts didn't utilize built-in wi-fi transmitters. More recently, researchers at the University College of London developed something similar, but a wi-fi receiver in the room you wanted to survey was also needed in order for it to work. Not so for Katabi's technology, which she'll present at the Sigcomm Conference in Hong Kong in August.

"The beauty of this is you can be on the outside of the room, you don't ever have to go inside that room, you don't even have to have been in that room in your life," she said.

The promise of an easy-to-use, short range radar- or sonar-like device will definitely be useful for law enforcement looking to storm a building, firefighters looking for people in a burning building, and search and rescue operators, but the tech should have use for the layperson as well.

"People are going to be interested in getting this x-ray power, we all want that," Katabi said. "If I stop at a gas station in a sketchy area and I want to enter the place, I can see if someone is hiding in the back room or if I'm walking around at night, I can see if someone is waiting around a corner or something."