MIT Researchers Can See Through Walls Using Wi-Fi

itwbennett writes "MIT Professor Dina Katabi and graduate student Fadel Adib have developed a system they call Wi-Vi that uses Wi-Fi signals to visualize moving forms behind walls. How it works: 'Wi-Vi transmits two Wi-Fi signals, one of which is the inverse of the other. When one signal hits a stationary object, the other cancels it out. But because of the way the signals are encoded, they don't cancel each other out for moving objects. That makes the reflections from a moving person visible despite the wall between that person and the Wi-Vi device. Wi-Vi can translate those faint reflections into a real-time display of the person's movements.'"

Re:in other news

[solidraven]

Yes sure, everybody has a field service unit spectrum analyser that goes all the way down to -150 dBm in their hotel rooms!!!! Fact is that there are a lot better ways to track somebody. Radar isn't exactly something new either. I've built radars out of scrap minicircuits components that I found in my desk drawers, and even without trying you could see faint movements through walls on short ranges if your receiver's noise figure is sufficiently low.

Re:NSA Use

[Trepidity]

When it comes to viewing the movement of humans through walls, there have already been infrared cameras for years, which in most situations will do anything this wifi approach can do and more. The only real advantage of this wifi approach is that it's cheaper, using ubiquitous commodity hardware.

So when it comes to government agencies, this doesn't really change the technological situation: they've already had the ability to track movement through walls for years. They're only restricted in using it to the extent that legal restraints are successful. For example in Kyllo v. United States [wikipedia.org] the Supreme Court threw out a conviction that was obtained in part by using infrared cameras to look inside a home without a warrant.

Re:Code source or it didn't happen

[kk49]

Ya :( This was better http://hackaday.com/2012/12/18/build-a-360-synthetic-aperture-radar-with-mits-opencourseware/ [hackaday.com]

Re:Code source or it didn't happen

[wagnerrp]

While it's nice projects like this open up such technologies to hobbyists, the article is documenting something very novel. Traditional RADAR has trouble seeing through walls, as it cannot filter out all the noise from the wall's reflection. By sending two specially encoded signals that cancel each other out against stationary objects, they've sidestepped this issue entirely, and come up with something brand new. They've developed the much wanted Sci-Fi trope of a portable motion detector.