Want X-ray vision like the man of steel? A technology that lets you see behind walls could soon be built in to your cell phone.
MIT professor Dina Katabi and graduate student Fadel Adib have announced Wi-Vi, a demonstration of a technology that uses Wi-Fi to allow a viewer to "see" a person moving behind a wall. (Wi-Vi stands for "Wi-Fi" and "vision.")
Previous work demonstrated that the subtle reflections of wireless inter signals bouncing off a human could be used to track that person's movements, but those previous experiments either required that a wireless router was already in the room of the person being tracked, or "a whole truck just to carry the radio," said Katabi.
Wi-Vi at work - see video below
The new device uses the same wireless antenna as is found in a cell phone or laptop and could in theory one day be embedded in a phone. [See also "WiSee Detects Your Gestures Using WiFi."]
The trick is cancelling out all interfering signals - Wi-Fi doesn't just bounce off humans, but also walls, floors, and furniture. And those signals are 10,000 to 100,000 times more powerful than the reflections off a human body.
Katabi's Wi-Vi sends out two wireless signals, one of which is the inverse of the other. In what Katabi calls "interference nulling," the two signals cancel each other out unless they hit a moving target - such as a human.
"To silence the noise, we change the structure of the Wi-Fi signal so all the undesired reflections cancel," she said.
The device is meant to be portable so, for example, a person worried that someone was hiding in the bushes could do a quick scan for her personal safety.
Wi-Vi could also serve as a high tech baby monitor or help Superman - or just cops - catch baddies.
See: Research paper by Fadel Adib and Dina Katabi
Video: Wi-Vi: See through Walls with Wi-Fi signals
Video: Wi-Vi: See through Walls with Wi-Fi signals
Top image: Illustration by Christine Daniloff/MIT
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