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1 Nov, 2015 18:45

Wallhack! New see-through-wall scanner perfect for firefighters, smart homes… and the NSA?

Wallhack! New see-through-wall scanner perfect for firefighters, smart homes… and the NSA?

MIT scientists are putting the finishing touches on a technology that will allow those with a small, portable scanner to trace movements of people on the other side of a wall in real time, using the same radio frequency wavelengths as Wi-Fi modems.

Known as RF Capture, the scanner – which in the latest presentation video is a tangle of wires, not a consumer device - emits a signal that is 1/10,000 as powerful as that used by a cell phone. The radio frequency waves bounce off a person on the other side of the wall repeatedly, producing a series of still silhouettes that are then put together to produce a real-time moving image.

“It doesn’t just tell you that there is a person, but tells you the size and the trajectory of the person,” Dina Katabi, who heads the Wireless@MIT research center, told RT from Boston.

The accuracy is astonishing. In a room of 15 people the device knows which specific person is moving 90 percent of the times. The movements themselves are rendered with fidelity – with even gestures of less than an inch being detected by the waves.

“It’s very safe to be exposed to it, even all the time. It also give you the breathing and the heart rate – and other vital signs,” says Katabi, who also notes that the person being watched doesn’t need to wear a receiving device to be captured by the scanner.

All the current alternatives are inferior: thermal imagining doesn’t penetrate walls, X-rays are dangerous and bulky, and Terahertz scanners are much further away from coming onto the market.


Katabi, a Syrian-born engineer who has become one of the rising stars at the Massachusetts Institute of Technology after moving to the US in the 1990s, has been working on the project since 2012, and in August presented what will likely be the first commercial device based on RF Capture to Barack Obama at the White House.

Called Emerald, it will monitor the heart rate, posture and movement of older people, to prevent accidents and call emergency quickly if anything goes awry, and for Katabi this is the first of many potential applications.

“In healthcare, old people live alone and they fall, and you want to be able to detect falls, and other health problems. With firefighters, you wouldn’t send them inside a burning building without seeing if there is anyone in there. In an ordinary home, the scanner would know when I have woken up, and gone to the shower, and adjusted the temperature in each room accordingly,” says Katabi.

But less benign possibilities also seem obvious.

Soldiers would know behind which walls their enemies are hiding, even if they can’t see them, a practice that currently only exists as a cheat in video games, known as wallhacking. Security forces would also be able to monitor the goings-on in a private space without having to obtain a search warrant, and with no knowledge of those inside (and that is before considering the possibility of terrorists, hackers or burglars getting their hands on a wi-fi scanner).

“We are targeting more applications in the healthcare and smart home sphere, than law enforcement,” says Katabi curtly.

While Katabi is aware that the unprecedented powers of Wi-Fi scanners will raise a host of ethical, legal and practical issues, she believes that dystopian fears rarely play out in real life.

“When technology introduced cameras in our cell phones everybody was very worried that it would start taking illicit pictures in bathrooms or locker rooms,” she remembers with a laugh.


And in any case, she says the boundaries for where the technology should and shouldn’t be used is set by lawmakers and customers, and not engineers.

“With any technology there are good and bad applications. For customers, it will be possible to block this technology if someone doesn’t want to be monitored, and also society needs to develop policies and rules that would prevent people from abusing this technology.”