A Student Figured out a Way to See People Through Walls Using Their Wi-Fi

(ANTIMEDIAGerman scientists from the Technical University of Munich have developed technology that uses wi-fi to “see” through walls. Philipp Holl, a 23-year-old undergraduate physics student at the Technical University of Munich, told Business Insider the new device “can basically scan a room with someone’s Wi-Fi transmission.”

Holl developed the concept for technology with the help of his academic supervisor, Friedemann Reinhard, as part of his bachelor thesis. They published their findings in the journal Physical Review Letters.

While wi-fi technology is already being used to construct two-dimensional images and detect home intruders and other moving objects, this goes much further, creating 3-D holograms of the contents of an entire room. According to Holl, “Our method gives you much better images, since we record much more signal. We scan the whole plane of a room.”

To construct the hologram, two antennas are used — one stationary antenna to record the background of the room and another that is moved by hand to scan the wi-fi field from a broad area. “These antennas don’t need to be big. They can be very small, like the ones in a smartphone,” Holl said. Both antennas record the wi-fi signal for intensity and phase and feed the data into a computer where special software uses the information to produce a holographic image of the room.

Holl notes that the technology is still in prototype stage but is enthusiastic about its potential. “If there’s a cup of coffee on a table, you may see something is there, but you couldn’t see the shape,” Holl says. “But you could make out the shape of a person, or a dog on a couch. Really any object that’s more than 4 centimetres in size.”

As it develops, the new wi-fi holography technology is likely to be applied in a number of ways. Holl mentioned the lives it could save by helping rescue workers detect the location of people stuck in buildings after a catastrophe. “You could probably use a drone to map out the inside of an entire building in 20 to 30 seconds,” he said, which, unfortunately, opens the door for those with more sinister motives who may get their hands on the technology.

“Of course, this raises privacy questions. After all, to a certain degree even encrypted signals transmit an image of their surroundings to the outside world,” project leader Friedemann Reinhard said in a press release from TUM. “However, it is rather unlikely that this process will be used for the view into foreign bedrooms in the near future. For that, you would need to go around the building with a large antenna, which would hardly go unnoticed. There are simpler ways available.”

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