Spying Made Simple: Wi-Fi Signals Used to See Through Walls

By Eliza Strickland
Oct 2, 2009 10:08 PMNov 20, 2019 2:57 AM


Sign up for our email newsletter for the latest science news

Looking for an easy, cheap way to spy on your neighbors? Researchers are working on a device that may be just the thing, which uses a simple wireless network to "see" through a wall and detect people moving around in the room beyond. But paranoid apartment-dwellers will be glad to know that the system still has plenty of limitations. At the moment the system can only track movement within a three-foot range, and it can only sense motion--it can't put together a picture of what or who's moving. The system relies on the variations of radio signals in a wireless network.

The signal strength at any point in a network is the sum of all the paths the radio waves can take to get to the receiver. Any change in the volume of space through which the signals pass, for example caused by the movement of a person, makes the signal strength vary. So by "interrogating" this volume of space with many signals, picked up by multiple receivers, it is possible to build up a picture of the movement within it [Technology Review].

The paper describing the technology has been posted on the arXiv pre-print server, and has not yet been peer-reviewed. The device could be more than a boon for voyeurs or robbers. The researchers argue that

the technology could be used in search and rescue operations, with emergency teams using the same radio technology used by Wi-Fi networks to build a web of sensors around a disaster site, revealing the location of victims and survivors [Telegraph].

Related Content: Science Not Fiction: Knight Rider: Seeing Through Walls With Infrared Glasses? 80beats: Light-Bending Scientists Take a Step Closer to InvisibilityImage: Joey Wilson and Neal Patwari

1 free article left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

1 free articleSubscribe
Discover Magazine Logo
Want more?

Keep reading for as low as $1.99!


Already a subscriber?

Register or Log In

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Our List

Sign up for our weekly science updates.

To The Magazine

Save up to 40% off the cover price when you subscribe to Discover magazine.

Copyright © 2024 Kalmbach Media Co.