Wi-Fi can detect movement through walls

Summary:Researchers at University College London have created a device that can detect objects through a wall by measuring the Doppler effect.

Wi-Fi has opened up many doors to the world in terms of how we stay connected. And now Wi-Fi can see right through those doors and walls (at least ones that are one-foot thick) to detect moving objects or people on the other side.

A team of electrical engineers at University College London has developed a device that uses radio signals from Wi-Fi to detect movement through walls. The device can detect movement by measuring the Doppler effect -- the change in radio wave frequency caused by the presence of a moving object.

The device is as big as a suitcase and uses two antennas -- one to track the base radio signal in an area where a router is set up and another to detect radio waves that have reflected off of a moving object. Once captured, the information gets sent to a computer for analysis.

Discovery News reports:

"The device reads these frequency changes and calculates not only when an object is moving, but also its speed, location and the direction it’s going. For example, if a person is moving toward the Wi-Fi source, the frequency of waves increases; if a person is moving away from the source, the frequency of the waves decreases."

Wi-Fi is so ubiquitous today that a device like this could have many uses from identifying humans behind walls in search and rescue missions to scanning a building during a hostage situation.

And the device does not give off any of its own radio signals so it can't be detected.

Researchers are now working on ways to improve the device "to include the ability to pick up subtle movements like the rise and fall of one’s chest when breathing, in order to sense someone even if they are standing still," Discovery News reports.

via Discovery News

Photo via flickr/jessica mullen

This post was originally published on Smartplanet.com

Topics: Innovation


Contributing Editor Amy Kraft is a freelance writer based in New York. She has written for New Scientist and DNAinfo and has produced podcasts for Scientific American's 60-Second-Science. She holds degrees from CUNY Graduate School of Journalism and the University of Illinois at Chicago. Follow her on Twitter. Full Bio

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