David Kirkpatrick

October 2, 2009

Surveillance and wireless data networks

Filed under: Technology — Tags: , , , , , — David Kirkpatrick @ 12:04 pm

This is a pretty ingenious use of wireless data networks. And a pretty cheap method of imaging into rooms and buildings.

From the link:

Researchers at the University of Utah say that the way radio signals vary in a wireless network can reveal the movement of people behind closed doors. Joey Wilson and Neal Patwari have developed a technique called variance-based radio tomographic imaging that processes the signals to reveal signs of movement. They’ve even tested the idea with a 34-node wireless network using the IEEE 802.15.4 wireless protocol, the protocol for personal area networks employed by home automation services such as ZigBee.

The basic idea is straightforward. 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.

The physics arXiv blog post did offer a bit of a caveat:

How might such cheap and easy-to-configure monitoring networks be used if they become widely available? What’s to stop next door’s teenage brats from monitoring your every move, or house thieves choosing their targets on the basis that nobody is inside?

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