Wi-Fi signals used to see through walls

"Researchers from the University of Utah have found a way of harnessing Wi-Fi signals to see through walls.
The researchers say that the variation of radio signals in a wireless network can reveal the movements of people behind closed doors or even a wall.

Joey Wilson and Neal Patwari, from the University of Utah, have used the principle of variance-based radio tomographic imaging. The system works by measuring interference between the nodes of wireless devices. If someone passes through that field, the device registers a change in the levels of resistance, and feeds that information back to a computer."

-Telegrah.co.uk

-arXiv.org