See Through Walls Using a Wireless Network

http://www.sporkings.com/2009/10/see-through-walls-using-a-wireless-network/

It is quite simple, frankly! Radio signals are sent and received in a wireless network. These signals vary in a predictable way when the volume of space in which they travel changes. Why would the volume of space change? Well, any movement will have this effect regardless if it is a bird, an object, or a person that is moving. Although it is at the beginning, this technology has potential for huge breakthroughs.

“We envision a building imaging scenario similar to the following. Emergency responders, military forces, or police arrive at a scene where entry into a building is potentially dangerous. They deploy radio sensors around (and potentially on top of) the building area, either by throwing or launching them, or dropping them while moving around the building. The nodes immediately form a network and self-localize, perhaps using information about the size and shape of the building from a database (eg Google maps) and some known-location coordinates (eg using GPS). Then, nodes begin to transmit, making signal strength measurements on links which cross the building or area of interest. The received signal strength measurements of each link are transmitted back to a base station and used to estimate the positions of moving people and objects within the building.”

[Source: www.sporkings.com]