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News Link • Surveillance

Radio eyes peer through walls and darkness

• Russia Today

The technique, called radio tomographic imaging (RTI), uses an array of wireless radio transceivers placed around the zone of interest. They both transmit and receive weak radio signals. By analyzing variations in the strength of the signals, a computer program generates a bird’s-eye image with movement of large objects like people displayed in real time. The approach is similar to medical computed tomography, where a program analyzes series of X-ray scans to generate an image of internal organs.



Joey Wilson and Neal Patwari from University of Utah tested RTI with networks of twenty-eight to thirty-four inexpensive transceivers placed on plastic tube poles. The transceivers used were those used in Zigbee networks, which link together home thermostats and other home or factory automation. The system was successfully tested indoors and outdoors as well as through walls.

The researchers have two studies of their method prepared, one due to be published in IEEE Transactions on Mobile Computing journal and another one available at the preprint website

Patwari and Wilson see several applications of their RTI method: "By showing the locations of people within a building during hostage situations, fires or other emergencies, radio tomography can help law enforcement and emergency responders to know where they should focus their attention," they wrote in one of the studies of the method.

It can be also used in marketing to test how good ads are at attracting people’s attention, for home security alarms, for border protection, or to monitor elderly people in their homes. RTI can work where video cameras won’t, like in darkness or in fog

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