University of Utah engineers showed that a wireless network of radio transmitters can track people moving behind solid walls.

The system could help police, firefighters and others nab intruders, and rescue hostages, fire victims and elderly people who fall in their homes.

"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," Joey Wilson and Neal Patwari wrote in one of two new studies of the method.

Both researchers are in the university's Department of Electrical and Computer Engineering - Patwari as an assistant professor and Wilson as a doctoral student.

Their method uses radio tomographic imaging (RTI), which can "see," locate and track moving people or objects in an area surrounded by inexpensive radio transceivers that send and receive signals. People don't need to wear radio-transmitting ID tags.

One of the studies - which outlines the method and tests it in an indoor atrium and a grassy area with trees - is awaiting publication soon in IEEE Transactions on Mobile Computing, a journal of the Institute of Electrical and Electronics Engineers.

The study involved placing a wireless network of 28 inexpensive radio transceivers - called nodes - around a square-shaped portion of the atrium and a similar part of the lawn. In the atrium, each side of the square was almost 14 feet long and had eight nodes spaced 2 feet apart.

On the lawn, the square was about 21 feet on each side and nodes were 3 feet apart. The transceivers were placed on 4-foot-tall stands made of plastic pipe so they would make measurements at human torso level.

"On the left, a person walks around inside a square of 28 radio transceivers (mounted on plastic pipes) in the Warnock Engineering Building's atrium at the University of Utah. The person creates "shadows" in the radio waves, resulting in the image displayed on right, in which the person appears as a reddish-orange-yellow blob. University of Utah engineers also showed this method can "see" through walls to make blurry images of people moving behind the walls. They hope the technique will help police, firefighters and other emergency responders apprehend burglars and rescue hostages, fire victims and others. (Credit: Sarang Joshi and Joey Wilson, University of Utah)"

Source: University of Utah