Wi-Fi detection system sees through walls

Developed by a team at University College London, the technology is similar in principle to traditional radar, but rather than actively transmitting radio waves, it makes use of the “soup” of Wi-Fi signals that already swamp our airwaves.

Dr Bo Tan, one of the lead researchers on the project, told The Engineer that the technology has potential applications in a range of scenarios, from surveillance of hostage situations to gesture recognition systems. The system could also be used to monitor people in their homes and trigger an alert if they fall, he said.

Tan explained that like traditional radar systems, the technology relies on detecting Doppler shifts in radio waves as they reflect off moving objects.

He said that in order to capture target movement the technology requires at least two receiver channels. One channel locks onto a direct base radio signal from a local wireless signal transmitter (such as a router) whilst the other measures the reference signal as it bounces off a moving target.