See-through-wall surveillance with WiFi shown at UCL

A surveillance device that uses WiFi radio waves has been devised to see through walls to detect, in military and surveillance parlance, moving personnel targets. The device serves as a radar prototype designed by two UK scientists at the University College London (UCL). The scientists devised the radar prototype as a way to track Wi-Fi signals in order to spy through walls. Their device identifies frequency changes to detect the moving objects. An important feature of their work is that since the device itself does not emit radio waves, it cannot be detected; it operates in stealth.