Radio signals are versatile phenomena, they even have good reputation in the spying industry, which may seem like a popularity disadvantage, but now it can change for the better. By using WiFi signals, it is also detectable, whether we are alive or not, at least according to Peking University’s researchers, who found a sensing method which maps a certain space, like we all saw it in Prometheus.
Basically you can imagine a detailed and high resolution 3D image drawn by electromagnetic waves about any given confined space. Now, it’s easy to imagine, if you are in that space, let’s just say it’s your bedroom, your tiniest movements can be traced, tracked, analyzed, and interpreted as breast expansion, or lack of it, which means, you’re pretty much gone.
Dan Wu and his colleagues explain the thing even more deeply:
“Fresnel zones refer to the series of concentric ellipsoids of alternating strength that are caused by a light or radio wave following multiple paths as it propagates in free space, resulting in constructive and destructive interference as the different-length paths go in and out of phase.” Any area of space can be braked down into an infinite number of Fresnel zones.
“We conducted indoor experiments with a pair of Wi-Fi transceivers and a metal cup to verify the Fresnel zones’ existence and to show that the received signal varies as expected when an object moves across the zones,” said Wu.
The consequences can be dramatic, as Wu puts it: “In the shorter term, we envision the proposed theory accelerating the nonintrusive human-sensing field, enabling a wide spectrum of new applications in homes, offices, hospitals, warehouses, and more. In the longer term, we believe that synergizing communication and sensing capabilities in computing devices will fuel a revolution in both Internet of Things (IoT) and context-aware computing.”
Of course other Universities and teams also work on this issue, and they also share their results.