I remember something similar from years ago but this is more recent: https://www.zmescience.com/feature-post/technology-articles/computer-science/wifi-router-se

I remember something similar from years ago but this is more recent: https://www.zmescience.com/feature-post/technology-articles/computer-science/wifi-router-sees-people-through-walls/ https://www.zmescience.com/feature-post/technology-articles/... > For their demonstration, the researchers used three $30 WiFi routers and three aligned receivers that bounce WiFI signals around the walls of a room. The system cancels out static objects and focuses on the signals reflected off moving objects, reconstructing the pose of a person in a radar-like image. This was shown to work even if there was a wall between the routers and the subjects.