10 years ago a guy did WiFi signal mapping using a single antenna and a CNC router. https://www.youtube.com/watch?v=aqqEYz38ens
This real time visualization is pretty mind-blowing. Filter by MAC address? Wonder how long this has been used by the usual suspects.
Reminds me of the faraday cage in 'The Conversation'.
Filter by MAC address?
I didn't even catch that detail. That's wild. Filter everything that's not your subject. This doesn't even need to do other RF because anything RF these days has Wi-Fi (or cellular).