TL;DR
QuadRF is an open source radio frequency (RF) camera that enables users to visualize Wi-Fi signals and other wireless transmissions in real-time. It combines a complete 4×4 multiple-input multiple-output (MIMO) software-defined radio system with a phased-array antenna and a Raspberry Pi 5, all running open source software. This setup allows hobbyists and educators to see the physical locations of wireless transmitters, such as Wi-Fi access points and drones, displayed as augmented reality overlays on smartphones or laptops.