The open-source RF imaging platform combines a Raspberry Pi 5, phased-array antennas, and software-defined radio (SDR) technology to visualise and analyse wireless signals in real time.
QuadRF is an open-source RF imaging platform that converts a Raspberry Pi 5 into a real-time RF camera that enables visualisation of the wireless signals around it through augmented reality. The system uses a 4 × 4 MIMO SDR along with a phased array antenna and open-source software to visualise and map wireless transmitters such as Wi-Fi access points, drones, wireless cameras, and beacons.
At the core of QuadRF is a coherent four-antenna array that measures minute arrival time differences between radio signals. This information is used to create a live augmented reality display with up to 30 frames per second, allowing users to identify the location of wireless transmitters rather than only their signal strength. The wireless transmitters are coded with different colours depending on their frequency.
The device also allows users to route the received signals to the SDR software for decoding or to transmit a beamformed signal back towards the device. The Raspberry Pi 5 computer runs the web interface, calibration software, and multiple SDR software locally, while the compute-intensive signal processing can be performed remotely via Gigabit Ethernet, USB 3.0, and Wi-Fi by external software, including GNU Radio, SDRangel, and Pothos.
QuadRF is a system based on a full-duplex 4×4 MIMO design that works in the range from 4.9 GHz to 6.0 GHz in the C-band spectrum. The antennas support up to 40 MHz of instantaneous bandwidth and up to 1 W of transmit power. The signal processing is carried out by the Lattice ECP5 FPGA and Raspberry Pi 5 computers, while the software stack is released under GPL licenses.
As per the developers, the system can be used for studying of beamforming techniques, RF propagation, characterization of antennas, wireless networking, robotics, and software-defined radio development. The developers also envision it as an educational platform for studying phased-array systems, MIMO, and spatial RF concepts without specialised laboratory equipment. Multiple QuadRF modules can be combined into larger phased-array systems.
