The basic principle of finding the direction of a radio signal is actually very simple to understand. The system measures the phase difference between different antennas on the device. Based on this difference, the exact angle of arrival of the signal is calculated. However, the necessary hardware has been difficult to access for enthusiasts until now. That’s why it’s the QuadRF team.
A new project called QuadRF he wants to change it completely, and the first presentation of it has been made.
Hardver connection with mini Raspberry Pi 5 computer
The QuadRF system uses two separate electronic boards for successful operation. The first plate serves for the reception and initial processing of radio waves. A popular computer is used for additional data processing Raspberry Pi 5.
The main board has four special high-performance antennas. They can send and receive signals in the range of 4.9 to 6 GHz. The hardware also supports changing the left or right wave polarization.
It is responsible for fast data processing on the device itself Lattice ECP5 FPGA chip, which connects to the computer via two high-speed MIPI cables. This creates an extremely fast connection for the exchange of all data.
After processing, the mini computer sends the data via an Ethernet network or a Wi-Fi connection. Also, multiple QuadRF boards can be connected in a large mesh array, thus easily forming advanced antenna systems.
The software creates a camera for radio signals
The real strength of this open source project lies in its software. The device is fully compatible with the standard program GNU Radio. However, the authors have developed their own very interesting applications. The most attractive function is the so-called special function Camera RF. It scans the entire frequency range at a speed of 30 frames per second, follows the direction of the detected signals and displays them graphically.
The data can be successfully superimposed over a classic video recording, which allows users to clearly see radio signals from electronics. The creators thus successfully tracked the drone in full flight, and the system accurately distinguished two separate transmitters on the aircraft.
The first system that can also emit signals
This isn’t the first multiple antenna system we’ve seen. However, this is the first affordable model that can also emit signals.
It should be emphasized that users must be very careful when working with this and this kind of hardware. Some applications of this advanced technology are subject to strict arms control regulations and vary around the world, warns Hackaday.