Spectrum monitoring with unmanned aerial vehicle carrying a receiver based on the core technology of cognitive radio – a software-defined radio design

In this paper, we design and make a prototype of an aerial spectrum monitoring system that consists of a ground control station and a four-rotor unmanned aerial vehicle (UAV). This UAV carries a software-defined radio (SDR) receiver to perform spectrum monitoring tasks, including signal strength, frequency occupancy, and signal analysis. A light and low-cost SDR-based dongle consisting of RTL2832U chip and R820T tuner is employed as the monitoring receiver. A global positioning system and an electronic compass system are built on board to report the UAV’s position and direction. The open-source development platform GNU Radio is employed to design the radio monitoring system through the use of software-defined blocks. The proposed aerial monitoring system can detect radio signals in the frequency range of 25–1700 MHz that in practice covers the FM and DVB bands. With the prototype monitoring system, we have performed a few measurement tasks, including signal strength, waterfall display, and demodulation for identifying FM stations. Our proposed aerial monitoring system is more cost-effective than land-vehicle monitoring stations because of its much more flexible implementation.