Joint sound source localisation of drones and other background sources

It remains a challenge to acoustically localise drones, especially when there are multiple sound sources in the environment. The aim of this paper is to propose and validate an approach for joint acoustic localisation of drones and other background sources using microphone array measurements. This approach consists of a frequency-domain beamforming step, where a discrete number of frequencies in the range of 140 to 1200 Hz are beamformed individually. The location of the maximum output is identified and plotted in the azimuth and elevation direction per frequency and time step. The next step is to extract and separate the trajectories from this plot. The validation shows the correctness of this approach, together with the remaining challenges. Although sources are extracted and separated correctly, overlapping sources are sometimes considered as only one source. Moreover, in low-level drone noise or high-level background noise measurements, erroneous sound sources are identified. Nevertheless, the results show that drones can be localised over long distances, up to 712 m and 593 m for a quadcopter drone in azimuth and elevation direction respectively, and 317 m and 305 m for a fixed-wing drone in azimuth and elevation direction respectively.