| Summary: | The usage of drones is increasingly spreading into new fields of application, ranging from agriculture to security. One of these new applications is sound recording in areas of difficult access. The challenge that arises when using drones for this purpose is that the sound of the recorded sources must be separated from the noise produced by the drone. The intensity of the noise emitted by the drone depends on several factors such as engine power, propeller rotation speed, or propeller type. Noise reduction is thus one of the greatest challenges for the next generations of unmanned aerial vehicles (UAVs) and unmanned aerial systems (UAS). Even though some advances have been made on that matter, drones still produce a considerable noise. In this article, we approach the problem of removing drone noise from single-channel audio recordings using blind source separation (BSS) techniques, and in particular, the singular spectrum analysis algorithm (SSA). Furthermore, we propose an optimization of this algorithm with a spatial complexity of <inline-formula> <tex-math notation="LaTeX">$\mathcal {O}(nt)$ </tex-math></inline-formula>, which is significantly lower than the naive implementation which has a spatial complexity of <inline-formula> <tex-math notation="LaTeX">$O(tk^{2})$ </tex-math></inline-formula> (where <inline-formula> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> is the number of sounds to be recovered, <inline-formula> <tex-math notation="LaTeX">$t$ </tex-math></inline-formula> is the signal length and <inline-formula> <tex-math notation="LaTeX">$k$ </tex-math></inline-formula> is the window size). The best value for each parameter (window length and number of components used to reconstruct the source) is selected by testing a wide range of values on different noise-sound ratios. Our system can greatly reduce the noise produced by the drone on said recordings. On average, after the recording has been processed by our method, the noise is reduced by 1.41 decibels.
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