Spectral broadening of acoustic tones generated by unmanned aerial vehicles in a turbulent atmosphere

Vladimir E. Ostashev, D. K. Wilson, Anthony Finn, Kevin Rogers, Emre Barlas

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The acoustic spectrum emitted by unmanned aerial vehicles (UAVs) and other aircraft can be distorted by propagation through atmospheric turbulence. Since most UAVs are propeller-based, they generate a series of acoustic tones and harmonics. In this paper, spectral broadening of these tones due to atmospheric turbulence is studied. The broadening results from the combined Doppler effect of multiply scattered acoustic signals propagating in a non-stationary turbulent atmosphere. It can be assessed as a Fourier transform of the temporal coherence function of a monochromatic signal propagating in an atmosphere with spatial-temporal fluctuations in temperature and wind velocity. This temporal coherence was recently investigated [V. E. Ostashev, D. K. Wilson, S. N. Vecherin, and S. L. Collier, J. Acoust. Soc. Am. 136 (5), 2414–2431 (2014)] for the model of locally frozen turbulence. Based on these results, spectral broadening is calculated and analyzed for typical meteorological regimes of the atmospheric boundary layer and different flight trajectories of UAVs. Experimental results are presented and compared with theoretical predictions. Spectral broadening might also provide a means for remotely sensing atmospheric turbulence. © 2016 Acoustical Society of America
Original languageEnglish
JournalAcoustical Society of America. Journal
Volume140
Issue number4
Pages (from-to)3119-3119
Number of pages1
ISSN0001-4966
DOIs
Publication statusPublished - 2016

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