The influence of meteorological conditions for the localization of an acoustic source by means of a microphone antenna

In this paper, we study the effect of atmospheric turbulence on sound propagation in the low atmosphere and of its influence on the localization of vehicles. In the course of experiments, the average and fluctuating meteorological magnitudes of the low atmosphere have been measured in order to have a better knowledge of the stability state, and of the rates of thermal and kinematic fluctuations of the atmosphere. The localization antenna is made up of two overlapping linear antennas, each composed of 8 microphones. The whole acoustic and meteorological data have been measured simultaneously and recorded in situ. From this information, an average value analysis has allowed us to layout the vertical speed profiles of the wind and temperature by means of the Monin-Obukhov theory of similarity. In three different cases of wave refraction, these profiles have been used for a model of propagation based on the method of rays in order to calculate the sound paths and for a calculation code of the acoustic level (PE) allowing us to know the propagation conditions of the wave between the source and the antenna. Then the localization results have been analyzed together with thermal and kinematic fluctuation results of the low atmosphere. A narrow relationship between the precision of the localization results and eigenvalues of the correlation matrix of acoustic signals has been established. The degradation of these eigenvalues is a direct consequence of the thermal and the kinematic fluctuation rates of the low atmosphere.