The arrays used were ULA (Uniform Linear Array), formed by acoustic sensors distributed uniformly along a line. The authors of this paper have experience in the design and development of acoustic arrays used in many different fields, such as detection and tracking systems, ambient assisted living, or biometric identification systems. By using beamforming techniques, the array beam pattern can be electronically steered to different spatial positions, allowing the discrimination of acoustic sources based on their position. Microphone arrays are a particular case, used in applications such as speech processing, echo cancellation, localization, and sound sources separation. The beam pattern of the array can be controlled by modifying the geometry of the array (linear, planar, etc.), the sensor spacing and the beam pattern, the amplitude, and phase excitation of each sensor. IntroductionĪn array is an arranged set of identical sensors, fed in a specific manner. The obtained results reveal the feasibility of the proposed system to obtained acoustic images of a fan matrix and of its individual fans, in this last case, in order to estimate the real position of the fan inside the matrix.
The analysis of the acoustic signals spectra reveals the resonance frequency of the individual fans. The nonstationary signals received by each MEMS microphone and their corresponding spectra have been analyzed, as well as the corresponding acoustic images.
Some tests to obtain the acoustic images of the individual fans and of the whole matrix have been defined and have been carried out inside an anechoic chamber. A matrix of PC fans has been implemented to perform the study. This paper proposes the use of a signal acquisition and processing system based on an planar array of MEMS (Microelectromechanical Systems) microphones to obtain acoustic images of a fan matrix.
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