Abstract
This paper investigates different approaches in designing an acoustic camera with respect to the shape of the camera as well as the number of microphones and their position on the camera. Micro electro-mechanical systems (MEMS) microphones are used in this research for the purpose of designing an acoustic camera. Several simulations implemented in MATLAB were performed for square MEMS microphone arrays, bearing in mind our primary goal, which is to design a broadband frequency range acoustic camera with MEMS microphones. In addition, a microphone array in the shape of a hemisphere was designed in order to compare all of the obtained results. Results gathered in the simulations have shown that using the square arrays and a hemispherical array enables us to construct four different broadband frequency range acoustic cameras. All of the considered versions of an acoustic camera have a respectable gain in the desired direction (i.e. the gain of the main lobe) and, in addition, a significant attenuation of side lobes. Keeping in mind the aforementioned requirements (i.e. the main lobe gain and attenuation of side lobes) it can be concluded that, from all of the considered designs, the best design is the acoustic camera with 24 MEMS microphone square array.
Highlights
This paper explains the designing process of an acoustic camera with micro electro-mechanical systems (MEMS) microphones [1, 2, 3]
Nowadays different types of MEMS microphones are an important part of modern electronics
Processes used in their production are similar to the processes used in the production of semiconductor integrated circuits. They are implemented in a majority of devices considering their many advantages i.e. small size, relatively good sound quality, reliability and small prices. Keeping in mind their small size and relatively low costs, they are progressively used in acoustic cameras, smartphones and microphone arrays designing [5, 6]
Summary
This paper explains the designing process of an acoustic camera with micro electro-mechanical systems (MEMS) microphones [1, 2, 3]. Required for positioning the microphones in a particular configuration, for square, circular and hemispherical MEMS microphone arrays at frequency 1000 Hz. Array configuration a) Square, 4 microphones b) Square, 16 microphones c) Circular, 8 microphones d) Circular, microphones e) Hemisphere, microphones f) Hemisphere, 25 microphones dmax = 0.1 m 1.21 dBi 5.69 dBi 7.93 dBi 9.09 dBi 1.14 dBi 4.01 dBi. Bearing in mind our primary goal, which is to design a broadband acoustic camera with MEMS microphones, we have optimized the construction of the microphone array so that the gain in the desired direction and the attenuation of side lobes is maximized at a frequency up to 4 kHz. In our previous research [14], several simulations were performed considering square, circular and MEMS arrays in the shape of a hemisphere with varying number of microphones and varying spacing between the microphones. It can be noticed from the results gathered at a broadband frequency range that the best results are obtained using a square microphone array with 16 microphones For this casescenario we wanted to analyze if it is possible to design an acoustic camera with even better performances for a broadband frequency range. We wanted to test a “new” hemispherical array with 17 microphones shown in Figure 3. in order to compare the obtained results with the square shaped microphone arrays
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