Acoustic sources analysis using a virtual array based on MEMS microphones

Abstract

The use of arrays with digital MEMS microphones and FPGA-based acquisition/processing sys-tems allows building systems with hundreds of sensors at a reduced cost. This work analyses the performance of a virtual array with 1600 MEMS (40 x 40) microphones. The system is com-posed by a 2D positioning system that places a physical array of 64 microphones (8 x 8) in a grid with 5x5 positions, obtaining a spatial aperture of 1x1 meters. The measured beampattern is compared with the theoretical one for several frequencies and pointing angles. The beampattern of the physical array is also estimated for each one of the 64 positions used by the positioning system. Also, the measured beampattern and the focusing capacity are analysed, since beam-forming algorithms assume spherical wave due to the large dimensions of the array. Finally, frequency and spatial responses for a set of different acoustic sources are obtained showing an-gular resolutions of the order of tenths of degree.