Calibration system for multi-sensor acoustical systems

In recent years, themulti acoustic sensors systems have had amajor development thanks to their versatility in different fields. These systems, also called acoustic antennas, consist of a set of microphones distributed according to linear, planar or three-dimensional geometries. The acoustic signals detected by the microphones are processed in order to define the location of an acoustic source. The acoustic antennas find large applications in different fields. In automotive they are used to highlight the noise propagation path; in the multimedia, these sensors allow localizing a speaker without portable microphones. Also the civil safety and military fields benefit from these systems: gunshots detection in city areas, fire prevention inwooded zones (Blaabjerg et al. in IV International Conference on Forest Fire Research, 2010), soldiers protection from enemy attacks are just some possible applications (ShotSpotter Gunshot Location System® (GLS). http://www.shotspotter.com). Even in the aerospace field, there are interesting applications such as the monitoring of the air traffic zones (ATZ), locating a plane and tracing its trajectory (Quaranta et al. in ESAV2011-Tyrrhenian InternationalWorkshop on Digital Communications- Enhanced Surveillance of Aircraft and Vehicles, 2011 and Petrella et al. in ICSV19, 2012). The identification of the position of the source requires the knowledge of right acoustic locations of the microphones in the array, generally different from the geometric locations, to this scope a suitable calibration procedure. The proposed method was tuned in a simulation environment to predict signal produced by each microphone. An optimization process was adopted to identify layout configuration guaranteeing the right calibration. The proposed solution was experimentally validated on a two-dimensional acoustic antenna.