Acoustic goniometry

This work was motivated by the increasing need for acoustic localization systems. The various localization systems that were implemented during this PhD include localization of snow avalanches, artillery and supersonic aircraft in the infrasound domain, the localization of helicopters, civilian aircraft, speakers and auditorium reflections in the audio domain and the localization of chirps in the underwater ultrasound domain. The "goniometer" is defined as an instrument that measures angles. An "acoustic goniometer" is therefore a system that measures the direction of arrival (DOA) of sounds, and thus estimates the source direction. A goniometer is made up of an antenna, composed of several sensors arranged in a particular geometry, and a calculation algorithm. The successive implementations were designed around a common framework, based on a two-step spatio-temporal process. The temporal step tackles the problem of the Time Delay Estimation along the antenna baselines, whereas the second step introduces the antenna geometry, in order to estimate the Direction of Arrival per se. The multi-sources case, as well as the outlier's rejection, is assured by a detection module, which uses the temporal and spatial properties of the propagation model. The performances of the TDE and the localization are studied as a function of every relevant parameter, in order to determine the optimal antenna to run the two-step process. The antenna design rules concern its geometry, its size and its orientation. The results presented in the applications chapter give a realistic idea of the goniometry capacities. Its performances are largely competitive to those of other techniques. Up to now, the goniometry developed during this work, fulfilled all prior requirements. Moreover, the goniometry appeared to be, in many cases, in advance with regards to technological tools such as the sound pick-up, the CPU implementation or installation constraints. The advice that could be given, when tackling a new antenna design, is firstly to visualize both spatial and temporal properties of the propagating waves and of the perturbating phenomena, and secondly to compare them to the goniometer characteristics. This work has demonstrated that the best performances were achieved for the goniometry of a unique stationary compact source generating broadband low pass signals in a homogenous medium without wind and noise, performed with a wide symmetrical broad-side antenna.