title: An active acoustic tripwire for simultaneous detection and localization of multiple underwater intruders.
abstract: An algorithm allowing simultaneous detection and localization of multiple submerged targets crossing an acoustic tripwire based on forward scattering is described and then evaluated based upon data collected at sea. This paper quantifies the agreement between the theoretical performance and the results obtained from processing data gathered at sea for crossings at several depths and ranges. Targets crossing the acoustic field produce shadows on each side of the barrier, for specific sensors and for specific acoustic paths. In post-processing, a model is invoked to associate expected paths with the observed shadows. This process allows triangulation of the target's position inside the acoustic field. Precise localization is achieved by taking advantage of the multipath propagation structure of the received signal, together with the diversity of the source and receiver locations. Environmental robustness is demonstrated using simulations and can be explained by the use of an array of sources spatially distributed through the water column.
authors.affiliation: NATO Undersea Research Centre, Viale San Bartolomeo 400, 19126 La Spezia, Italy. folegot@nurc.nato.int
authors.forename: Thomas
authors.initials: T
authors.lastname: Folegot
authors.forename: Giovanna
authors.initials: G
authors.lastname: Martinelli
authors.forename: Piero
authors.initials: P
authors.lastname: Guerrini
authors.forename: J Mark
authors.initials: JM
authors.lastname: Stevenson
mesh_terms: D000162:Acoustics; D000465:Algorithms; D003198:Computer Simulation; D004777:Environment; D009792:Oceans and Seas; D012623:Seawater; D013017:Sound Localization; D014465:Ultrasonics