Tuesday 11 February 2020 16:00 – 17:00 A. Payatakes Seminar Room
“Localization of Sperm Whales with a 3-Hydrophone Array”
Dr Despoina Pavlidi Institute of Applied and Computational Mathematics
Abstract
Passive acoustic monitoring of marine mammals involves the use of hydrophones to localize vocalizing animals by merely listening to them and not disturbing them in any way. Sperm whales produce trains of pulsed sounds, so called clicks, during their long dives to depths of 1000 m or more. These sounds serve for communication and foraging (biosonar) and if they are picked up by a hydrophone array they can be used for animal localization and study. The focus here is on localization, which, apart from monitoring, can help the design of mitigation protocols to protect endangered populations from human activities. An underwater localization method based on +me-differences of arrival at 3 hydrophones will be presented. This is an extension to a previously proposed algorithm using 2 hydrophones and aims at the removal of pitfalls observed in the 2-hydrophone localization. Refraction of acous+c paths in the underwater environment is taken into account using ray theory. Further, a Bayesian framework is adopted allowing for the estimation of localization uncertainties. Three different array topologies are studied and their performance is compared against the 2hydrophone topology. The improvements obtained by the 3-hydrophone localization approach, in terms of removal of left-right ambiguity in azimuth estimation and reduction of uncertainty in broadside range estimation, will be highlighted.