Contribution
Analysis of hydroacoustic ship signatures in multipath environments by the cepstrogram
* Presenting author
Abstract:
Due to multipath sound propagation, the analysis of hydroacoustic ship signatures in shallow water is difficult. In deep waters, reflection at the water surface is known to create an interference effect, known as Lloyd mirror effect. In shallow water, additional reflections at the sea bottom create considerably more complicated interference effects. If hydroacoustic recordings are analysed by signal decomposition algorithms, these effects create spurious components that need to be identified. As a tool for this purpose, we propose the cepstrogram, as already used in speechprocessing or seismic signal analysis. The cepstrogram represents a time-resolved version of the classical cepstrum. If an array of hydrophones is available, the detection performance of the cepstrum can be increased by a statistical hypothesis test, similar to the Analysis of Variance (ANOVA). For the situation of a ship passing by a set of hydrophones, located at the sea bottom, we analyse experimental data obtained at a sea trial in shallow waters, and compare the results to simulations.