Statistics of broadband transmissions through a range-dependent fluctuating ocean waveguide
Poster presented at the 2007 Validating TestBED and Research on Real World Problems for I-PLUS Development Conference
Acoustic signals transmitted through an ocean waveguide are temporally and spatially varying due to multimodal interference and effects such as internal waves. Estimating parameters of sonar, the environment and scatterers requires a statistical approach that incorporates medium uncertainties into the signal analysis. Short duration broadband pulses were transmitted from a moored source array and measured by a towed horizontal receiving array at varying ranges from the source. The ping-to-ping fluctuations in the measured acoustic data are a result of changes in the waveguide modal intereference structure due to both motion of the array and presence of time dependent random internal waves. Our analysis shows that the Parseval sum and match filter outputs of the broadband transmissions for the direct arrival have significantly smaller standard deviations compared to the instantaneous single frequency transmission. We account for these observations by modeling the broadband acoustic field intensity in both a static waveguide and with Monte Carlo simulations in a fluctuating waveguide. A maximum likelihood estimator is implemented to provide a global inversion of the data for source level and a range-dependent expected intensity, as well as quantifying the match filter degradation in the multi-modal ocean waveguide.
Mark Andrews, Purnima Ratilal, Tianrun Chen, Sunwoong Lee, and Nicolas Makris. "Statistics of broadband transmissions through a range-dependent fluctuating ocean waveguide" SeaBED Presentations.. Jan. 2007.
Available at: http://works.bepress.com/pratilal/2