This research is based on the analysis and interpretation  of data originally collected by DREP. Currently there are two graduate student  projects. The first project makes use of DREP data from the PACIFIC SHELF sea trial  carried out in Sept 93 (Fawcett et al, 1996). The goal of the project is to take  advantage of the complexity of the environment, in this case the bathymetry of a  continental slope, to localize a source in range, depth and bearing with a vertical  line array (VLA) using matched field processing. In the absence of the sloping bottom,  it would not be possible to localize in bearing with a VLA due to the cylindrical  symmetry of the problem; in effect, the slope breaks the symmetry. This work was the  MSc thesis project of Lt(N) M. Taillefer (June 98). Mr. Taillefer implemented an  adiabatic normal mode method to generate replica fields for use in the matched field  processing, and processed a set of data from PACIFIC SHELF in which a source was  towed over the slope. His work demonstrated the effect of environmental symmetry  breaking: the source can be located and tracked in range, depth and bearing, and  furthermore, it appears that there is no detrimental effect due to three-dimensional  sound propagation on the slope at the short range (5.5 km) of the experiment.

Matched Field Inversion using Broadband Ship Noise (R. Chapman and R. Dizaji)

     The concept of using radiated broadband noise from  ships as a sound source for MF inversion was investigated by R. Dizaji in his PhD  thesis. The project was supported by an NSERC research partnership program with  DND and industry (MacDonald-Dettwiler). Mr. Dizaji developed a novel broadband  processor for random signals based on the cross-relation property of the signals  at pairs of hydrophones on a vertical array. The processor is robust to mismatch,  similar to the conventional Bartlett MF processor, and displays the high resolution  property of the minimum variance MF processor. The performance of the cross-relation  processor was superior to that for any of the conventional processors. Higher order  formulations were also generated to investigate the information in higher order  statistics of the ship noise signal. The method was demonstrated for both source  localization and inversion using experimental data from PACIFIC SHELF. The figure  shows the matched field ambiguity surface for the cross-relation processor that was  generated using radiated ship noise. The location of a surface ship and a towed  sound source is well resolved.