Bottom Reverberation in Shallow Water: Coherent Properties as a Function of Bandwidth, Waveguide Characteristics and Scatterer Distributions
Abstract
Shallow water presents a difficult environment for finding submarines. Since shallow water is typically a reverberation limited environment, it is important to understand the predictable structure of the reverberation in order to aid the design of processors and detectors which work properly in these environments. In this report, the temporal characteristics of monostatic reverberation are predicted as a function of source bandwidth, source-receiver depth, and the propagation characteristics of shallow water. Results show that at early time, reverberation can be highly coherent across a vertical line array, violating the homogeneous noise assumption, while at late time the reverberation becomes increasingly uncorrelated. This is shown to be due to the ensonification of independent bottom patches at late time. It is also shown that this decorrelation of the reverberation is dependent on the propagation characteristics of the particular shallow water environment, the correlation length scale of the scatterers, and the bandwidth of the source, with high bandwidth sources causing decorrelated reverberation sooner than low bandwidth sources. The results also show that there are several identifying characteristics in reverberation time series which may be useful for identifying the types of scatterers which cause reverberation during particular experiments. Finally, the techniques developed in this report may be used to generate reverberation time series from scatterers obeying different amplitude and spatial distributions. This ability should be used in the future to help understand whether it is possible to simulate the conditions under which reverberation becomes non-Rayleigh, as has been observed experimentally by the Centre in recent experiments.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2006
- Accession Number
- AD1113091
Entities
People
- Kevin D. LePage
Organizations
- SACLANT ASW Research Centre