Resolution dependence of rough surface scattering using a power law roughness spectrum
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Authors
Olson, Derek R.
Lyons, Anthony P.
Subjects
Advisors
Date of Issue
2021-06-11
Date
Publisher
ArXiv
Language
Abstract
Contemporary high-resolution sonar systems use broadband pulses and long arrays to achieve high resolution. It is important to understand effects that high-resolution sonar systems might have on quantitative measures of the scattered field due to the seafloor. A quantity called the broadband scattering cross section is defined, appropriate for high-resolution measurements. The dependence of the broadband scattering cross section, σbb and the scintillation index, SI on resolution was investigated for one-dimensional rough surfaces with power-law spectra and backscattering geometries. Using integral equations and Fourier synthesis, no resolution dependence of σbb was found. The incoherently-averaged frequency-domain scattering cross section has negligible bandwidth dependence. SI increases as resolution increases, grazing angle decreases, and spectral strength increases. This trend is confirmed for center frequencies of 100 kHz and 10 kHz, as well as for power-law spectral exponents of 1.5, 2, and 2.5. The hypothesis that local tilting at the scale of the acoustic resolution is responsible for intensity fluctuations was examined using a representative model for the effect of slopes (inspired by the composite roughness approximation). It was found that slopes are responsible in part for the fluctuations, but other effects, such as multiple scattering and shadowing may also play a role.
Type
Preprint
Description
The article of record as published may be found at https://doi.org/10.1121/10.0002974
Series/Report No
Department
Oceanography
Organization
Identifiers
NPS Report Number
Sponsors
US Office of Naval Research
Funding
N00014-13-1-0056
N00014-18-WX-00769
N00014-19-WX-00427
N00014-16-1-2268
N00014-18-WX-00769
N00014-19-WX-00427
N00014-16-1-2268
Format
22 p.
Citation
Olson, Derek R., and Anthony P. Lyons. "Resolution dependence of rough surface scattering using a power law roughness spectrum." The Journal of the Acoustical Society of America (2021): 1-22.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.