Extraction of Target Scatterings from Received Transients on Target Detection Trial of Ambient Noise Imaging with Acoustic Lens

• Kazuyoshi Mori

• Hanako Ogasawara

• Toshiaki Nakamura

• Takenobu Tsuchiya

• Nobuyuki Endoh

Abstract

We have already designed and fabricated an aspherical lens with an aperture diameter of 1.0 m to develop a prototype system for ambient noise imaging (ANI). It has also been verified that this acoustic lens realizes a directional resolution, which is a beam width of 1° at the center frequency of 120 kHz over the field of view from -7 to +7°. In this study, a sea trial of silent target detection using the prototype ANI system was conducted under only natural ocean ambient noise at Uchiura Bay, in November of 2010. There were many transients in the received sound. These transients were classified roughly into directly received noises and target scatterings. We proposed a classification method to extract transients of only target scatterings. By analyzing transients extracted as target scatterings, it was verified that the power spectrum density levels of the on-target directions were greater than those of the off-target directions in the higher frequency band over 60 kHz. These results showed that the targets are successfully detected under natural ocean ambient noise, mainly generated by snapping shrimps.

Journal

• Japanese Journal of Applied Physics

  Japanese Journal of Applied Physics 51 (7S), 07GG10-, 2012-07-01

  IOP Publishing

Keywords

• General Physics and Astronomy
• General Engineering

Details

• CRID: 1360566396810501120
• NII Article ID: 210000072633
• DOI: 10.1143/jjap.51.07gg10
• ISSN: 13474065
• ISSN: 00214922
• Web Site: https://iopscience.iop.org/article/10.1143/JJAP.51.07GG10
• Web Site: https://iopscience.iop.org/article/10.1143/JJAP.51.07GG10/pdf
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