P017

Scattering of low Frequency Sound in East China Experiment

A0040 Masamichi Oikawa 5th Research Center, Technical Research and Development Institute, Japan Defense Agency

A0037 Kazuhiko Ohta 5th Research Center, Technical Research and Development Institute, Japan Defense Agency

A0038 Kouki Okabe 5th Research Center, Technical Research and Development Institute, Japan Defense Agency

A0041 Shigeru Suzuki 5th Research Center, Technical Research and Development Institute, Japan Defense Agency

A0042 Itaru Morishita Oki Electric Industry Co., Ltd

A0043 Hisayuki Kanda Oki Electric Industry Co., Ltd

A0044 Hirotaka Murakami Oki Electric Industry Co., Ltd

A0045 Hideo Kano Oki Electric Industry Co., Ltd

A0046 Kenichi Machida Oki Electric Industry Co., Ltd

As active sonar extends the sound frequency to a lower region, the reverberation

feature corresponding to the frequency in use has to be understood to operate

the sonar effectively. Especially in shallow water, the characteristic of sound scattering

from the seabed affects significantly the capability of active sonar. To study this,

an experiment was conducted in the continental shelf of East China Sea by using

a flextentional-type transducer, which can cover a frequency less than 1kHz, and

a vertical line array comprised of 28 sensors. Both of them were suspended vertically

from a ship, the engine of which was shut down to reduce the ship noise.

The array is also equipped with tilt, depth and directional sensors to continuously monitor

the beam direction, which was subject to movement due to the variation of a sea current.

The surface and bottom scattering parameters provided in model were derived with use of

stochastic inversion processing based on perturbation method repeatedly. The scattering

calculated using these parameters is demonstrated to make a considerably good agreement

with the measured one.