Toshiaki Nakamura
Toshio Tsuchiya
Iwao Nakano
Toshiyuki Nakanishi
Japan Marine Sci. and Technol. Ctr., 2-15 Natsushima-cho, Yokosuka 237, Japan
Ieharu Kaihou
Akio Kaya
Oki Electric Industry Co., Ltd., 688 Ozuwa, Numazu 410, Japan
Toshiaki Kikuchi
National Defence Academy of Japan, 1-10 Hashirimizu, Yokosuka 239, Japan
A 200-Hz low-frequency sound source for ocean acoustic tomography was
developed by using a supermagnetostrictive material made of the rare-earth
metal (Tb, Dy)Fe[sub 2] aimed at increasing the transmission level and the
reduction of the sound source size. A sound-pressure level above 190 dB (re: 1
(mu)Pa at 1 m) with a frequency bandwidth of over 50 Hz were obtained in the
depth range between 800 and 1200 m. Field tests for the long-range propagation
of several hundreds of kilometers were carried out near the Japan Trench in
November 1993. The sound source was moored at a depth of 1242 m and the
hydrophone array was moored at a depth of