Tommy G. Goldsberry
Office of Naval Res., 800 N. Quincy St., Arlington, VA 22217-5660
Joseph M. Monti
Michael Werbicki
Naval Undersea Warfare Ctr., Newport Div./Detachment New London, New London, CT 06320-5594
A unique tool for low/mid-frequency (LF/MF) shallow-water reverberation and scattering measurements has been developed. The towed vertically directive source (TVDS) is designed to overcome the two critical deficiencies in most attempts to measure LF scattering characteristics of the ocean bottom in shallow water---insufficient source level and inadequate directivity of the sound source. Although TVDS provides high source level and directivity at LF and MF (220 to 230 dB over the frequency band from 400 to 4000 Hz) it is designed for use on 3000 ton research vessels at tow depths to 180 m. An articulated strut allows aperture for a 20 deg vertical beamwidth at 600 Hz but permits TVDS to be deployed and retrieved with the low-frequency array retracted. An MF array with center frequency of 3000 Hz is mounted in the vertical stabilizer of TVDS and also provides a 20 deg vertical beamwidth. Provision for simultaneous transmission at LF and MF will permit frequency diversity in measurements over a decade of frequency with scattered signal reception on the TVDS transducer arrays or an adjunct towed array. TVDS design and test results will be discussed. [Work sponsored by ONR.]