DEEP WATER ACOUSTIC SOURCE

Description

High Tech, Inc.'s Deep Water Acoustic Source is characterized by wide bandwidth, high output, exceptional reliability, and full ocean depth capability. The Naval Research Laboratory has operated one of these sources for over 10 years. The Deep Water Acoustic Source is a Helmholtz resonator type transducer with output from 250 Hz through 900 Hz at 201 dB re: 1µPa @ 1 m. Output can be a swept chirp or a pulsed constant frequency, capable of achieving spatial resolution on the order of 5 meters. This source will operate in water depths up to 6000 meters.

image: Photo of source

The output waveform is calibrated and highly repeatable. The Helmholtz transducer is made up of a stack of 5 piezoelectric ceramic rings inside an oil-filled rubber boot. Each ring is pre-stressed so the ceramic remains in compression while operating. The physical dimensions of the source are 0.7 meters in diameter by 1.08 meters (3.5 feet) in length, weighing 812 kg (1790 lbs) in air and 612 kg (1349 lbs) in water.

The transmit voltage response of the source is plotted below.

Deep Water Source - Transmit Voltage Response

Graph showing source TVR response

image: Photo of source

Applications

The Deep Water Acoustic Source bridges the gap in scale between conventional surface-tow seismic systems and high resolution sidescan systems. This source has applications in high resolution sub-bottom seismic studies such as:

geotechnical studies for sea floor structure emplacement
gas hydrate distribution and characterization
sub-bottom geologic processes

This source can also be used in acoustic applications. For example:

acoustic characterization of the sea floor and ocean subbottom
acoustic tomography
acoustic backscatter studies

Two of these sources are currently under construction; one for the U.S. Navy and one for commercial use.

Photo credits:
top - Brian Spychalski, High Tech Inc.
center - George D. Hugus, USRD Inc.

Last updated: 16 December, 1999.