Title :
A new modular instrumentation for ocean acoustic tomography, present status and future trends
Author :
Gac, C. ; Le Gall, Y. ; Terre, T. ; Leduc, B. ; Person, R.
Author_Institution :
IFREMER, Plouzane, France
fDate :
28 Sep-1 Oct 1998
Abstract :
In 1994, IFREMER launched the development of a new modular instrumentation for meso-scale OCEAN Acoustic Tomography (OAT). Previous instruments made by Woods Hole Oceanographic Institution (WHOI), Webb Research Corporation (WRC) and IFREMER are actually not adapted to basin scale studies (@1000 km). The new autonomous instrument is made up of a wide-band unlimited depth acoustic source, a high efficiency class D power amplifier, a programmable multi-function receiver, a long baseline positioning system and a low power high stability clock. Because of great depth and high efficiency requirements, the Janus-Helmholtz transducer technology was well suited to the long range OAT applications. For the 1997 CAMBIOS experiment, the instrument has been deployed in Atlantic at a 600 m depth. The working central frequency is 400 Hz and 600 km ranges are expected. In parallel to the source development, a 1 Gbyte storage capacity autonomous receiver able to work in various frequency bands has been realised. Fully compatible with the acoustic source, it can be used for standard OAT experiments. Following a description of the present instrumentation and the first result of CAMBIOS experiment, the evolution of the autonomous instrument for the near future is presented: a new optimised 250 Hz Janus-Helmholtz transducer for basin scale studies, a high stability rubidium clock, a four hydrophones receiving array and a multi-channel receiver, and the possibility to make a reliable acoustic control of all instruments from surface
Keywords :
acoustic tomography; acoustic transducers; oceanographic equipment; oceanographic techniques; underwater sound; 400 Hz; CAMBIOS; IFREMER; Janus-Helmholtz transducer; OAT; acoustic instrument; acoustic tomography; autonomous instrument; class D power amplifier; equipment; high stability clock; long baseline positioning system; measurement technique; meso-scale OCEAN Acoustic Tomography; modular instrumentation; ocean; programmable multi-function receiver; underwater sound; wide-band unlimited depth acoustic source; Acoustic transducers; Broadband amplifiers; Clocks; Frequency; High power amplifiers; Instruments; Oceans; Sonar equipment; Stability; Tomography;
Conference_Titel :
OCEANS '98 Conference Proceedings
Conference_Location :
Nice
Print_ISBN :
0-7803-5045-6
DOI :
10.1109/OCEANS.1998.726262