The Acoustics and Seismics department of the Vessels and Onboard Systems Department uses acoustic measurement devices to test transducers and hydrophones. It carries out these measurements for its own use, for use by the scientific community or for industry players. Depending on the range of frequencies, the tests can be carried out at sea, in the trial pool or in the department’s acoustic trial tank.
Use of an acoustic tank (Length: 4m; Width: 2.5m; Depth: 2m) enables the department to carry out measurements of emission and receiving sensibility, directivities using a stepping motor (resolution of 0.03°), and electrical impedances, within the range of frequencies [8 kHz, 1 MHz], for a maximum load of 50 kg. Associated laboratory equipment includes etalon transducers, signal synthesisers, power amplifiers, low-noise voltage amplifiers, digital oscilloscopes, and impedance bridges. This equipment can betransported to the large trial pool (Length: 50m; Width: 13m; Depth: 10/20m) for lower frequency measurements, from 1.5 kHz, and for maximum loads of 500 kg.
The software controlling the measurement and acquisition channel was developed internally.
Since 2002, and for about four years, significant efforts have been made to modernise this trial equipment, by acquiring new generation metrology equipment and by internally developing new software adapted in Visual Basic. At the moment, all Visual Basic software for acoustic measurement (Electrical impedances, Sensibility, Directivity, and Reciprocity) is operated from a PC under Windows XP. A new function has also been added to these programs: the simultaneous measurement of directivity at several frequencies.
Regular calivration of electro-acoustic etalon sensors is carried out using the reciprocity method.
Calibration transducer placed on the rotating
Stepping motor on upper part
Etalon transducer on the second rod
Emitter-Receiver distance and depth of
etalon are adjustable
Visual Basic Interface / Measurement of multi-frequency directivity
Brüel & Kjær B&K8101, B&K8104, B&K8105, B&K8106
NF Electronic Instruments 1930A
NF Electronic Instruments 4005 (100 VA)
Low-noise voltage amplifiers
Signal Recovery PAR 5113
Lecroy série 9310
Hioki 3532 LCR Hitester