The general theory of a diaphragm fiber-optic sensor (DFOS) is proposed. We use a critical test to determine if a DFOS is based on Fabry-Perot interference or intensity modulation. By use of the critical test, this is the first design, to the best of our knowledge, of a purely Fabry-Perot DFOS, fabricated with microelectromechanical system technology, and characterized as an audible microphone ...

The Sonar Performance Prediction System (SPPS) will be introduced. The SPPS is an integrated ocean-acoustic propagation model coupled with a sonar performance prediction model. A stationary sea surveillance sonar consisting of a horizontally nested hydrophone array and a vertical transmitting/ receiving array may be used lo dctcct, localisc and track surface and subsurfacc contacts within its c...

This article focuses on techniques for position reconstruction of acoustic point sources with the AMADEUS setup consisting of 36 acoustic sensors in the Mediterranean Sea. The direction reconstruction of an acoustic point source utilizes the information of the 6 small-volume hydrophone clusters of AMADEUS individually. Source position reconstruction is then done by combining the directional inf...

The goal of this work was to determine the acoustic waveform and beam width at the focus of a therapeutic ultrasound source both in water and in a tissue phantom. The source was a 2 MHz transducer of 45 mm focal length, 42 mm diameter, operating at 50 300 W acoustic power. Focal waveforms and beam widths calculated with a KZK-type model were in excellent agreement with values measured with a 10...

An Angular Spectrum Approach (ASA) is formulated and employed to simulate linear pulsed ultrasound fields for high bandwidth signals. A geometrically focused piston transducer is used as the acoustic source. Signals are cross-correlated to find the true sound speed during the measurement to make the simulated and measured pulses in phase for comparisons. The calculated sound speed in the measur...

A notable sequence of calls was encountered, spanning several days in January 2003, in the central part of the Indian Ocean on a hydrophone triplet recording acoustic data at a 250 Hz sampling rate. This paper presents signal processing methods applied to the waveform data to detect, group, extract amplitude and bearing estimates for the recorded signals. An approximate location for the source ...

The present study describes the development and testing of a tool for dolphin research. This tool was able to visualize the dolphin echolocation signals as well as function as an acoustically operated "touch screen." The system consisted of a matrix of hydrophones attached to a semitransparent screen, which was lowered in front of an underwater acrylic panel in a dolphin pool. When a dolphin ai...

This paper presents the design, manufacturing and testing of a Dual Accelerometer Vector Sensor (DAVS). The device was built within the activities of the WiMUST project, supported under the Horizon 2020 Framework Programme, which aims to improve the efficiency of the methodologies used to perform geophysical acoustic surveys at sea by the use of Autonomous Underwater Vehicles (AUVs). The DAVS h...

When an ultrasonic pressure wave propagates through a nonlinear medium, the relative phasing of the generated harmonics causes a distinct asymmetry between the positive and negative pressure levels and between the rise and fall time of examined waveforms. A faithful quantitative reproduction of the source transducer's pressure field requires amplitude and phase measurements by calibrated hydrop...

A passive acoustic method is presented for tracking sperm whale dive profiles, using two or three hydrophones deployed as either a vertical or large-aperture towed array. The relative arrival times between the direct and surface-reflected acoustic paths are used to obtain the ranges and depths of animals with respect to the array, provided that the hydrophone depths are independently measured. ...