This paper presents a technique for the absolute calibration of hydrophones using a novel optical method. The method uses a thin, optically reflecting membrane suspended in the acoustic field to allow optical measurement of the acoustic particle velocity using a Doppler interferometer. The hydrophone under test is then substituted for the pellicle, and the hydrophone response to the known acous...

To study delphinid near surface movements and behavior, two L-shaped hydrophone arrays and one vertical hydrophone line array were deployed at shallow depths (<125 m) from the floating instrument platform R/P FLIP, moored northwest of San Clemente Island in the Southern California Bight. A three-dimensional propagation-model based passive acoustic tracking method was developed and used to track...

--Tracking fish has primarily been accomplished using acoustic telemetry. Typically, a fish is tagged, released, and manually tracked using hydrophones that detect acoustic tag transmissions. More recently, such hydrophone receiver systems have been mounted on Autonomous Underwater Vehicles (AUVs) to increase system mobility. This paper presents a new method for determining the distance from a ...

According to Doppler shift of moving acoustic source signal, a method is proposed for identification of noise sources on underwater moving target with single hydrophone. The weak Doppler shift curves due to target moving are obtained by utilizing high accuracy ST-Chirp-z algorithm. Considering the sources with small frequency interval, high frequency resolution ST-ESPRIT algorithm is used to ex...

Near-field ultrasonic response (50-2000 kHz) of an underwater 1-3 piezocomposite transducer is experimentally investigated using a polarimetric polarization maintaining fiber sensor. Measured outputs from our sensor and a reference hydrophone are observed to be comparable.

In an environment such as underwater channel where placing test equipments are difficult to handle, it is much practical to have hardware simulators to examine suitably designed transceivers (transmitter/receiver). The simulators of this kind will then allow researchers to observe their intentions and carry out repetitive tests to find suitable digital coding/decoding algorithms. In this p...

Simultaneous audio and video were recorded of a silver perch Bairdiella chrysoura producing its characteristic drumming sound in the field. The background noise contribution to the total sound pressure level is estimated using sounds that occurred between the pulses of the silver perch sound. This background contribution is subtracted from the total sound to give an estimate of the sound pressu...

As statistical independence exists between marine mammals sound and watercraft emitted noise and among different organism signals, the study introduces blind source separation into marine mammal signals processing. Blind source separation with single hydrophone is a special underdetermined blind separation problem and blind source separation based on matrix calculating is no longer suitable. Th...