USA As Represented by Secretary of the Navy

Other

Dehua Huang

Thomas R Howarth

Gaivorlor D Borbor

Scott K Mayer

Roy C Elswick

Gregory A Blasdell

M A Breazeale

A method is given for a broadband constant beam width acoustic array using shading function parameters for a three dimensional axially symmetric beam. Coefficients are calculated for an estimated shading function fitting the parameters that is a summation of Legendre polynomial orders. The number of orders is user specified. Null bearing locations can be determined from the parameters or from the shading function. A constant beam width shading function can be created from these parameters and used as amplifications and attenuations for a conical spherical array of transducers. The array can be truncated at the null bearing locations. The estimated shading function can be further refined by provided additional Legendre polynomial orders.

Truncated constant beam width array method

A method for providing a broadband constant beam width acoustic array includes providing a transducer array in an axisymmetric configuration. A beam width is specified, and an integer order Legendre polynomial is determined for that beam width. A control parameter is determined that will increase the integer order Legendre polynomial to that beam width. The Legendre polynomial is used to provide a shading function for the array of transducers that will give the specified beam width.

Constant beam width acoustic transducer design method

A method for calibrating an acoustic calibration tank providing the tanks with reference hydrophones positioned along the tank. The tank is filled with a fluid at a known temperature and pressure. A calibrated reverse hydrophone is positioned in the tank, opposite one of the reference hydrophones. A known acoustic wave is created in the tank using the calibrated reverse hydrophone and the opposite reference hydrophone output is measured. Free field voltage sensitivity is computed for the reference hydrophone. This gives the calibration factor for the reference hydrophone. The calibrated reverse hydrophone can be repositioned. An iterative process can be utilized for the other reference hydrophones, and other known pressures and temperatures.

Reverse acoustic calibration method

A method for providing a broadband constant beam pattern acoustic array includes providing an array of transducers in a known three dimensional axisymmetric spherical configuration with each transducer element having an associated signal. A user can specify a far field beam pattern for the array. Weightings are calculated for each transducer in the array as being proportional to the voltage that gives the beam pattern power level associated with the bearing for each transducer. Signal power levels for each transducer are modified in accordance with the weightings. The array can be operated for receiving and transmitting signals with a constant beam pattern over a broad range of frequencies.

Constant beam pattern array method

A carbon nanotube thermophone is provided. The thermophone includes high temperature rated shells as protective walls as the top and bottom housing of the thermophone with carbon nanotube sheets affixed between the shells. The shells act as acoustic windows that match the surrounding frequency and acoustic radiation medium. A high temperature rated sealant gasket is used to enclose the shells of the thermophone where gas holes are inserted for interior heavy gas filling. The acoustic resonant frequency is defined by the dimensions of the housing of the thermophone and the sound speed of the filled heavy gas. Each carbon nanotube sheet has an electrode at both ends. Multiple carbon nanotube sheets can electrically tune the impedance to match a driving amplifier impedance load.

Carbon nanotube underwater acoustic thermophone

A carbon nanotube thermophone is provided which includes a urethane frame having mounting holes at corners of the frame. Screw holes in the frame are provided for a cable holder. A square shaped carbon nanotube material chip is positioned within the urethane frame. The carbon nanotube material chip can comprise multiple carbon nanotube sheets to electrically tune the impedance to match a driving amplifier impedance load. Wooden spacers assist in positioning the carbon nanotube material chip. A first end of a cable is soldered to the carbon nanotube material chip at electrodes of the material chip. A high temperature rated silicon sealant is used for attachment points on the thermophone.

Underwater acoustic carbon nanotube thermophone

A passive carbon nanotube transducer is provided. The passive carbon nanotube transducer includes shells as protective walls for the top and bottom housing of the transducer with carbon nanotube sheets affixed between the shells. The shells act as acoustic windows that match the surrounding acoustic medium. A gasket encloses the shells and carbon nanotube sheets of the transducer. Each carbon nanotube sheet has an electrode at both ends. Multiple carbon nanotube sheets are capable of sensing sound induced environment temperature deviations and converting electric voltage or current for passive acoustic detection.

Passive mode carbon nanotube underwater acoustic transducer

A method for using a deployable, small package acoustic transmitter device is taught, which serves as a standard acoustic source for on-vessel, in-mission field calibration purposes. The method involves deploying an acoustic transmitter device underwater to provide a predefined acoustic energy source for sonar array detection as well as periodic time-coded acoustic signal pulses for tracking and calibration of passive ranging.

Acoustic multifunctional standard calibration method

The invention as disclosed is of a combined acoustic pressure and acoustic vector sensor array, where multiple acoustic pressure sensors are integrated with an acoustic vector sensor in a towed array as a means of resolving the left-right ambiguity of the multiple acoustic pressure sensors.

Hybrid pressure and vector sensor towed array

A method that involves establishing the performance level of a proposed acoustic transducer array. Deriving a geometric shape for the array based on the established performance level. Selecting piezoceramic materials based on considerations related to the performance level and derived geometry. Forming small primary shapes of the selected piezoceramic materials for use as the basic elements of the larger derived geometric shape of the array. Arranging the basic elements into a mosaic of the larger derived geometric shape. Filling the interstices between the basic elements with urethane to bind the mosaic of basic elements thereby fabricating the completed piezoceramic transducer array.

Method of fabricating an acoustic transducer array

The present invention presents a method for use with an acoustic sensor array comprised of a number of pressure-vector sensors capable of sensing the acoustic scalar field and acoustic vector field of an acoustic wave. The method is a signal processing technique that utilizes nonlinear processing of pressure-vector sensor signals in the acoustic sensor array. The method involves the steps of receiving the sensor output values, processing the output values using a non-linear algorithm to create a mathematical series of values, transforming the series, applying weighting to the series and performing a summation of the values in the series to calculate the array directivity response. The array directivity response can then be further processed where the array is part of a sonar system.

Nonlinear techniques for pressure vector acoustic sensor array synthesis

A transducer apparatus and method for generating sonic sound waves having a far field wavefront amplitude pattern in a Bessel or Gaussian distribution is disclosed. The transducer includes a piezoelectric element having uniformly poled dipoles formed therein. An unpoled backing body having the same dielecctric constant as the piezoelectric element contacts and is attached to the piezoelectric element. An indentation shaped to produce a beam amplitude distribution of a predetermined function is formed on the backing body.

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Newport, RI, United States of America

Dehua Huang