Abstract: The invention as disclosed is of a coaxial transducer that uses lead zirconate titanate ceramic or other suitable material as an isolator between the conductors in a coaxial cable to transmit acoustic power at useful levels. The lead zirconate titanate ceramic is diced into thin disks and placed in between spacers made of much stronger insulating material. The coaxial cable is then integrated into a conventional double-armored steel tow cable with a typical diameter of 1?. This provides substantial longitudinal strength and provides crushing resistance to the lead zirconate titanate ceramic when the cable is being deployed or retrieved over a sheave under tension.

Abstract: A coaxial transducer that uses lead zirconate titanate ceramic or other suitable material as an isolator between the conductors in a coaxial cable to transmit acoustic power at useful levels. The lead zirconate titanate ceramic is diced into thin disks and placed in between spacers made of much stronger insulating material. The coaxial cable is then integrated into a conventional double-armored steel tow cable with a typical diameter of 1?. This provides substantial longitudinal strength and provides crushing resistance to the lead zirconate titanate ceramic when the cable is being deployed or retrieved over a sheave under tension.

Abstract: A system and method are provided for launching and recovering an unmanned, water-borne vehicle (UWBV) from a mother ship. The UWBV mimics the behavior of dolphins and is positioned ahead of the ship in preparation for bow riding. The UWBV uses a guidance system to position and keep in the bow wave. A high-frequency (HF) sonar transceiver array aboard the ship computes and sends course corrections to maintain the UWBV within the bow wave. The frequency range of the HF array can be 100 kHz or higher due to the short distance between the ship and the UWBV. Accordingly, the HF array can have a small aperture allowing for accurate bearing resolution. Course corrections can be sent on a near-continuous basis such that changes in thrust and rudder angle can be minimized to allow for accurate control of the UWBV.

Abstract: A transducer with a closed heat pipe is provided with a hot surface and a cold surface. The hot surface is in contact with the transducer interior and the cold surface is in contact with a cooler contact area. A fluid is used in the pipe which boils at the temperature of the hot surface and condenses at the temperature of the cold surface. A wick inside the heat pipe facilities the return by capillary action of the condensed fluid to the hot end. The heat pipe can be evacuated to adjust the boiling temperature of the fluid. A variant involves drilling additional holes into ceramic rings and inserting heat pipes. Increasing the heat pipe length into the tail mass and the piston increases the cool region for the fluid to condense; thereby improving the performance of the transducer.

Abstract: A marine acoustic sensor assembly includes an acoustic panel having a forward surface and an after surface, a laser scanner oriented so as to project a laser beam onto the acoustic panel after surface, and a sensor oriented so as to receive reflections of the laser beam off the acoustic panel and to transmit data from which a position of a sound generating source can be determined, wherein the acoustic panel is provided with an absorber layer extending over the after surface thereof, and the absorber layer is provided with holes extending therethrough, the holes being of a size sufficient to permit passage of the laser beams to the acoustic panel after surface and the reflections to pass to the sensor, whereby to minimize reflections and noise originating from aft of the after surface, while permitting sound incoming from forward of the acoustic panel to be measured.

Abstract: The present invention relates to an optical fiber cable for use with a system for determining a velocity profile of sound in a medium. The optical fiber cable comprises an inner layer of strength members, an outer layer of strength members, and at least one tube containing at least one optical fiber incorporated into the outer layer. The at least one optical fiber has a plurality of Bragg grating sensors spaced along its length.

Abstract: A method for determining the direction of an incoming signal is provided in which each of a plurality of receivers arranged in a linear array is sampled in sequence to simulate a single receiver moving along an aperture defined by the linear array at a simulated speed. This generates a simulated time series data from which a simulated Doppler shift in the incident angle is measured. The simulated Doppler shift is used to determine the incident angle between the incident signal and the linear array of receivers. By adjusting the simulated speed to eliminate artifacts in the power spectral density of the data obtained from the receivers, the incident angle can be obtain from the expression of the simulated Doppler shift.

Abstract: A tow body is provided with an attachment point to connect to a tow cable. The attachment point is positioned nominally at a nonzero angle relative to the length of the tow body. Propulsion components of the body generate thrust. The body is capable of accepting electric power for a propulsion motor within the body. The motor provides the power for the propeller or other propulsion equipment. The power for the motor can also provided by a tow cable. The addition of forward thrust by the propeller decreases cable scope (the need for long lengths of cable) and required winch volume for storing the cable.

Abstract: A marine acoustic sensor assembly includes an acoustic panel having a forward surface and an after surface, a laser scanner oriented so as to project a laser beam onto the acoustic panel after surface, and a sensor oriented so as to receive reflections of the laser beam off the acoustic panel and to transmit data from which a position of a sound generating source can be determined, wherein the acoustic panel is provided with an absorber layer extending over the after surface thereof, and the absorber layer is provided with holes extending therethrough, the holes being of a size sufficient to permit passage of the laser beams to the acoustic panel after surface and the reflections to pass to the sensor, whereby to minimize reflections and noise originating from aft of the after surface, while permitting sound incoming from forward of the acoustic panel to be measured.

Abstract: A method for determining the direction of an incoming signal is provided in which each of a plurality of receivers arranged in a linear array is sampled in sequence to simulate a single receiver moving along an aperture defined by the linear array at a simulated speed. This generates a simulated time series data from which a simulated Doppler shift in the incident angle is measured. The simulated Doppler shift is used to determine the incident angle between the incident signal and the linear array of receivers. By adjusting the simulated speed to eliminate artifacts in the power spectral density of the data obtained from the receivers, the incident angle can be obtain from the expression of the simulated Doppler shift.

Abstract: A method for estimating uncorrelated noise in a distributed record of data including data samples that represent both signal and noise, provided that the signal is substantially in phase between adjacent data samples. The method begins with dividing the record of data into an even number of equal intervals. The method proceeds compiling a reduced data record by subtracting from every other data sample in the record of data one data sample that is adjacent to it. Finally, the method entails a step of estimating the noise power in the signal relative to the signal power by calculating the standard deviation as a measure of the magnitude of the noise.

Abstract: An underwater RF signal propagation path is created by utilizing a plurality of individual RF transceivers such as MEMS RF transceivers. Each MEMS RF transceiver has a predetermined buoyancy. A stream of the RF transceivers are released to form a line of RF transceivers underwater such that the individual RF transceivers have an RF transmission and reception distance greater than the distance between the RF transceivers whereby an RF signal can be repeatedly retransmitted down the line of RF transceivers.

Abstract: A sonar dome having an acoustic array housed therein. A plurality of bubbles are generated within the fluid inside the sonar dome. The generated bubbles are of an amount and size to reduce the speed of sound within the sonar dome fluid. Reduction of the speed of sound within the sonar dome fluid effectively increases the aperture of the acoustic array. The bubbles can be generated from a gas source or electrolytically. Typically, each individual bubble is less than 0.01 mm in diameter to reduce bubble velocity in the fluid.

Abstract: A miniature lightweight transmitter that mechanically generates low-frequency acoustic energy is described, wherein one or more miniature balloons filled with air are positioned at the center of a pressure vessel filled with water and tethered in place. The system is then driven into resonance by using transducers that directly drive the wall of the pressure vessel or by using a piston to drive fluid into and out of the pressure vessel.

Abstract: A method and apparatus of switching a digital signal from a single input optical fiber to one or more optical fibers comprising the steps of providing an input signal into the input optical fiber, splitting the input optical fiber to form a plurality of split optical fibers each carrying the input signal, amplifying the signal in at least one of the plurality of split optical fibers with a laser activated amplifier, and then attenuating the signal in all of the split optical fibers to produce at least one output signal in one or more of the designated split optical fibers.

Abstract: A method of switching from a single input optical fiber to one or more output fibers comprising the steps of providing an input signal into the input optical fiber, splitting the input signal and the input optical fiber to form a plurality of optical fibers and a plurality of split input signals each of the optical fibers carrying a single one of the plurality of the split input signals, attenuating the plurality of the split input signals, amplifying at least one of the plurality of the split input signals with a laser activated amplifier to produce at least one output signal, and outputting the at least one amplified split input signals through corresponding at least one output fibers.

Abstract: An integrated fiber-optic tow cable is described having both optical fibers and armor wires located outside the cable core to avoid high strain on the optical fibers when the cables is under stress during deployment. The optical fibers have integral temperature sensors near the outermost portion in order to measure accurately the temperature of the fluid coming in contact with temperature sensors. A beam of light is shown on the optical fibers which is reflected by the optical fibers and reaches the receiver and processed by the processor which may also include a display unit.

Abstract: A tow cable in which the temperature of the cable is measurable by the use of multiplexing capability intrinsic to optical fibers in which the optical fibers are positioned at the center of the tow cable and wound as part of two layers of surrounding strength wires. The optical fibers of the two layers intersect a vector extending radially from the optical fiber at the center to an outer surface of the tow cable. Light signals emitted from a multiplexer to positions along the optical fibers, in which the positions intersect the vector, return light signals from the positions to provide measurements that in conjunction with a data processor further provide temperature measurement of the outer boundary of the tow cable.

Abstract: A method is provided for estimating the size of an object from a region of a fluid medium when that object is emitting acoustic radiation of known wavelength ? on its own or as the result of being interrogated by acoustic pulses that reflect from the object. The acoustic radiation is monitored using a line array of N acoustic receivers such that N signals indicative of the acoustic radiation are generated. M time series summations are formed using the N signals. Each of the M time series summations is formed using a unique time delay predicated on a corresponding unique estimated speed of propagation of the acoustic radiation where M estimated speeds of propagation are defined. For an object in the region having a diameter D on the order of ?, the M values will vary as a function of the M estimated speeds of propagation with the resulting distribution of the M values being indicative of diameter D.

Abstract: A safety device for reducing the likelihood of superheating a liquid includes a transducer disposed on a support surface proximate to a placed container containing a liquid. The transducer generates a vibrational force in the container and onto the liquid that creates nucleation within the liquid. The nucleation allows the liquid to boil, thus preventing the liquid from becoming superheated.