Abstract: This invention is a thermoacoustic system for communicating between an airborne or spaceborne vehicle and a sound detector that is located aboard an object beneath the surface of the water. The foregoing system comprises a laser or particle accelerator that is located aboard an airborne or spaceborne vehicle. The laser produces a light beam whose amplitude is subsequently modulated or whose pulses are varied in time. A particle accelerator would produce a pulsed particle beam that varies in time. These modulated or varied pulses are focused or deflected to a small layer of water at the air/water interface so that the beam will be absorbed by the water causing the water to produce an acoustic signal that will propagate to the sound detector.

Abstract: A damping entity comprises a matrix of plural viscoelastic particles, typically between 0.05 in and 0.5 in in size, which slightly and fixedly contact one another. The particles generally bond with each other at their contact zones and approximately correspondingly therewith. Suitable particle viscoelasticities are defined by either or both of: (i) an approximate shear modulus range between 10 p.s.i. and 100,000 p.s.i.; and, (ii) an approximate loss factor range between 0.05 and 1.5. The particles which describe the matrix can be essentially identical in terms of size, shape and material composition, or can vary among themselves in one or more of these respects. These properties can be selected uniformly or more or less nonuniformly among the particles of a particular matrix in order to imbue the matrix with desired damping characteristics, e.g., in terms of frequency ranges and temperature ranges.

Abstract: A micro-machined ultrasonic transducer (MUT) having aperture, elevation and apodization controlled by apparatus located on the same substrate as the transducer, or by bias voltage control applied to MUT elements, allows for an efficient and compact ultrasonic probe. The control apparatus may take the form of field effect transistors (FET's), micro-machined relays, or doped regions on the substrate, or any other apparatus that may be located on the same substrate as that of the transducer, or by bias voltage sources connected to the MUT elements.

Abstract: An acoustic/video processing stack of a plurality of substantially identical acoustic/video processing stacks is provided for attachment to a processing stack backplane and which together generate a VGA signal for display of a three-dimensional acoustic image. The acoustic/video processing stack includes a two-dimensional array of transducer elements, a companion chip block coupled to and adapted to transceive acoustic signals under a time-division multiplexed format through the transducer elements and to provide a portion of the VGA signal together generated by the plurality of acoustic/video processing stacks and a backing block disposed between the two-dimensional array and companion chip block and adapted to acoustically isolate the two-dimensional transducer array from the companion chip block, said companion chip block and backing block being of a size and diameter substantially the same as the two-dimensional transducer array.

Abstract: The thermohydraulic principle is utilized for generating intensive ultrasonic fields. At least two electrodes which enclose a volume with an electrolyte are driven by a power pulse generator. The electrolyte volume to be heated by the electrical pulse is delimited to such an extent that the electrical power to be applied can be controlled by semiconductor switching elements.

Abstract: A reconnaissance/surveillance system for remote viewing of a selected location while providing a standoff distance from the selected location for personnel controlling the reconnaissance/surveillance system includes a remote controlled underwater vehicle and a delivery vehicle formed to deliver the remote controlled underwater vehicle to an underwater deployment position. An operator control console in the delivery vehicle is connected to the remote controlled underwater vehicle via a fiber optic communications link. A battery powered propulsion apparatus moves the remote controlled underwater vehicle through water to a viewing station under control of the operator control console. The remote controlled underwater vehicle includes sensing apparatus that provides signals that the operator control console uses to navigate the remote controlled underwater vehicle to the viewing station.

Abstract: The invention relates to a seismic acquisition device in a marine environment. The device comprises a Janus Helmholtz (12) transducer which is able to operate at a large depth of immersion and to sound waves in a wide frequency band, a calculator (13) to program at will the frequency band and the form of the sound waves emitted by the transducer, a power amplifier (14) that can control the transducer in order to provide the emitted sound waves with predetermined power levels, an impedance adapter (16) placed between the transducer (12) and the amplifier to enable wide band and power adaptation, and a receiver (18) to capture the seismic waves reflected by the different layers of the sea bed.

Abstract: An apparatus for phase angle demodulation. The apparatus functions as a highly-linear angle-modulation demodulator and is particularly useful for seismic streamers comprising very-large arrays of optical hydrophones. The apparatus includes a demodulator and a processor in which the demodulator contains a signal input and a reference input. The apparatus is configured such that a phase modulated signal having a carrier frequency is connected to the signal input, and a reference signal is connected to the reference input. A difference frequency is defined as the non-zero difference in frequency between the reference signal frequency and the carrier frequency. The processor filters the output from the demodulator in order to separate the phase demodulated signal from the difference frequency.

Abstract: A method and a seismic sensor using symmetrical spring geometry to overcome the temperature sensitivity problems associated with seismometers. The seismic sensor includes a base having a pivot point and a vertical axis. The sensor also includes a neutral axis and a carriage that is mounted to the base at the pivot point. The carriage includes a mass, a boom, a center of gravity, and a neutral position. The carriage is in the neutral position when the center of gravity of the carriage is along the neutral axis. Also included in the sensor is a spring, that is attached to the carriage. The spring suspends the carriage in the neutral position and supplies a force that impels the carriage into the neutral position. The spring being symmetrical about the neutral axis while the carriage is in the neutral position. The sensor further includes a first point and a second point for attaching the spring to the carriage and a detector. The detector is attached to the base and senses the displacement of the carriage.

Abstract: A digital transmit beamformer system with multiple beam transmit capability has a plurality of multi-channel transmitters, each channel with a source of sampled, complex-valued initial waveform information representative of the ultimate desired waveform to be applied to one or more corresponding transducer elements for each beam. Each multi-channel transmitter applies beamformation delays and apodization to each channel's respective initial waveform information digitally, digitally modulates the information by a carrier frequency, and interpolates the information to the DAC sample rate for conversion to an analog signal and application to the associated transducer element(s). The beamformer transmitters can be programmed per channel and per beam with carrier frequency, delay, apodization and calibration values, For pulsed wave operation, pulse waveform parameters can be specified to the beamformer transmitters on a per firing basis, without degrading the scan frame rate to non-useful diagnostic levels.

Abstract: A small target weapon (STW) delivers a warhead to a remote target and detonates it in response to remote command signals from a swimmer delivery vehicle (SDV) and internal control signals generated by a self-contained internal electronics section. When deployed from the SDV, STW is capable of traveling several nautical miles underwater. The STW contains a warhead section and has a spool of optical fiber disposed aft to deploy optical fiber from the housing as it transits through water from a submerged delivery vehicle. Motor-driven propellers disposed aft on the housing of the STW propel it the through the water, and a mast member extends above the housing. Control fins disposed aft on the housing, a vertical thruster and the motor driven propellers are controlled by electronics sections and guidance and control sections to selectively keep the housing beneath the surface of the water and the mast member extending through the surface.

Abstract: A mine neutralization device (MND) is deployed from launch platform, such as an aircraft or surface craft, and travels several miles underwater to destroy a mine. Optical and/or acoustic command signals are coupled to the MND through an optical fiber and ambient water to control the MND on its way to the mine. The MND has a visible light system to illuminate the region around the MND, a camera system to provide optical data signals, and a sonar system to provide acoustic data signals transmitted to the launch platform. The optical and acoustic data signals are representative of images of features in the region to permit control signals from the platform to navigate the MND along the marine topography until the mine is located and identified. Once the mine is located and identified, explosives aboard the MND are detonated to destroy the mine.

Abstract: An active sonar system with improved noise-limited performance in littoral regions with reverberation. This invention solves the active sonar comb-waveform power-limitation problem by introducing for the first time a system employing a new comb waveform herein denominated the triplet-pair comb waveform. Ambient noise-limited performance of the system of this invention is superior to that of systems employing other Doppler-sensitive waveforms such as the geometric comb waveform. Reverberation-limited performance of the system of this invention is slightly inferior to that of systems employing other Doppler-sensitive waveforms but this invention eliminates much of the range ambiguity problems seen with other non-comb waveforms.

Abstract: Acoustic transmitting antennas in the form of circular rings. Several circular rings which can be dismantled of a known type are superimposed in a stack. The stack is terminated at each end by two profiled annuli. The threaded tie-rods traverse the stacks of the pre-stressing keys of the rings by the intermediary of holes drilled in these keys. The threaded tie-rods make it possible to ensure the holding of the assembly. Two jackets, inside and outside, made of rubber, cover the inside and outside faces of the stack and are anchored in grooves formed in the profiled annuli. Thereby, annular transmitting antennas can be provided which can be dismantled entirely and whose active mass to inactive mass ratio is particularly large.

Abstract: The present invention relates to a radar video display and recording device, which can simultaneously display radar video signals of the whole and designated areas in the polar coordinates and Cartesian coordinates, respectively, and can store the radar video signals of the designated area in a hard disk drive (HDD) for obtaining long-time continuous radar video information for subsequent analysis and algorithm verification. A radar video capture card is utilized on a personal computer (PC) or workstation platform to analyze and store radar video signals of the whole and designated areas and to simultaneously display video signals at different processing stages in a digital video processing unit on a scope for monitoring the work condition at each processing stage.

Abstract: The present invention relates to an electromechanical converter, a method of manufacturing same, as well as to a composite system including the electromechanical converter. The inventive electromechanical converter consists of at least one elongate fiber (1) made of a piezoelectric material. At least two electrodes (2) are provided at mutually spaced locations on the fiber (1) for subjecting the fiber to an electrical field. The electrodes (2) are in direct contact with the fiber (1) and enclose the fiber (1) partly or completely. The direct contact between the electrode and the fiber permits the optimum introduction of the electrical field into the fiber such that lower electrical potentials on the electrodes are sufficient for polarising the fiber. Another advantage resides in the aspect that the electrode is in direct contact with the fiber not only at one point but over part of the periphery of the fiber. This results in a further enhancement of the introduction of the electrical field.

Abstract: A radar apparatus is provided which is capable of discriminating between azimuth angles of two or more targets moving side by side close to each other. The radar apparatus provides antenna beams which partially overlap with each other to define a plurality of monopulse areas and processes input signals produced in each of the monopulse areas to obtain angular direction data. The radar apparatus determines a time-sequential variation in angular direction data in each of the monopulse areas and determines the angular direction data whose variation is within a preselected allowable range as being effective in determining the angular direction of each target correctly.

Abstract: A food flagging device has a flag stem, a time identification means, a magnet support platform, and a magnetic means. The time identification means is either attached to, or is contained within, the flag stem. The magnet support platform is either attached to, or is contiguous with, the flag stem. The magnetic means is attached to the magnet support platform and has a magnetic field that is sufficiently strong to hold the food flagging device to a stainless steel surface. The food flagging device is heat-resistant and is capable of being sanitized.

Abstract: This invention is a communication system utilizing sharply bandlimited waveforms for sampled data communications computed for each sample value in a sequence of data samples. The computed waveform is centered at a sample point, weighted by a corresponding data value, and truncated outside an appropriate time interval. Sampled digital data in a sequence of data samples is received by a computer and scaled according to the value r(tn). A waveform generator, controlled by a computer, generates a sharply bandlimited keying waveform for each data sample and weights each waveform with the data and forms the sum of weighted waveforms to form the output signal in digital form which is converted to analog form. The analog output of the waveform generator is passed through a low-pass filter to filter out any harmonics generated, up-converted to produce a desired carrier frequency which can then be multiplexed, if required, and output as radio frequency (RF) energy which can be received by any standard receiver.

Abstract: A Mono-Blade Antenna is disclosed which operates over many octaves of bandwidth. Electromagnetic waveforms may be transmitted and received with multi-decade bandwidth using: a metal ground plane, a Mono-Blade Antenna element fixed above the ground plane, and a coaxial transmission line feed which is connected to the antenna element and the ground plane. The antenna element has three sections: a throat, a mouth, and a radial tip. The throat is comparatively narrow and serves as the element feed point by being connected to the center conductor of the coaxial cable. The mouth is the mid-section of the antenna element, which is the widest section of the blade. The tip of the blade is formed by an arc of approximately constant radius, which results in a low voltage standing wave ratio.