Abstract: A system and method is provided to replenish a submarine's tactical capabilities, e.g., weapons, sensors and communications, while the submarine remains within a hostile environment. One or more Underwater Combat Vehicles (UCV's) are pre-positioned at strategic locations or are launched from a surface and/or airborne platform. The UCV's include full tactical capabilities, which can attach to and be integrated with a submarine's capabilities. To initiate replenishment, a submarine broadcasts a signal, or dispatches one of the UCV's under its direct control, to make contact with one of the pre-positioned UCV's or with a central command platform. The pre-positioned UCV's are programmed to search for and locate the submarine. This can either be accomplished using signals broadcast from the submarine, or using UCV internal navigation systems and a last known position for the submarine.

Abstract: An alarm arrangement for swimming pools includes an electronic transmitter unit (16) and an electronic receiver unit (18). The transmitter unit (16) has a housing (20) containing electronic circuitry. Water activated electrical contacts (24, 26) are provided outside the housing (20) for causing energization of the electronic circuitry when coming into contact with water for emitting an ultrasonic operative signal when a person wearing the transmitter unit (16) enters into water in a pool. The receiver unit (18) has a housing (36) containing electronic circuitry, water activated electrical contact (54, 56) outside its housing (36) for causing energization of the electronic circuitry when coming into contact with water, for detecting any preselected operative signal from the transmitter unit (16) when the transmitter unit (16) comes into contact with water in a pool so as to emit a suitable alarm signal.

Abstract: The high frequency response of a versatile exercise mine system that emulates potentially threatening mines is extended by an acoustic float system. A watertight housing is buoyed upward from the mine system and has a first acoustic sensor to provide an omni-directional response to higher frequency acoustic signals in the range of 20 to 40 kHz that are transmitted from distant sources through ambient water. A second acoustic sensor adjacent to the first acoustic sensor produces a directional response to the higher frequency acoustic signals. Processing circuits receive signals from the acoustic sensors and generate signals representative of the higher frequency omni-directional and directional responses. An inclinometer generates signals representative of inclination of the acoustic system and a cable feeds the all the representative signals to a versatile exercise mine system for additional processing and/or evaluation.

Abstract: A method and apparatus are provided for automatically characterizing the spatial arrangement among the data points of a three-dimensional time series distribution in a data processing system wherein the classification of said time series distribution is required. The method and apparatus utilize grids in Cartesian coordinates to determine (1) the number of cubes in the grids containing at least one input data point of the time series distribution; (2) the expected number of cubes which would contain at least one data point in a random distribution in said grids; and (3) an upper and lower probability of false alarm above and below said expected value utilizing a discrete binomial probability relationship in order to analyze the randomness characteristic of the input time series distribution.

Abstract: A method is provided for determining multiple feature variances in a medium. Acoustic sources are positioned on one side of a selected scattering direction. Acoustic receivers are positioned on an opposite side of the selected scattering direction such that, for each acoustic source, there is a corresponding acoustic receiver located at a mirror-imaged position relative to the selected scattering direction, and such that a Bragg scattering wave vector associated with each acoustic source/receiver pair is parallel to the selected scattering direction. Each acoustic source is operated at a unique time to direct a broadband ultrasonic pulse at the region of interest. An acoustic scattered wave reflects from the region of interest and is detected as a waveform at the pair's acoustic receiver. Each waveform is converted to the frequency domain to form a spectral waveform. A band of Bragg wave numbers is determined for each spectral waveform.

Abstract: A submersible, hydrostatic pressure tolerant enclosure for a portable audio device is disclosed. Also disclosed is a removable lid allowing for the inserting and removing of the device from the enclosure. The disclosure further provides a connector system and an audio communication link connecting the housing to a device capable of generating sound, and to a device capable of producing sound while being submerged in an aquatic environment. Also disclosed are headsets containing at least one speaker within a waterproof enclosure. The speakers may be positioned in or near the ear canal, and attached to the ear or to the user's equipment. The headsets may further comprise devices for controlling power and fidelity. The disclosed invention provides an affordable, easy to use and flexible appliance for utilizing an audio device while being submerged into an aquatic environment.

Abstract: A digital signal processor is disclosed for analyzing sound signals to determine the identification of the sound and the location of the source of the sound, as well as to present its results as an auditory scene. The processing includes producing a gram representative of a sound signal in time, frequency, and space parameters, and then extracting elements from the gram and features from the elements. The elements and the features are routed to an inference engine, which also receives predefined knowledge from a database. The inference engine derives conclusions, which are used to produce the auditory scene.

Abstract: A system is provided in which a torpedo is launched from a submarine and pays out an optical fiber as it moves away from the submarine towards a target. The optical fiber is attached to the submarine and provides an optical communications link between the submarine and the torpedo. In addition to carrying communications between the submarine and torpedo, the optical fiber includes optical acoustic sensors. The optical fiber serves as a forward deployed acoustic array to gather target bearing and range data that is processed at the submarine. With the array deployed directly within the engagement arena, the submarine can more accurately analyze the acoustic environment to better guide the torpedo through countermeasure avoidance and to target acquisition. The optical fiber pays out behind the torpedo at the same rate that the torpedo moves away from the submarine.

Abstract: A nonlinear signal processing system and method is used to identify nonlinearity (e.g., chaos) in underwater acoustic signals, such as sonar signals. The system and method detects the underwater acoustic signal and digitizes the underwater acoustic signal to produce an acoustic time series. The acoustic time series is reconstructed using a phase space embedding algorithm to generate a phase space embedded acoustic signal. A differential radius signal is generated from the phase space embedded acoustic signal using chaotic radius computations and differential radius computations. Thresholds can be detected in the differential radius signal to reveal nonlinear or chaotic events hidden in the underwater acoustic signal.

Abstract: A submersible, hydrostatic pressure tolerant enclosure is presented for a portable radio, tape recorder/player, minidisk player, mp3 player, cellular phone, or other devices used for projecting audio, in the form of a rigid unified membrane with a built in stereo jack adapter capable of a pressure resistant coupling to a stereo jack. Also presented is a removable rigid lid allowing for the inserting and removing of the device from the enclosure, which is comprised of recessed sealing compression o-rings and control knobs to externally manipulate the internal device. Also provided is a hydraulic coupler system adapted into the frame of the housing that contains a stereo jack adapter that connects to a submersible pressure resistant scuba mask strap speaker system. The speakers have the ability to rotate horizontally and vertically to be positioned near the ear canal or moved out of the way in case of an emergency.

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: An underwater high energy acoustic communications device has inner shell-like structure having an outer surface connected to first ends of tuning springs and outer shell-like structure having an inner surface connected to second ends of the tuning springs to concentrically locate and space the inner and outer structures apart. Explosive units mounted on the inner surface of the outer structure each includes an explosive squib, rigid tube, and projectile. A micro-controller feeds firing signals over electrical leads to the explosive units to detonate them and fire their projectiles to strike the inner structure that emits ringing high-energy broadband acoustic signals that are propagated into surrounding seawater. A transducer connected to the micro controller receives acoustic signals from a remote source to activate the micro-controller to generates preprogrammed sequences of firing signals to propagate coded messages by the high-energy broadband, acoustic signals.

Abstract: A method and system are provided for obtaining acoustic data for use in determining fish populations in shallow waters. The system includes an acoustic source comprising a buoyancy unit, anchor, and a broadband acoustic transmitter, and a cable which connects the buoyancy unit to the anchor and supports the transmitter. The system also includes one or more acoustic receivers employing hydrophones and including a similar buoyancy unit, anchor, and cable. When the source and receiver are (separately) deployed, the respective cables are released so that the buoyancy units rise in the water. Thus, with the source and receiver anchored to the bottom the transmitter and hydrophones are suspended at a depth near the bottom (below the thermocline if there is a thermocline) determined by the cable length released. At this time, acoustic signals are transmitted from the acoustic transmitter to the hydrophones for recording.

Abstract: This invention is a thermoacoustic sonar system for detecting a target that is located at or beneath the surface of the water. The foregoing system comprises a laser or particle accelerator that is located above the water and a plurality of passive receivers that are located on or above the water. 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 may propagate to a target where the acoustic signal will be reflected and possibly detected by one or more passive receivers.

Abstract: The present invention relates to an underwater apparatus, system and method for inspecting and determining the condition of a submerged structure. More particularly the present invention utilizes acoustical devices for the positioning of an inspection vehicle, with respect to the structure to be inspected.

Abstract: An acoustic warning assembly capable of being launched from an underwater vehicle while being underwater. The acoustic warning assembly includes an acoustosensitive member for collecting above-surface acoustic signals. The acoustic warning assembly also includes a carrier member launchable from the underwater vehicle, the carrier member is designed to carry the acoustosensitive member above-surface. The acoustic warning assembly also includes a communication medium for communicating between the acoustosensitive member and the underwater vehicle, for transmitting the above-surface acoustic signals collected by the acoustosensitive member to the underwater vehicle.

Abstract: A detection problem is introduced for a source of some bandwidth and unknown waveform and emission time in the presence of noise of uncertain variance. The signal travels to the receivers along paths whose delays may be unknown. Using a new receiver called a “matched-lag filter,” the presence or absence of the signal is estimated from the auto- and cross-correlation functions of the received signals. The use of correlation functions provides the first stage of gain in signal-to-noise ratio, like a matched filter, because the paths are assumed to be partially coherent with one another. The second stage achieves additional gain by searching only over the physically possible arrangements of signals in the auto- and cross-correlation functions. These stages enable the matched-lag filter to behave like a matched filter within a matched filter. In a simple case, simulations of the matched-lag filter yield probabilities of detection that are, with one and two receivers, 4.

Abstract: The present invention relates to a method for generating 2 and 3-dimensional fluid meshes for structural/acoustic finite element analysis in an infinite medium. The method broadly comprises the steps of: enclosing a structure to be analyzed in a block of fluid; determining a bias factor and coordinates for the mesh; and generating at least one of a two dimensional and a three dimensional mesh using the coordinates and the bias factor.

Abstract: A method and system are provided for communicating in a time-varying medium. A transmitter sends transmissions of the same message data separated in time with respect to one another. A single sensor receives the transmissions. Each received transmission is buffered until all of the transmissions that were sent are received. The buffered transmissions are simultaneously processed via multichannel adaptive equalization only when all of the transmissions that were sent are received.

Abstract: An electronic device for use by recreational divers, that uses ultrasonic signals to measure distance, to indicate relative direction, and to maintain contact between at least two diving partners during a diving session. One of the devices is worn and operated by each diving partner, and each device, through an arrangement of ultrasound transmitters and receiver pairs affixed thereto, monitors relative distance between itself and each other device in use by a diving partner. The device has a user interface, including a plurality of push-buttons and liquid crystal display, to set and indicate relative distance, relative direction, low battery fault, and chime or vibration warning mode. The warning mode alerts a diver when a distance limit between companion divers has been exceeded.

Abstract: The location of a submerged tow vehicle (LOST) system provides a device for accurately determining a position of an underwater vehicle towed by a surface craft or aircraft, such as a helicopter. The LOST system utilizes five sources of input data to compute a best estimate of the towed vehicle's position. These are (1) high resolution bathymetry data in an area of the towed vehicle's transit, (2) ocean depth at a position of the towed vehicle, (3) the towed vehicle's velocity over sea bottom, (4) a slant range from the towed vehicle to a known reference point, and (5) a position and course of the towing vehicle. The LOST system is comprised of a slant range updater, a maximum likelihood estimator, a constrained adaptive tracker and a slant range corrector.

Abstract: A method of correcting errors in in inertial navigation system, without imposing restrictions on the ships course, utilizing bathymetric data collected during the Ocean Survey Program (OSP). As the ship is in transit in or crosses an OSP swath, sonar transmissions commence and continue only to acquire bottom data within data areas of predetermined dimensions. Depth gates and transmission power levels are established in accordance with OSP provided bottom data and depth is determined by an autocorrelation process. A virtual linear map is established with the OSP data in the predicted locations of data collection areas. The collected data is then compared to corresponding OSP data to determine inertial navigation system corrections.

Abstract: An underwater imaging system includes a scuba facemask having a viewing portion that defines a user field-of-view. An imager generates image data of an area in an imaging field-of-view. The imager is coupled to the facemask such that the imaging field-of-view at least partially overlaps the user field-of-view. A display mounted in a lower portion of the user field-of-view is coupled to the imager for displaying images to the user based on the image data.

Abstract: Acoustic intensity is measured by a submerged probe consisting of two passive geophones mounted in spaced relationship with their sensing axes aligned. The geophones are connected through a cable to a remote spectrum analyzer in which acoustic intensity is computed from the velocity gradient between the two geophones. The exclusive use of geophones, which inherently have low impedance outputs, eliminates the need for preamplification in the probe. The geophones are mounted inside an acoustically transparent, thin rubber shell, which reduces the effects of noise due to flow.

Abstract: A system for sonically probing a seabed comprises at least one row of transducers that each can produce a sonic beam, and a corresponding row of sonic detectors. Each transducer is independently energized to produce a narrow sonic beam, with resulting seabed or subsea echoes being detected to produce one pixel of a display formed by an X-Y array of pixels, before a next transducer is energized and its echoes are detected to produce another pixel of the display. When the system detects a large change in echo amplitude at adjacent seabed locations, then scanning at those locations is accentuated by analysis and by additional sonificiation at different frequencies. The transducers are closely spaced, at a center-to-center distance of typically about 3.5 cm, to provide good horizontal resolution. Each transducer is energized to produce a sonic pulse which, dependent on the application, has a carrier frequency of 0.25 MHz.

Abstract: The present invention relates to an intelligent personal underwater monitng system which recognizes when a swimmer is in trouble and transmits a warning signal. The system comprises a device worn by the swimmer which senses water pressure and transmits a first signal when a predetermined depth is passed by the swimmer. The system further comprises a device for receiving the signals generated by the device worn by the swimmer and a neural network processor for processing the signals and generating an output signal representative of whether the swimmer is in trouble and an alarm signal generation device.

Abstract: A system for digitally demodulating optical hydrophone signals is provided. The system includes an optical hydrophone connected to an analog-to-digl converter and further connected to a digital signal processor. Within the digital signal processor, a basic demodulator has a first and second mixing tables, the first table operating at a modulating frequency, .omega., injected into reference legs of the hydrophone, and a second table operating at 2.omega.. The mixer frequencies are coherently mixed with the incoming acoustic signals received by the hydrophone. An automatic calibration circuit which adjusts the phase of the mixers is connected to the basic demodulator.

Abstract: An apparatus and method for imaging uses a transducer array which receives a scattered signal from a region of interest. The method analyses the scattered signal on the basis of a model which assumes several independent point scatterers at each range. The method determines the amplitudes and angles of arrival for the several scatterers. The method provides much higher resolution than is possible with conventional beam formed sonar arrays of practical size. The method is capable of resolving features which cannot be resolved by conventional sidescan sonar or interferometric side scan sonar. The method may be used with electromagnetic or acoustic scattering signals.

Abstract: An apparatus for detecting and monitoring scouring around a structural mer uses time-domain reflectometry (TDR) to measure the level of sediment around a submerged portion of the structural member such as a bridge pier, dock, utility crossing, or similar structure. The apparatus includes a time domain reflectometer which transmits a series of electrical pulses, a sensor which is connected with said time-domain reflectometer, and a signal analyzer which receives and interprets the portion of the electrical pulses reflected back to the source from an interface, such as water/air or water/gravel, to calculate the position of the interface along the sensor. Knowledge of the position of the interfaces before and after a scouring event and of the dielectric constant of the surrounding media allows the user to detect and monitor the level of erosion caused by scouring.

Abstract: A system and method for determining the geographic relationship between a surface station and at least one diver, including a first and second devices for sending passive or active select signal frequencies and receiving select signal response frequencies data. A third and fourth devices for receiving passive or active select signal frequencies data and sending passive or active select signal response frequencies to the first device. A fifth and sixth device for processing data based on a cycle time and a seventh and eighth device for plotting the data received from the fifth and sixth devices.

Abstract: An apparatus for detecting and monitoring scouring of a bed of sediment bath a body of water uses time-domain reflectometry (TDR) to measure the level of sediment adjacent to underwater sensors. The apparatus includes an electrical pulse generator which produces and intermittently transmits a series of electrical pulses along a permanent transmission line arranged adjacent to the area of concern, a timer to measure the travel time of the pulses within the transmission lines, a transmitter for transmitting a radio signal corresponding to the travel times of the pulses, a receiver for receiving the signal, and a signal analyzer which interprets the signal to determine a measurement of scouring. Knowledge of the position of the interfaces before and after a scouring event and the dielectric constants of the surrounding media allows the user to detect and monitor the level of erosion caused by scouring.

Abstract: An acoustic sound speed profiling system is provided. The system includes a sound emitter and a series of sensors or hydrophones spaced vertically in a water column. The sound emitter is a high-frequency sound source adap for mounting on the front end of a passive, towed sonar array. The sound source has a frequency which may be outside the acoustic aperture of the towed array. The series of sensors are located at intervals along and embedded within the array tow cable. The sensors are conventional hydrophones or thin-film hydrophone membranes. During operation of the system, the source transmits high frequency sound, which is received by each sensor along the tow cable of the towed array. Calculation of the speed of sound is determined from the position of the tow cable and the time-of-arrival of acoustic signals at each sensor. There is no interference with the normal operation of the passive towed array.

Abstract: An array of piezoelectric transducers from which acoustical energy is emid at a low and high frequency within a predetermined frequency band, synthesizes a localized underwater simulation of a remotely located explosion pressure field, by programmed computer control over the electrical energy input from a signal frequency generator transmitted through power transfer circuitry to the array of acoustic projecting transducers.

Abstract: A method is described for providing an estimate of the state of a stationary or moving contact in a three dimensional ocean. The method comprises the steps of collecting information about a location of an observer during a sequence of time, information from at least one sensor about a position of the contact relative to the observer during the time sequence, and a knowledge vector. Transforming the information into a series of three dimensional geographical grids. Examining the grids to identify hypothesized contact paths and analyzing the hypothesized contact paths to produce an estimate of the state of the contact with respect to the location of the observer. A device for providing the estimate of the state of a stationary or moving contact includes a grid stimulation block for transforming the collected information into the three dimensional geographical grids. A fusion block where grids corresponding to similar time intervals are combined or fused.

Abstract: A system for surveying an underwater topography includes an ultrasonic sensor array disposable in physical contact with a body of water for generating electrical signals encoding ultrasonic echo responses of underwater objects in the body of water. The sensor array includes a plurality of electromechanical transducers in turn including at least one electroacoustic transducer and one acoustoelectric transducer. The transducers are disposed in a configuration extending in at least two dimensions. An a-c current generator is operatively connected to the electroacoustic transducer for energizing the electroacoustic transducer with an electrical signal of a pre-established ultrasonic frequency. Means are provided which operatively connected to the sensor array for determining locations of the electromechanical transducers relative to one another.

Abstract: A seismic acoustic signal source includes a hull that has a wetted surface in contact with a body of water. When underway, the draft of the hull is substantially zero. An acoustic signal generator is provided with a linear actuator that is resiliently mounted in the hull. The linear actuator is acoustically coupled to the hull bottom such that when the signal generator is activated, the hull radiates an acoustic wavefield into the water.

Abstract: An underwater diving assistant device. In one embodiment, the present invention comprises a hand-held unit including a display screen. Messages and drawings are written on the display screen using a passive electromagnetic pen. Markings on the screen can be instantly cleared, stored or transmitted to another, similar device by placing the electromagnetic pen in proximity to a command icon on the screen. The unit includes standard dive computer functions. In one embodiment, the unit includes a digital camera and a vessel locator, and generates audible tones under various circumstances. In one embodiment, a power source of the unit is stored in a container fastened to a diver's weight belt and is connected by a tether to the unit.

Abstract: A high sensitive water entry alarm system which prevents outside noise from falsely triggering the alarm system. A transmitter generates ultrasonic timed acoustic bursts at a fixed frequency when it is submerged in water. A receiver located in the body of water senses for acoustic signals similar in characteristic to the transmitter signal. A comparing circuit coupled to the receiver compares the acoustic signals received by the receiver to a reference signal having the same fixed frequency as the transmitter signal. The comparing circuit also measures the duration of the acoustic signals received by the receiver. The comparing circuit will generate a alarm signal which will sound off an audible alarm only when the acoustic signal received by the receiver has the same fixed frequency and is transmitted in controlled burst at the same timed intervals as the transmitter signal.

Abstract: A system is disclosed for locating swimmers who could be in danger of drowning, as determined by preset parameters such as the time duration that they remain at a depth where breathing is impossible. In this system, each individual swimmer wears a Swimmer Location Monitor (SLM). This is a miniature electronic device that not only determines the extent of the swimmer's danger but also emits an electromagnetic alarm signal whenever such a danger exists. At each occurrence, an alarm, which may be audible and/or visual, is sounded on the surface while the swimmer's location is tracked in real time from the signals received on an antenna network deployed along the bottom of the swimming area. These signals are combined in a central processor and the computed real-time location is displayed graphically on a monitor to guide the guard personnel in rescue operations. The invention is intended for use in pools, beaches, water parks and other swimming areas.

Abstract: An oceanographic sampling system includes two or more underwater vehicles disposed in an array and an array controller for controlling the array of underwater vehicles as data is acquired. Each underwater vehicle includes a propulsion system for moving the underwater vehicle independently of the other underwater vehicles, a sensor for sensing an ocean parameter and providing sensor data representative of the ocean parameter as the underwater vehicle moves, a navigation subsystem for determining position data representative of the position of the underwater vehicle as the sensor data is acquired and a synchronizing subsystem for time synchronizing the sensor data and the position data acquired by the underwater vehicle with sensor data and position data acquired by other underwater vehicles. The array of underwater vehicles may function as a large aperture phased array, and phased array analysis techniques may be applied to the time-synchronized sensor data and position data.

Abstract: A method for processing acoustic signals received by first and second undater detectors, spaced from each other, for detection and determination of range and bearing of an underwater signal source, includes the steps of obtaining a time series xd of first random variables X from the first detector, obtaining a time series yd of second random variables Y from the second detector, and providing a window of a selected number of digital points of time series xd and yd.

Abstract: An improved pattern recognition system. The invention operates on a plurality of feature vectors from a single class of data samples. The inventive system estimates a pruning radius for the feature vectors in the single class of data samples and generates a replacement class therefrom based on the estimated pruning radius. This pruning radius is used to train a classifier which in turn facilitates the recognition of a data pattern in raw data. In a specific implementation, the pruning radius is adapted based on current results from the classifier. The invention satisfies the need in the art by providing an automated technique for training classifiers for nonstationary data classes which is not limited by the need for more than one class of data.

Abstract: An acoustic transponder method and apparatus provides a high degree of frency and target strength selectivity by utilizing two or more concentrically disposed, hollow spheres each containing acoustically refractive fluids. The invention provides the possibility of using spheres of a variety of diameters and as well a number of different refractive fluids, enabling the production of an acoustic transponder having a wide variety of selective frequency responses as well as effective target diameters.

Abstract: The water/sediment interface in a body of water near bridge piers and simr structures exposed to scour, is sensed and transformed by a frequency-modulated continuous wave method into an audio frequency signal that is related to the water/sediment interface elevation, which is transmitted by radio signal to a remote monitoring station. Radio signals received at the monitoring station are transmitted to a computer, which is programmed to compute the water/sediment interface elevation and to store such computed results for later use. A remote monitoring station may be equipped to monitor several water/sediment interface sensors.

Abstract: A towed array includes an array of N hydrophone groups and one or more nocoustic sensor modules structurally connected in-line with the array of hydrophone groups. The hydrophone groups and non-acoustic sensor module(s) are coupled to a common data transmission line. Each of the hydrophone groups defines a portion of an acoustic aperture occupying a specified length of the towed array. Each non-acoustic sensor module has a length that is n times the specified length where n is a whole number multiple of the total number of hydrophone groups.

Abstract: An apparatus for detecting and monitoring scouring around a structural mer uses time-domain reflectometry (TDR) to measure the level of sediment around the submerged portion of a structural member such as a bridge pier, dock, utility crossing, or similar structure. The apparatus includes an electrical pulse generator which transmits a series of electrical pulses, a sensor which is connected with the pulse generator, and a signal analyzer which receives and interprets the portion of the electrical pulses reflected back to the source from an interface, such as water/air or water/gravel, to calculate the position of the interface along the sensor. Knowledge of the position of the interfaces before and after a scouring event and of the dielectric constants of the surrounding media allows the user to detect and monitor the level of erosion caused by scouring.

Abstract: A method for performing mutations in a genetic algorithm-based underwater oustic contact tracking system includes the steps of: (i) providing an initially ordered list of bit numbers; (ii) selecting a random number from a uniform distribution of numbers; (iii) performing an inverse mapping of the selected random number via a binomial distribution, to determine a number of bits to mutate; (iv) determining if mutation is to be performed; (v) selecting particular bits to mutate; (vi) complementing selected bits; and (vii) outputting mutated contact state variables. The invention further contemplates a system for performing the above method.

Abstract: An underwater measurement device includes a housing for disposition on a bed surface, an opening defined by the housing, a buoy for disposition in the opening and buoyant so as to be floatable out of the opening, a cable interconnecting the housing and the buoy, and a winch in the buoy to pay out and take in the cable to permit the buoy to rise toward the sea surface and be drawn into the housing opening. A sensor is fixed to the buoy. Disposed in the device are communication circuitry for relaying to a remote station signals detected by the sensor, and operative circuitry for receiving instructions from the remote station and in response thereto operating the winch and the sensor.

Abstract: A fiber optic cable, coated to increase its sensitivity to acoustic press, is towed through a medium. The optical fiber contains Bragg grating sensors at regular intervals along its length. A steerable array of transducers sends a pulse of sound in the direction of the optical cable while broadband pulses of light are directed down the optical fiber. The pulses of light are selectively reflected back according to the spacing between the Bragg gratings. The sound pressure field causes a local strain in the fiber, thus changing the grating spacing. The sound velocity profile along the length of the optical cable is computed by measuring the amount of time necessary for successive Bragg gratings to respond to the acoustic pressure associated with the advancing wave front of the acoustic pulse.

Abstract: A buoyed sensor array communications system comprises multiple sensor syss electrically connected to a signal transmission line which are positioned at predetermined locations along the signal transmission line to form a linear sensor array. Each of the sensor systems generates a data signal in response to receiving an address signal. The system further includes; a processor system electrically connected to the signal transmission line for transmitting address signals to enable any one of the sensor systems at a time in a selectively accessed order and has a data storage memory for storing the data signal from each of the sensor systems as stored data. A radio frequency transmitting system is coupled to the data processor and transmits the stored data at a predetermined time. A negatively buoyant structure connected to the signal transmission line pulls the communications system to the bottom of a body of water upon deployment.