Abstract: A method for towing marine geophysical sensor streamers in a body of water includes moving a towing vessel at a selected speed along the surface of the body of water. At least one geophysical sensor streamer is towed by the vessel at a selected depth in the water. A velocity of the streamer in the water is measured at at least one position along the streamer. The selected speed of the towing vessel is adjusted if the measured velocity exceeds a selected threshold.

Abstract: An array of transducers for a sodar system, and the operation of the array in a monostatic sodar system. The array is made up of a number of individual sound transducers. Each transducer emits sound into the atmosphere and senses emitted sound that has been reflected by the atmosphere. The transducers have a generally circular cross-sectional shape. The transducers are arranged in a generally planar, generally hexagonal grid packing arrangement.

Abstract: An acoustic Doppler system comprising a plurality of acoustic transceivers, an acoustic subsystem controller and a main processing unit operatively connected to the acoustic subsystem controller. A first of the plurality of acoustic transceivers operates at a first acoustic frequency and is operatively connected to a first group of transducers producing an acoustic signal. A second of the plurality of acoustic transceivers operates at a second acoustic frequency and is operatively connected to a second group of transducers producing an acoustic signal. The first and second acoustic transceivers are adapted to operate concurrently at the first and second acoustic frequencies. The acoustic subsystem controller is operatively connected to the first and second acoustic transceivers and controls the acoustic signals produced by the first and second group of transducers.

Abstract: An AD2CP includes at least one transducer assembly emitting sets of slanted directional acoustic beams and receiving the echoes; and electronics that processes the echoes into depth cells and computes velocity in each depth cell. The AD2CP is configured so that each beam set has a profiling catenation, at least two of which are different, and the AD2CP is configured so that the emitting, receiving and processing operate contemporaneously.

Abstract: A system and a method for determining one or more wave characteristics from a moving platform are disclosed. A sonar system, such as an Acoustic Doppler Current Profiler, can profile the water motion relative to the platform, and an earth reference can determine a measure of the platform motion relative to a fixed earth reference. Both water profile and earth reference measurements can be synergistically employed to compensate for motion of the platform. Directional wave spectra and non-directional wave spectrum can be computed and translated via linear wave theory to surface height spectra and used to calculate characteristics, such as significant wave height, peak period, and peak direction.

Abstract: A system and method for measuring velocity in a fluid medium utilizing a transducer are disclosed. In one aspect, the method comprises transmitting an acoustic signal comprising N (where N is integer and N>1) pings for each of a plurality of beams, receiving echoes from each ping, obtaining a velocity estimate for each of the N pings based on echoes of the ping, and calculating a velocity based on the sum of the N velocity estimates such that the velocity is substantially free from error caused by cross-coupling between the beams.

Abstract: The present invention relates to a method for simultaneously determining the position and velocity of objects. Moreover the method comprising the steps of: 1) simultaneously generating a first signal for determining the velocity and a second signal for determining the position; 2) mixing the first signal with the second signal to form a mixed signal and subsequently transmitting the mixed signal towards an object using a transmitter, so that the mixed signal can be at least partially reflected by the object; and 4) evaluating an echo signal. Such a method may be used for various applications, such as monitoring blood vessel access and/or for pericardiocentesis, as well as for determining the blood flow velocity and the position of blood vessels.

Abstract: A method of detecting precipitation with a sodar apparatus that transmits sound beams into the atmosphere, detects echoes returned from the atmosphere, from the echoes determines a Doppler-shifted spectrum comprising the relative strength of the echoes at various Doppler-shifted frequencies, and estimates wind speed and direction. The method includes automatically estimating the presence of precipitation based on the Doppler-shifted spectrum.

Abstract: The invention relates to a method of determining an estimated speed of an aircraft relative to ground being overflown by the aircraft, in which use is made of the sum of an acceleration measurement of the aircraft plus a difference value, the difference value being obtained from observation data or signals relating to a region of the ground.

Abstract: A moving object detection apparatus comprises a transmitter, a receiver, a detection portion, a binary conversion portion and a judgment portion. The transmitter emits energy waves with a first frequency to a detection area. When receiving incoming energy waves from the detection area, the receiver generates an electric signal corresponding to the incoming energy waves. The detection portion obtains a detection signal from a reference signal with the first frequency and the electric signal. The binary conversion portion compares the detection signal with a conversion threshold signal to obtain a binary signal. The judgment portion judges whether or not a moving object approaching or leaving the receiver exists in the detection area based on the binary signal.

Abstract: A sensing device obtains range-related data—such as Doppler data or pulse time-of-flight data—from a sports projectile during flight. The time course of the range-related data is employed, in light of predictable characteristics of the projectile trajectory, to determine and output an accurate determination of the projectile speed for one or more points of interest in its flight. Such determination of speed may, for instance, be the speed at the time of projectile release, even though range-related data is gathered later in the flight, when the projectile is traveling neither so fast, nor straight at the sensor. Such sensing device may employ inexpensive short-range acoustic Doppler, and be incorporated into a target device that automatically displays to a pitcher-in-training the speed and ball/strike condition of each pitch.

Abstract: A system for determining the directional properties of surface waves or internal waves of a fluid medium includes a sonar system having a plurality of transducers for generating respective, separate acoustic beams and receiving echoes from one or more range cells located substantially within the beams; and a computer program for determining the directional properties associated with the surface waves or internal waves from the received echoes, wherein the computer program determines along-beam velocities along the separate acoustic beams and combines the along-beam velocities to form an equivalent orbital velocity vector. The system is mounted on or in a sub surface buoy that can move or rotate during measurement and includes a motion sensor measuring six degrees of freedom to account for horizontal velocity and vertical displacement in the subsurface buoy mounted sonar system.

Abstract: A method of measuring blood flow including several steps. In an initial step a first ultrasound beam is oriented in a direction substantially perpendicular to the direction of the blood flow to be measured. Next, the Doppler spectrum obtained from the backscattered echoes of said first ultrasound beam is measured. Subsequently, the ultrasound beam is reoriented so that the Doppler spectrum of the backscattered echoes of the ultrasound beam is substantially symmetrical around the zero frequency. The Doppler frequency of the backscattered echoes of a second ultrasound beam oriented at a fixed angle to the first ultrasound beam is then measured. Finally, the rate of blood flow is calculated based on the angle between the ultrasound beams and the measured Doppler frequency of the backscattered echoes of the second ultrasound beam.

Abstract: Systems and methods for positioning one or more spread elements of a marine seismic spread are described. One system comprises a seismic vessel-mounted acoustic Doppler current meter adapted to ascertain at least the horizontal component of the current velocity vector at a point ahead of the seismic vessel, and one or more controllers adapted to use the ascertained current velocity vector to control position of one or more seismic spread elements. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. This velocity, wave height, and pressure data is Fourier-transformed by one or more signal processors within the system, and a surface height spectrum produced. A cross-spectral coefficient matrix at each observed frequency is also generated from this data. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (MLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum.

Abstract: A system and method for measuring velocity in a fluid medium utilizing a phased array transducer are disclosed. The phased array transducer comprises a plurality of transducer elements arranged to form a single two-dimensional array. In one aspect, the method comprises receiving echoes of a plurality of beams generated by the transducer, calculating raw velocity estimates based at least in part on the echoes, and removing substantially a bias related to a first velocity from the raw velocity estimates. The first velocity is orthogonal to the face of the two-dimensional array.

Abstract: A system and method for measuring velocity in a fluid medium utilizing a measuring system are disclosed, wherein the measuring system comprises a transducer. In one aspect, the method comprises transmitting a first set of one or more signals of a bandwidth substantially broader than the bandwidth of the measuring system, receiving echoes from the first set of signals, obtaining a first velocity estimate based at least in part on the echoes from the first set of signals, transmitting a second set of one or more signals of a bandwidth, substantially equal to, or narrower than the bandwidth of the measuring system, receiving echoes from the second set of signals, obtaining two or more possible velocity estimates based at least in part on the echoes from the second set of signals, and selecting one of the possible velocity estimates based on the first velocity estimate.

Abstract: A method for determining the positions of targets by bistatic measurements using signals scattered by the targets is provided in which the velocities of the targets can also be determined. The range of the transmitters is selected so that a target at an arbitrary point can be measured, by scattering in the target, by at least four cooperating measuring facilities. First the targets are associated by calculating, in two independent ways, two sets of sums of distances between transmission points and targets and, respectively, targets and reception points. Subsequently, the two sums are sorted with respect to distance, compared with each other, and the sums that correspond with each other within a predetermined margin of error are stated to correspond to conceivable targets. The association of targets is improved and completed by corresponding calculations being carried out for Doppler velocities.

Abstract: A system and method of automatically controlling a terminal are disclosed. In one aspect, there is a method comprising: installing a sensing device in a terminal; and automatically controlling operations of the terminal when a certain object is detected by the sensing device within a predetermined range. According to certain aspects, a hard disk may be subjected to a full protection, power supplied to peripherals such as a keyboard or a mouse is saved. Furthermore, in other aspects, an automatic power-up/down operation to the terminal, automatic forward and backward operations of a browser and an automatic page-flipping operation of application software may be implemented. In another aspect, there is a control system for the terminal and the terminal equipped with such a control system.

Abstract: An AD2CP includes at least one transducer assembly emitting sets of slanted directional acoustic beams and receiving the echoes; and electronics that processes the echoes into depth cells and computes velocity in each depth cell. The AD2CP is configured so that each beam set has a profiling catenation, at least two of which are different, and the AD2CP is configured so that the emitting, receiving and processing operate contemporaneously.

Abstract: A method is provided for improving horizontal spatial resolution of a flow field in compact jet-like current features so as to quantify the axial velocity in the cross section of a compact jet using an Acoustic Doppler Current Profiler (ADCP). The ADCP is a four-beam, Janus-type ADCP having beams aligned so that each of the beams is at an angle of about 20° to 30° to vertical and at 45° to the fore and aft axis of the vessel, such that two beams point at 45° to forward and two pointing 45° to aft. The measurements from each range bin of the aft-facing beams are combined with the previously measured samples from the corresponding forward-facing beams at the same position along the vessel track.

Abstract: A system and method for measuring velocity in a fluid medium utilizing a measuring system are disclosed, wherein the measuring system comprises a transducer. In one aspect, the method comprises transmitting a first set of one or more signals of a bandwidth substantially broader than the bandwidth of the measuring system, receiving echoes from the first set of signals, obtaining a first velocity estimate based at least in part on the echoes from the first set of signals, transmitting a second set of one or more signals of a bandwidth, substantially equal to, or narrower than the bandwidth of the measuring system, receiving echoes from the second set of signals, obtaining two or more possible velocity estimates based at least in part on the echoes from the second set of signals, and selecting one of the possible velocity estimates based on the first velocity estimate.

Abstract: A system for determining the directional properties of surface waves or internal waves of a fluid medium includes a sonar system having a plurality of transducers for generating respective, separate acoustic beams and receiving echoes from one or more range cells located substantially within the beams; and a computer program executed by a processor for determining the directional properties associated with the surface waves or internal waves from the received echoes, wherein the computer program determines along-beam velocities along the separate acoustic beams and combines the along-beam velocities to form an equivalent orbital velocity vector.

Abstract: A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system is disclosed. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (MLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum. The frequency-specific spectra are combined to construct a complete two-dimensional wave directional spectrum.

Abstract: The present invention is directed to a method of allowing a computational load caused by the implementation of conventional signal processing methods operating by multicopy correlation, by simultaneous correlation of the spectrum of the received signal to copies of the signal, each of the copies having a different Doppler shift. The multicopy correlation operation is a time-frequency transformation of the received signal. Synthetic spectra are found by selection of spectral lines and concatenation, starting from the spectrum of the received signal. An inter-spectral product is computed, in other words by the product of each synthetic spectrum with the concatenated conjugate spectrum of the corresponding Doppler copy. A frequency-time transformation of the inter-spectral products is performed.

Abstract: A receiver includes a controller which receives A/D sampled input signals and shifts the sampled digital signal to compensate for Doppler effect in the input signal prior to demodulation. The controller compensates for a Doppler increased frequency by shifting the sampled digital signal so as to skip a sample period every n samples. This may be achieved by decreasing a cycle of m samples by one sample period every n samples. The controller compensates for a Doppler decreased frequency by shifting the sampled digital signal so as to add a sample period every n samples. This may be achieved by repeating a sample every n samples to shift the sampled digital signal. The compensation is performed in software on a multi-threaded processor.

Abstract: A method is provided for determining the position of an electronic device by receiving a code modulated signal transmitted by satellites, and position information of the satellites and time data, and by generating local time data. In the method, delta range measurements are taken for at least four different satellites. For each of said at least four satellites, the velocity of the satellite is determined in relation to the positioning receiver. Furthermore, in the method, the delta range measurement results are replaced in an algorithm applying said delta range measurements and velocities to generate reference data for determining the local time data frequency error and the position. The local time data frequency error and the position are determined by searching for the minimum value of said reference data. A system and an electronic device applying the method are also provided.

Abstract: A time domain communications system wherein a broadband of time-spaced signals, essentially monocycle-like signals, are derived from applying stepped-in-amplitude signals to a broadband antenna, in this case, a reverse bicone antenna. When received, the thus transmitted signals are multiplied by a D.C. replica of each transmitted signal, and thereafter, they are, successively, short time and long time integrated to achieve detection.

Abstract: Apparatus for Doppler correction in a wireless communications system, including a first frequency synthesizer for generating a carrier signal oscillating at a rate responsive to a first input, a counter coupled to the first input for generating a Doppler compensation signal, the counter having a clock input, and a second frequency synthesizer coupled to the clock input for generating a clock signal oscillating at a rate responsive to a rate input. The rate input is adjusted over time according to a predetermined sequence so that the Doppler compensation signal compensates for the Doppler effect experienced by, for example, ground-to-satellite communications in a satellite communications system.

Abstract: An ultrasound wave is transmitted from a probe (120) to a moving reflector (130) and the reflected ultrasound wave is received back by the same probe (120). With n-divided wave bands of the to-be-used spectrum, the ultrasound wave to be transmitted is made up of up chirp signals and down chirp signals from n number of down chirp signal generators (112, 113) and up chirp signal generators (116, 117), creating complementary multiplexed chirp signals through synthesizers (114, 118). Cross-correlation is taken by a correlator between the reception signal received at the probe (120) and the up chirp and the down chirp signals, respectively, so as to provide compressed up and down signals and then combining the obtained compressed signals through synthesizers (144, 148). Doppler measurement is performed by determining the correlation distance through taking the cross-correlation between these compressed signals by a cross-correlator (160) and performing envelope detection by an envelope detector (170).

Abstract: The present invention relates to a system for using signals scattered by targets to determine position and velocity for each of the targets and comprises a set of transmitters and receivers of electromagnetic or acoustic signals, said transmitters and receivers dispersed to known points. Each pair of transmitter and receiver, monostatic or bistatic, is named a measuring facility. The ranges of the transmitters are chosen so that a target at an arbitrary point within the position space can be measured via scattering in the target by at least four measuring facilities. For each measuring facility, target detection occurs with constant false alarm rate in the form of probabilities over resolution cells with regards to range and Doppler velocity and conceivable targets are placed in a 2-dimensional linear space belonging to the measuring facility.

Abstract: A system and method for measuring water currents is disclosed in which an oceanographer can profile and display the water currents for an entire water column in real time. The profile is used in monitoring ocean currents that may pose a risk to the drilling riser or its contents. An ADCP is attached to a remotely operated vehicle (ROV) and transmits data to a computer system to be processed and displayed in real time. The method comprises receiving ADCP and ROV data, monitoring the heading of the current profiler, correcting and processing the data, and outputting a profile of the currents through a water column.

Abstract: A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. This velocity, wave height, and pressure data is Fourier-transformed by one or more signal processors within the system, and a surface height spectrum produced. A cross-spectral coefficient matrix at each observed frequency is also generated from this data. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (MLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum.

Abstract: A transmitted signal and a received signal are combined and the combination is expected to determine whether or not a target signal is present. Either the transmitted signal or the received signal is combined with an auxiliary signal containing a range of frequencies corresponding to an anticipated Doppler shift, so that an output of the combined transmitted and received signal will be present only if a target signal exhibiting a Doppler shift within the anticipated range is present. The auxiliary signal preferably comprises finite-duration signal portions of different types so as to provide a substantially uniform frequency response throughout the selected range.

Abstract: An improved acoustic Doppler flow measurement system which employs multiple acoustic frequencies to acquire multiple independent backscatter data from the flow channel, combining the data to enable survey measurement of channel flow properties beyond what can be achieved with either a single frequency system or multiple independent single frequency systems. The system is installed on small moving channel survey boats, remotely measuring vertical profiles of river currents, achieving accurate surveys of channel flow velocity structure and bottom topography, enabling accurate (approximately 1% resolution) survey measurement of channel flow discharge. Significant synergistic improvements are realized from both physical and functional integrations of the multi-frequency operational capability into a single integrated flow survey system. Use of phased array transducer techniques further reduces flow disturbance and transducer size, enabling use on even smaller survey boats.

Abstract: Provided is a system that allows navigation by GPS while underwater by locating the antenna above water and the display below water. In one embodiment, the GPS antenna is attached to a tow-able buoy having a diver-down flag. In another embodiment, the GPS antenna is carried by the diver and released to float to the surface when the diver wishes to navigate. A preferred embodiment uses a handheld computer to display GPS data, and can be expanded to also calculate and display depth and decompression data, and to provide for further expansion and integration to include other devices.

Abstract: A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. This velocity, wave height, and pressure data is Fourier-transformed by one or more signal processors within the system, and a surface height spectrum produced. A cross-spectral coefficient matrix at each observed frequency is also generated from this data. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (MLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum.

Abstract: An ultrasonic moving-speed measuring system comprises a piezoelectric substrate, a thickness-vibration mode transducer, an interdigital transducer, and a signal analyzer. The piezoelectric substrate, the thickness-vibration mode transducer, and the interdigital transducer form a transducing assembly. When an input electric signal with a carrier frequency is applied to the thickness-vibration mode transducer, a longitudinal wave is radiated into a medium that is in touch with the bottom of the transducing assembly. If the longitudinal wave is reflected at a material in the medium, a delayed electric signal with a Doppler frequency is detected at the interdigital transducer via a mode conversion from a reflected longitudinal wave to a leaky Lamb wave. The moving speed of the material is sensed at the signal analyzer in terms of a difference between the carrier- and Doppler frequencies.

Abstract: Doppler shift compensation by interpolation of a new sample between successively received signal samples using stored values of an interpolation function. The interpolation function has a non-zero amplitude in an argument range symmetrical about zero argument and zero amplitude outside the range. The time location of a new sample is shifted relative to a pair of received signal samples by an amount corresponding to a Doppler shift. The amplitude of the new sample is computed at a new sample index by combining the pair of received signal samples with corresponding samples of the interpolation function, each corresponding sample of the interpolation function being that sample whose argument is a difference between a corresponding one of the first and second indices and the new sample index. Due to the symmetry properties of the interpolation function, this operation requires as little as two multiply operations and one add operation for each new sample.

Abstract: An ultrasound transducer is coupled to a transmitter having a source of ultrasound signal. A receiving ultrasound transducer is coupled to a preamplifier and mixer. The mixer is further coupled to a demodulator and filter which in turn is coupled to an amplifier and a comparator. The comparator output is coupled to a controller which performs edge detection of the comparator output signal. The transmitter produces ultrasound energy which is reflected from an object to the receiving transducer. The shift in frequency between the transmitted ultrasound energy and the reflected ultrasound energy is used to determine the speed of the object by employing doppler effect. Frequency detection is enhanced by mixing the transmitted and reflected ultrasound signals to provide a beat frequency signal.

Abstract: A device for non-contractual measurement of the speed of an object moving over a surface comprises a means for radiating a signal of fixed frequency at an angle onto the surface in or against the direction of motion, said angle being variable by the movement of the object, and for receiving a Doppler-shifted signal reflected at the surface. A means is provided for combining a plurality of reflected Doppler-shifted signals, which are received in temporal succession, so as to produce a combined spectrum. The device for non-contractual speed measurement additionally comprises a means for detecting from the combined spectrum the spectral portion having the highest or lowest frequency and exceeding a predetermined signal power, and a means for deducing the speed from the frequency of the detected spectral portion.

Abstract: A method for determining the velocity of features such as wind. The method preferably includes producing sensor signals and projecting the sensor signals sequentially along lines lying on the surface of a cone. The sensor signals may be in the form of lidar, radar or sonar for example. As the sensor signals are transmitted, the signals contact objects and are backscattered. The backscattered sensor signals are received to determine the location of objects as they pass through the transmission path. The speed and direction the object is moving may be calculated using the backscattered data. The data may be plotted in a two dimensional array with a scan angle on one axis and a scan time on the other axis. The prominent curves that appear in the plot may be analyzed to determine the speed and direction the object is traveling.

Abstract: A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. This velocity, wave height, and pressure data is Fourier-transformed by one or more signal processors within the system, and a surface height spectrum produced. A cross-spectral coefficient matrix at each observed frequency is also generated from this data. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (NLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum.

Abstract: The invention is a system for measuring the rate of food pellet loss in a fish farming operation. The fish are held in a seacage in a body of water. Food dropped into the seacage sinks down through the cage and uneaten pellets exit the bottom of the seacage. An echo transducer below the cage generates an echo pattern that is converted into pellet loss data.

Abstract: A process for making it possible to detect moving objects by an active sonar operating by the Dopper effect. The process uses, as a transmission signal, a burst of N pulses encoded so as to present a spectrum having a comb-of-lines structure. In this way, the “signal/reverberation” ratio of the useful signal intensity to the reverberated intensity is increased, thereby increasing the efficiency of the sonar. The process allows objects moving in a reverberating transmission medium to be detected more easily.

Abstract: A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. This velocity, wave height, and pressure data is Fourier-transformed by one or more signal processors within the system, and a surface height spectrum produced. A cross-spectral coefficient matrix at each observed frequency is also generated from this data. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (MLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum.

Abstract: A speed measuring apparatus including a transmitter for transmitting an acoustic reference wave toward a moving-target, the acoustic reference wave being generated based on a reference signal with a predetermined frequency. Also included is a receiver for receiving acoustic reflection waves which are generated by the transmitted acoustic reference wave being reflected by the moving-target, for converting the acoustic reflection waves to receiver signals, and for outputting the receiver signals therefrom. Further, a signal attenuating unit for selectively attenuating a signal component with the same frequency as the frequency of the reference signal in the receiver signals which are output from the receiver and outputting signals therefrom and a band pass filter unit for selecting at least one Doppler signal component from the signals output from the signal attenuating unit are included.

Abstract: This invention describes a new method to estimate the sediment flux in front of a Coherent Acoustic Sediment Probe (CASP) instrument. Also, described is a newly invented Bistatic Doppler Velocity and Sediment Profiler (BDVSP) device for measuring sediment concentration, sediment velocity, and the resultant sediment transport in a sediment bed, and for the measurement of turbulent stresses and dissipation in the ocean.

Abstract: A method and system are provided to estimate a ship's velocity. Two ship sonar returns from two different directions are selected. Each return includes volume reverberation data and bottom reverberation data. Doppler shift for each of the two returns based on the volume reverberation data is determined as a basis for estimating ship velocity relative to the water. Doppler shift for each of the two returns based on the bottom reverberation data is determined as a basis for estimating ship velocity relative to the ground.

Abstract: A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. This velocity, wave height, and pressure data is Fourier-transformed by one or more signal processors within the system, and a surface height spectrum produced. A cross-spectral coefficient matrix at each observed frequency is also generated from this data. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (MLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum.