Abstract: Sodar systems and methods for acoustically sounding air are disclosed in which chirps longer than 300 ms—and preferably with durations of tens of seconds—are used along with matched filter and/or Fourier processing methods to derive phase signals indicative of air characteristics in range. A listen-while-transmit strategy is preferred, the direct signal being removed by subtracting the phase signals from two or more receivers located near the transmitter so as to be in the same noise environment. The resultant differential signals can be related to cross-range wind with range distance. In one example, apparatus (100) is employed comprising a reflector dish (102) over which one central loudspeaker (110) and four microphones (112, 114, 130 and 132) are mounted, the microphones preferably being located on cardinal compass points and having their axes (124, 126) slightly angled with respect to the vertical transmission axis (122).

Abstract: A temporal correlation SONAR calculates the velocity and position of a water navigable craft. A first pulse and a second set of pulses are transmitted towards an ocean bottom. A tetrad of hydrophones on the craft receives echoes of the pulses. A correlation between the first pulse received on one hydrophone with the second pulses received on another hydrophone produces correlation points, for which a correlogram is generated. The distance between the hydrophones is divided by twice the time value at the peak of the correlation to calculate the velocity of the vessel. Another correlation is generated for hydrophones pairs that are positioned diagonally from one another, and maximum correlation values, along with hydrophone angles, are used to calculate athwart-ship velocity.

Abstract: The invention relates to a method for determining ocean current using geophysical data acqusition means which are on board a ship, said ship towing at least one streamer which is equipped with at least one traction sensor and position measuring means. The invention is characterised in that it comprises the following steps, consisting in: collecting the measurements from said traction sensor, collecting the measurements from said position measuring means, repeatedly calculating a current vector that is representative of the real current by repeating the following operations using a given sampling time step: calculating simulated traction and streamer positioning data for numerous simulation input current vectors, comparing the simulated data to real measurements taken by said traction and position measuring means for each simulation input current vector. The invention also relates to a device used to carry out one such method.

Abstract: The invention relates to an arrangement for measuring the speed of sound, the arrangement comprising: an electrical pulse generating means (402) for generating an output electrical pulse signal (404), a transmitting transducer (403) for converting said output electrical pulse signal (404) into an output acoustic pulse signal (405), a reflector (407) for reflecting said output acoustic pulse signal (405), thereby producing a reflected acoustic pulse signal (409), a receiving transducer (408) being arranged such as to receive said output acoustic pulse signal (405) transmitted directly from said transmitting transducer and said reflected acoustic pulse signal (409) reflected by said reflector, wherein said receiving transducer converts the received output acoustic pulse signal (405) into a reconstructed output electrical pulse signal (410) and the reflected acoustic pulse signal (409) into a reconstructed reflected electrical pulse signal (411), a speed determination means for determining the speed of sound (41

Abstract: The two-dimensional velocity vector using a pulsed ultrasound field can be determined with the invention. The method uses a focused ultrasound field along the velocity direction for probing the moving medium under investigation. Several pulses are emitted and the focused received fields along the velocity direction are cross-correlated. The time shift between received signals is found from the peak in the cross-correlation function and the velocity is thereby determined.

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: A time difference between two similar but time-shifted signals is determined using a difference function. For example, similar but time-shifted first and second signals are sampled to generate a discrete mathematical function whose discrete sample points define overlapping ranges. Typically, at least one of the multiple overlapping ranges defined by sample points of the discrete mathematical function can be used to interpolate a time difference between the first and second signals.

Abstract: A relative speed of an object is determined by monitoring random reflective surfaces in water. The system includes a first and second transmitter-receiver pair for producing echo signals of a monitored region. The monitoring pair of transducers are preferably positioned along an axis of motion of the object such that sampled data from the first and second transmitter-receiver pair are substantially similar but shifted in time due to a separation of transducers. Echo signal data from the transducers are then used to generate a time difference correlation function that is used to determine a time difference between the first and second signals. Based on the time difference between the time-shifted echo signals, a speed of a vessel is determined.

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 system and method for determining a sound speed profile of a water column. A free falling sound source is deployed in the water at a known location and time. The sound source transmits acoustic pulses omnidirectionally therefrom at predetermined times after deployment. An acoustic receiver located at a known location detects each acoustic pulse. The time differential between each predetermined time and a time of arrival for each subsequent acoustic pulse is determined. Speed of sound for each portion of the water column is then determined as a function of the time differential, the known locations of sound source deployment and the acoustic receiver, and the known rate of descent of the sound source. The sound source can be constructed from a hydrodynamic body housing a power source, timing electronics, and spark gap electrodes. A bubble, generated by the spark gap electrodes, implodes to create the acoustic pulse.

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 time difference between two similar but time-shifted signals is determined using a difference function. For example, similar but time-shifted first and second signals are sampled to generate a discrete mathematical function whose discrete sample points define overlapping ranges. Typically, at least one of the multiple overlapping ranges defined by sample points of the discrete mathematical function can be used to interpolate a time difference between the first and second signals.

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: A relative speed of an object is determined by monitoring random reflective surfaces in water. The system includes a first and second transmitter-receiver pair for producing echo signals of a monitored region. The monitoring pair of transducers are preferably positioned along an axis of motion of the object such that sampled data from the first and second transmitter-receiver pair are substantially similar but shifted in time due to a separation of transducers. Echo signal data from the transducers are then used to generate a time difference correlation function that is used to determine a time difference between the first and second signals. Based on the time difference between the time-shifted echo signals, a speed of a vessel is determined.

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 relative speed of an object is determined by monitoring random reflective surfaces in water. The system includes a first and second transmitter-receiver pair for producing echo signals of a monitored region. The monitoring pair of transducers are preferably positioned along an axis of motion of the object such that sampled data from the first and second transmitter-receiver pair are substantially similar but shifted in time due to a separation of transducers. Echo signal data from the transducers are then used to generate a time difference correlation function that is used to determine a time difference between the first and second signals. Based on the time difference between the time-shifted echo signals, a speed of a vessel is determined.

Abstract: The invention relates to a device for measuring the fluid consumption of a user over a given measurement time, including a volumetric meter (26) connected to a central information processing unit (28). This unit is designed to take a series of readings at successive intervals in said measurement time, so as to compare each reading with a reference value that corresponds to a predetermined nominal consumption threshold and thus from this deduce the quantity consumed over said measurement time corresponding to consumption with a flow rate higher than the nominal consumption threshold.

Abstract: A method and system for determining the effective sound velocity between a source of sound energy located at an initial depth ZS and an actual target located at another depth. A system utilizing a device such as a computer or microprocessor is used for implementing the method of the present invention. An effective sound velocity (“ESV”) matrix is generated wherein ESV values are a function of actual target depth and actual target elevation angle. The ESV matrix is then used to determine the ESV between a source of sound energy located at an initial depth ZS and an actual target located at any depth between ZS and a final target depth ZT.

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 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: The proposed velocity-measuring device (1) can measure the velocity of a wide range of objects via simple sound waves utilising the Doppler-effect principle. The velocity-measuring device (1) consists of a base unit (10) with a command-display unit (17). The base unit (10) holds a sound wave emitter with no less than one loudspeaker (8), a sound wave receiver with no less than one microphone (9), a computing unit and a display screen. In order to measure velocities the device (1) shall be placed next to the projected object line of movement in such a way that the sound waves and the line of movement meet at an acute or obtuse angle. The sound waves striking the followed object shall be partially reflected and subsequently received by the microphone (9) of the receiver. The difference between the emitting frequency and the echo frequency shall be analysed within the computing unit, producing the object velocity. The calculated velocity shall be shown via the control-display unit (17).

Abstract: An ultrasonic ranging system and method for detecting the presence of and distance to a target using ultrasonic sound waves generated by an ultrasonic transducer with reduced audible noise. Electrical ultrasonic signal pulses are modulated according to a smooth modulation envelope and a transducer drive signal is generated from the modulated signal pulses. The transducer drive signal drives an ultrasonic transducer which generates ultrasonic sound waves for transmission in a desired path, and further receives ultrasonic sound waves reflected from targets in the transmission path. The received ultrasonic sound waves are converted to an electrical signal that is processed by a processor to provide time and distance information to the target. The distance information is computed by using a middle time value for the transmitted and received signals.

Abstract: According to the present invention, a method and apparatus rely upon tomographic measurement of the speed of sound and fluid velocity in a pipe. The invention provides a more accurate profile of velocity within flow fields where the speed of sound varies within the cross-section of the pipe. This profile is obtained by reconstruction of the velocity profile from the local speed of sound measurement simultaneously with the flow velocity. The method of the present invention is real-time tomographic ultrasonic Doppler velocimetry utilizing a to plurality of ultrasonic transmission and reflection measurements along two orthogonal sets of parallel acoustic lines-of-sight. The fluid velocity profile and the acoustic velocity profile are determined by iteration between determining a fluid velocity profile and measuring local acoustic velocity until convergence is reached.

Abstract: The invention relates to a portable simulator for bathymetric probes of the thermometric or calorimetric types connected at the output to an acquisition card. The simulator has at least four circuits corresponding, respectively, to the following four functions: a) selecting a probe type (thermometric or celerimetric) and establishing a firing sequence; b) generating a periodic signal of variable frequency to simulate a celerimetric type probe; c) generating a variation in temperature to simulate a thermometric probe; d) detecting a supply voltage threshold, with circuits b and c having a common section ending at the input of the acquisition card.

Abstract: A method and a device for detecting fodder waste/loss within a fish enclosure (1), where a sound transmitter (4) and a hydrophone (6) are disposed as an upwardly directed echo sounder close to the bottom of the enclosure (1). Sound echoes from objects situated above the sound transmitter (4), are picked up by the hydrophone (6). A measuring unit (8) separates signals from the hydrophone (6) into various frequency bands close to the transmitted sound frequency. The distance and amount of the objects are determined in a way similar to the one used in echo sounders. Sinking objects will cause rejected sounds having frequencies slightly higher than the transmitted frequency, so called Doppler effect, and the frequency difference is a measure of the sinking speed of the object.

Abstract: The present invention, generally speaking, provides an acoustic railway crossing detector. The present invention provides a means of not only detecting the presence of a train, but it can determine speed and direction of travel. This allows a more adaptive control of the railway crossing gates and may reduce the nuisance factor of having the gate close too far in advance of the train reaching the crossing. It is also much less susceptible to false activation by natural causes or acts of vandalism. In accordance with one embodiment of the invention, an acoustic railway crossing detector includes at least one acoustic emitter; at least one acoustic detector; multiple reflectors arranged to reflect acoustic energy produced by an acoustic emitter toward an acoustic detector, and control circuitry coupled to an acoustic detector for producing an indication of whether or not a train is present.

Abstract: A speed sensor for a ship, more particularly, a thin speed sensor which can be mounted in the hull of the ship and remain flush with the outer surface of the hull. The transducer assembly for the speed sensor is composed of two thin piezoelectric transducers mounted in a spacer plate that locates them in an exact position relative to each other. A baseplate and a coverplate are affixed by appropriate adhesive techniques to each side of the transducers to create a single transducer assembly. Holes through the baseplate and spacer plate permit electrical contact to each side of the transducers so that they may be stimulated to generate acoustic waves. The entire transducer assembly is significantly thinner than the hulls of most watercraft. Thus, a large hole completely through the hull is not necessary. Rather, a shallow recess approximately equal to the thickness of the transducer assembly is made in the hull to countersink the transducer assembly flush with the hull.

Abstract: A phase locked loop circuit having a voltage controlled oscillator for generating a clock signal with a frequency determined by a voltage control signal supplied to the voltage controlled oscillator, an AD-conversion circuit for sampling a target signal with a timing determined by the clock signal and for converting sampled values into digital data, a phase locked loop control circuit for generating control data with values representing values of the digital data, and a DA-conversion circuit having an adjustable conversion characteristic for converting the control data into an analog signal and for outputting the analog signal to the voltage controlled oscillator as the voltage control signal.

Abstract: A velocity measurement apparatus is disclosed which is composed of a transmitter having a plurality of elements for transmitting a signal wave, a receiver having a plurality of elements for receiving a reflected signal from a target object, and a Fourier transformation processor for two-dimensionally Fourier transforming a two-dimensional received signal in an array direction and a time axial direction of the plurality of elements of the receiver. The two-dimensional received signal is derived by repeating the transmission and reception operations a plurality of times. The velocity measurement apparatus measures a moving velocity of the target object directing to the means for receiving.

Abstract: A speed sensor for a ship, more particularly, a thin speed sensor which can be mounted in the hull of the ship and remain flush with the outer surface of the hull. The transducer assembly for the speed sensor is composed of two thin piezoelectric transducers mounted in a spacer plate that locates them in an exact position relative to each other. A baseplate and a coverplate are affixed by appropriate adhesive techniques to each side of the transducers to create a single transducer assembly. Holes through the baseplate and spacer plate permit electrical contact to each side of the transducers so that they may be stimulated to generate acoustic waves. The entire transducer assembly is significantly thinner than the hulls of most watercraft. Thus, a large hole completely through the hull is not necessary. Rather, a shallow recess approximately equal to the thickness of the transducer assembly is made in the hull to countersink the transducer assembly flush with the hull.

Abstract: A traffic monitoring system includes many monitoring nodes (10) distributed along many roads. A sonar ranging module (12) in each node continually measures the height of vehicles (19) crossing thereunder with repeated sonar pulses. A microcontroller (14) contains suitable instructions for estimating the speed of the vehicle by assigning a length to the vehicle based on its measured height, and dividing the length by the crossing time that the vehicle took to cross under the sonar module. The speed information from each node is transmitted to a central station (11) via a communication link (17). In a second embodiment, each node (10A) includes a pair of sonar modules (12A) spaced apart along a road. These measures the height of the vehicle, as well as the traversal time it takes to travel between both sonar modules. The microcontroller (14A) contains suitable instructions for dividing the modules' separation distance by the traversal time to accurately calculate the speed of the vehicle.

Abstract: A method of remotely determining the three-dimensional velocity of a fluid such as air or water, the method consisting in emitting signals of determined frequencies in at least three different directions by means of a plane array of transducers, and in using said transducers to pick up acoustic signals backscattered by the fluid, the method consisting in emitting trains of signals at different determined frequencies f1, f2, and f3, firstly in a determined direction D1, then in a determined direction D2, and finally in a determined direction D3, and subsequently in picking up all of the signals backscattered by the fluid. The invention makes it possible to improve the accuracy and to increase the maximum range of measurements.

Abstract: An improved method of measuring the flow velocity of water bodies, characterized in that, in addition to a principal direct path along which acoustic signals are propagated across and through the direction of flow of water, an auxiliary indirect path for acoustic signals is utilized comprising two segments of an acoustic signal reflected at a water-air or water-ice boundary of said body of water.

Abstract: A distance-velocity predicting system has an illuminator for projecting a light beam for searching for an obstacle, and a plurality of position sensors spaced at a distance corresponding to a base line length. A minimum value of a distance component from the base line to an obstacle lying in a direction perpendicular to the base line, which is obtained from the light beam and the position sensors, or a value in the neighborhood of the minimum value, is sampled to obtain time-series data, and a relative velocity component in a direction perpendicular to the base line with respect to the obstacle is obtained in real time by using the time-series data. The relative velocity component perpendicular to the base line is compared with a predetermined threshold value, and when the relative velocity component exceeds the threshold value, a starting signal for life protecting equipment is generated.

Abstract: A system and method for measuring current velocities using coded-pulse broadband acoustic signals. Autocorrelation of two phase coded pulses which are in the water during a single transmission cycle is used to calculate a Doppler frequency. The effective result is current profilers having improved profiling range and spatio-temporal resolution.

Abstract: Frequency-modulated wave trains are used in target locating by means of transmitted pulses and evaluation of portions reflected by the target in relation to bearing, distance and speed, wherein the pulse length and bandwidth of the transmitted pulse are pre-selected. The received signals are evaluated in Doppler channels by calculation of the ambiguity function. To make possible an increase in accuracy of the speed determination with the same number of Doppler channels, the frequency of the wave train within the bandwidth is calculated in accordance with an irrational function, the exponent of which has a value between 0 and 1. The smaller the value, while keeping the same pulse length, the greater the Doppler sensitivity. This method for modulating the wave train in the transmitted pulse can be advantageously employed for target identification by means of sound waves and electromagnetic waves.

Abstract: In a correlation device, a system and method for measuring velocities using a single coded pulse generator. The correlation device may also include maximum likelihood estimation techniques for processing the echo signals received from a plurality of transducers. The presently preferred embodiment of the device is as a current profiler having a bottom tracking capability for providing vessel velocity.

Abstract: A first projector that generates a beam of acoustic energy having a first equency, and a second acoustic projector that generates a beam of acoustic energy having a second frequency are provided. Interaction between the intersecting beams and particles present in the aquatic environment cause radiation of a third frequency at the region of beam intersection. The third frequency acoustic waves returned from the non-linear acoustic radiating area are monitored at a hydrophone, and the travel time of sound from the projectors to the hydrophone is determined. Successive readings can be made at various depths to obtain a velocity profile. Velocimetry can thus be accomplished free from any need to lower a tethered physical velocimeter into the depths.

Abstract: The present invention relates to a method of resolving an ambiguity in the stimation of vertical velocity of a moving underwater or surface vehicle. Three acoustic pulses are successively transmitted. They are received by a series of detectors located on the vehicle. The time difference between correlated first and second received pulses is measured. The time different between correlated first and third received pulses is also measured. The phase shifts between the three transmitted pulses and three received pulses is measured. This information is used to determine the vertical velocity of the vehicle.

Abstract: An apparatus and method for determining the velocity of sound propagation a fluid as a function of position in the fluid along an axis. A wave of acoustic energy is transmitted along the axis to produce a disturbance that moves in the medium at the velocity of sound. A laser generator transmits a light pulse substantially along the axis through the fluid medium. As the light passes through the disturbance, light backscatters in a characteristic pattern that a detector senses for analysis to provide information concerning the distance traveled and the time of travel for the acoustic wave through the fluid medium and to provide a profile of output characteristic, such as the speed of sound in the medium, as a function of position in the medium.

Abstract: An apparatus for measuring velocity relative to a reference plane having a linear sonar array disposed in parallel with the direction of travel and including from the foremost position to the rearmost position a first transmitter, a plurality of first receivers, a second transmitter, and a plurality of second receivers. The second transmitter is controlled to transmit a sonar pulse after a predetermined time delay has lapsed since the first transmitter transmitted a sonar pulse. The predetermined time delay is selected such that the second transmitter transmits the sonar pulse when the second transmitter occupies the position which the first transmitter occupied when it transmitted the first sonar pulse.

Abstract: In a correlation device, a system and method for measuring velocities using a single coded pulse generator. The correlation device may also include maximum likelihood estimation techniques for processing the echo signals received from a plurality of transducers. The presently preferred embodiment of the device is as a current profiler having a bottom tracking capability for providing vessel velocity.

Abstract: Apparatus and method for determining the condition of the floor to be cleaned by a cleaning robot. The apparatus comprises an ultrasonic wave signal transmitting circuit for transmitting an ultrasonic wave signal to an ultrasonic wave signal transmitter under the control of a microcomputer, a receiving amplifying unit for amplifying the ultrasonic wave signal transmitted from the ultrasonic wave signal transmitter and received in a ultrasonic wave signal receiver, a receiving demodulating unit for smoothing the output signal from the receiving amplifying unit to demodulate it and then apply it to the microcomputer. According to the control of the microcomputer, the ultrasonic wave signal is transmitted for a predetermined period. The period from the time when the ultrasonic wave signal is transmitted to the time when the ultrasonic wave signal is received in the ultrasonic wave signal receiver is measured.

Abstract: A system for measuring the speed in water of an underwater towed array has towbody connected in close proximity to the array by means of a rope drogue. The towbody has a freely turning propeller that turns a shaft that has a rotor magnet. Magnetic pulses from the rotor magnet are converted first to an electrical and then to an acoustical signal. The acoustical signal from the towbody is received by the towed array and converted back to an electrical signal that is transmitted along a line to a ship that is towing the array. The ship then displays the detected speed and/or utilizes the information received for control purposes.

Abstract: A system and method for bottom tracking in a sonar system. The present invention provides for convolving the received signal with the second derivative, or an approximation thereof, of the matched transmitted pulse. In another aspect of the invention, the received signal is convolved with the matching transmitter pulse and the result is evaluated by summing the differences between a central peak and its neighboring left and right values. The filtering of the present invention removes the effect of water absorption on signal amplitude. The invention also includes compensating for spreading loss in the received signal.

Abstract: An ultrasonic rotational speed sensor in which all of the various electronic devices of the sensor are arranged compactly on one side of a rotational member to be measured, while maintaining a high precision in a rotational speed measurement. In this sensor, the transmitter microphone and the receiver microphone as well as other electronic devices associated with them are arranged on the same one side of the rotational member, where the rotational speed of the rotational member is determined from a period of the ultrasonic signals transmitted from the transmitter microphone, reflected at non-notch portions of the rotational member, and received by the receiving microphone, while a direct transmission from the transmitter microphone to the receiver microphone without an interaction with the rotational member is prevented by the use of a high frequency ultrasonic signals at MHz level.

Abstract: An acoustic log for vessels includes a transmitter which sends a signal within a lobe region and at least two receivers provided for receiving signals reflected from a reference for determining the velocity component of a vessel relative to the reference in the measuring direction determined by the two receivers. The log further includes a transducer device with five crystals serving as transmitter and receiver elements for transmitting and receiving acoustic signals, and being arranged such that combinations in pairs of the crystals define twelve measuring directions regularly distributed around revolution.

Abstract: A technique for obtaining a class of beam patterns is described which results in eliminating the Doppler spread effect of the mean transverse component of flow of scatterers. This is accomplished by weighting various array elements. This component of flow is typically the main contributor to Doppler frequency spread. With this component eliminated, the other contributor of Doppler spread is due to the turbulent or fluctuating scatterer motion on the scale of the scattering volume. This contributor is smaller of the two and is estimated by standard Doppler methods.

Abstract: A gain-controlled amplifier (24) in a sonic flow meter accepts an output signal from each transducer of a plurality of pairs of transducers (1a, 1b; 2a, 2b; 3a, 3b; and 4a, 4b) in sequence. A ramp generator (62) generates a time-varying-gain output, which increases between the transmission of a pulse by one transducer and the reception thereof by another. This time-varying-gain signal is one component of the amplifier's gain-control signal, which includes as another component an AGC value fetched from a memory (50) and rendered into analog form by a digital-to-analog converter (42). The value in the memory (50) is the difference between the time-varying-gain value and the value that other circuitry (30, 36) has determined to be necessary by monitoring the amplifier output produced during a previous operation of the same transducer pair.

Abstract: A speed meter measures low range speeds such as feed speeds on a machining devices. Ultrasonic waves are radiated against a mobile object performing a linear displacement with respect to a detection head, and ultrasonic waves reflected by the mobile object are used for controlling the state of a pair of signal gating elements. Clock pulses passed to the elements are gated over different periods phased from each other by an operation interval which can be adjusted depending on the process conditions. Distances between the detection head and the mobile object in the different periods are specified by count values obtained from the results of respective gating, and the average speed of the linear displacement of the mobile object is calculated on the basis of these count values. Digital mode processing of the signals simplifies the construction and lowers the production cost.