Abstract: This disclosure relates to a system and method for measuring average temperature of mixed fluid in an enclosed chamber. Measurement is based on two independent principle as measuring variation in acoustic wave velocity and variation in resistivity that works on a single setup. First principle is based on measuring acoustic wave velocity in a known medium, which is isolated from the surrounding. The system comprises a primary pipe and a secondary pipe, wherein the ends of the pipes reside inside the enclosed chamber. The primary pipe is made out of good conductor of heat and filled with air. Ends of the primary pipe is fitted with a transducers have one transmitter at one end and one receiver at another end. Average temperature of the mixed fluid is measured based on the variations in sound velocity of acoustic wave passed through the primary pipe and resistivity variations of the primary pipe.

Abstract: A method and apparatus for determining a pressure in an annulus between an inner casing and an outer casing. An acoustic transducer is disposed within the casing at a selected depth within the inner casing and is configured to generate an acoustic pulse and receive a reflection of the acoustic pulse from the inner casing. A time of flight is measured of the acoustic pulse to the inner surface of the inner casing. An inner diameter of the inner casing is determined from the time of flight. The pressure in the annulus is determined from the inner diameter. A processor can be used to measure time and determine inner diameter and annulus pressure.

Abstract: A device for examining a test material via acoustic spectroscopy, including a measuring distance which is formed from a reference material and the test material an ultrasonic transmission device for transmitting an ultrasonic transmission signal having an initial amplitude (A0) through the measuring distance, a first ultrasonic reception device for receiving the transmitted ultrasonic reception signal after the signal has passed through the measuring distance, and a second ultrasonic reception device for receiving the ultrasonic receiving signal reflected on the boundary surface between the test material and the reference material after the signal has twice passed through the reference material or test material, the transmission device being configured for giving ultrasonic transmission signals having different frequencies (f) and the two reception devices being configured for receiving corresponding ultrasonic reception signals having different frequencies.

Abstract: A measuring device for measuring a hole in the ground having at least one measuring probe having at least one measurement signal transmitter to transmit a measurement signal, at least one measurement signal receiver to receive the measurement signal reflected on a wall area of the hole, and an evaluation unit for determining a wall distance between the measurement signal transmitter and the wall area of the hole, wherein a measuring distance based on an assignment rule can be assigned to the received, reflected measurement signal. A calibrating device having at least one calibration element. The measurement signal transmitter transmits a calibration signal, which can be reflected on the calibration element, wherein the measurement signal receiver receives the calibration signal reflected on the calibration element. The evaluation unit changes and calibrates the assignment rule based on the calibration signal reflected and received by the calibration element.

Abstract: A system for determining the position of a piston in a subsea accumulator, comprising: a sensor module comprising: a housing; an ultrasonic transducer facing the piston and configured to transmit an ultrasonic pulse through a fluid medium toward a surface of the piston; a pressure sensor configured to; and a temperature sensor; a control connector coupled to the sensor module capable of providing hardware and software functions to measure transit time of the ultrasonic signal from the ultrasonic transducer to the surface of the piston, comprising electronics for controlling the ultrasonic transducer, pressure sensor and temperature sensor; wherein the transit times of the ultrasonic signals across the fluid medium are measured and combined with a computed velocity of sound as a function of temperature/pressure to determine the distance between the ultrasonic transducer and the surface of the piston.

Abstract: A method for imaging formations below the bottom of a body of water includes imparting acoustic energy into the formations along a predetermined length swath at a selected geodetic position. Acoustic energy reflected from the formations is detected along a line parallel to the length of the swath. The selected geodetic position is moved a selected distance transverse to the length of the swath. The imparting acoustic energy, detecting acoustic energy and moving the geodetic position are repeated until a selected distance transverse to the length of the swath is traversed. The detected acoustic energy from all the selected geodetic positions is coherently stacked. The detected acoustic energy is beam steered to each of a plurality of depths and positions along the length of the swath to generate an image for each such depth and position.

Abstract: The invention relates to a method for determining the location of an impact on a surface of an object based on the analysis of an acoustic signal generated by the impact. This method further comprises a signal treatment step of weighting the acoustic signal to take into account spurious contributions in particular due to reflections at the border of the object.

Abstract: A system and method for compensating ultrasonic sensors mounted on a vehicle for speed of sound variations. The ultrasonic sensor is operatively coupled to a power train control module having a pressure sensor that continuously monitors atmospheric pressure and a controller configured for computing a compensated speed of sound using the monitored atmospheric pressure. The ultrasonic sensor sends an ultrasonic wave and determines the time lag in receiving the reflected ultrasonic wave from an object. Subsequently, the ultrasonic sensor generates a signal corresponding to the relative distance between the vehicle and the object using the compensated speed of sound and the time lag.

Abstract: Embodiments relate to monitoring the temperature of a transducer and controlling the temperature as a function of adjusting one or more characteristics of the transducer.

Abstract: Methods and apparatus for borehole seismic survey are disclosed comprising a first seismic source under water at a first location and a second seismic source at a second, deeper location. Seismic signals from the seismic sources are recorded with synchronized sensors located in a borehole and source signature data are obtained by combining the recorded seismic signals such that low and high frequency content of the combined source signature data is extended relative to the source signature of the first seismic source and the second seismic source.

Abstract: A distance measurement apparatus arranged to measure the distance to an object (106) comprising a first sonic transmitter (100) arranged at a first distance (h1) from that object and a second sonic transmitter (102) arranged at a second distance (h2) from that object (100), wherein the first and second distances are different, the first (100) and second (102) transmitters being controlled by processing circuitry (108) and the first and second transmitters being arranged such that sonic pulses emitted, in use, thereby are incident upon that object (106) and the apparatus further comprising at least one sonic receiver (100) arranged to receive a plurality of reflected sonic pulses and generate an output therefrom and the processing circuitry (108) being arranged to receive the output, determine the times since the first and second pulses were emitted and generate a distance to that object from the determined times.

Abstract: For an ultrasonic sensor at least one sensitivity parameter or sensitivity characteristics curve may be adjusted as a function of the air humidity and/or temperature in such a way that a predefined range or a range section may be reliably reached. Such a sensor makes it possible to reliably detect curbs, and to locate parking spaces, including curb detection under varying weather conditions.

Abstract: An ultrasonic sensor having a diaphragm includes a heating element for heating the diaphragm.

Abstract: The invention relates to an ultrasonic sensor with an adjustable detection range for use in gaseous media, preferably air. A threshold value generator generates threshold value curves that are fed to a comparator. The change in the detection range of the ultrasonic sensor, namely, the change in its switching point curve, is carried out by influencing the threshold value curves, whereby, in a selectable manner, the detection range can be adjusted either exclusively in the lateral extension of the sonic cone or else in the axial and lateral extensions of the sonic cone.

Abstract: An apparatus for automatically calibrating a transducer are disclosed in the present invention, the apparatus comprising: an oscillator, for generating a system frequency; a micro controller, being coupled to the oscillator, for receiving the system frequency; a counting unit, being installed inside the micro processor, for generating at least a clock signal according to the system frequency; a transformer, whose input terminal is being coupled to the counting unit, for receiving the clock signal and transferring the clock signal to be a plurality of exciting signals, the output terminal feedbacks and couples the exciting signals to the interrupting signal input terminal of the micro controller, wherein the a plurality of exciting signals comprising at least a primary oscillating signal and at least a secondary oscillating signal and the amount of the clock signal equals to that of the primary oscillating signal; and a transducer, whose input terminal is being coupled to the transformer, and the transducer is

Abstract: Apparatus is described for accurately determining the elevation, E, of a pulse-echo ultrasonic range sensor (2) relative to a datum level (14). The figure shows vertical elevations of the apparatus with plate deployed at level-1 (12) and level-2 (13) above a datum level (14), the levels being separated by a known distance, D. The elevation of the sensor is given by the relationship: R1=D|(dt1/(dt2?dt1))| where dt1 and dt2 are the intervals of time, determined by the sensor, taken by a pulse-echo to transit the distances R1 and R2 respectively. This apparatus may also be used to determine sonic velocity, Sv from: Sv=|2D/(dt2?dt1)|.

Abstract: The present invention is intended to provide an ultrasonic range finder to measure a distance quickly and precisely under different environments. The ultrasonic range finder comprises a casing, an ultrasonic transmitting/receiving unit, a signal processing circuit connected electrically with the ultrasonic transmitting/receiving unit in the casing, a group of operation buttons on the casing and a display unit. The ultrasonic range finder further comprises a calibration rod to provide a constant reference distance. The calibration rod includes a first end connected to the casing. The calibration rod further includes a second end extendable outwardly relative to the casing and a body between the first and the second ends. By measuring a propagation time of an ultrasonic signal within the constant reference distance an ultrasonic propagation speed can be determined quickly and precisely and thereby perform the distance measurement quickly and precisely without being affected by changes in the environment.

Abstract: A distance measuring device includes a transmitter for transmitting an acoustic signal at a distant object, an acoustic signal receiver for receiving a reflected acoustic signal reflected from the distant object, a temperature sensor detecting air temperature, a humidity sensor detecting air humidity, an amplifier amplifying the reflected acoustic signal, a comparator coupled to the amplifier comparing the amplified reflected acoustic signal with a reference and generating a comparator output when the level of the amplified reflected acoustic signal exceeds the reference, a gain controller increasing the gain from transmitting an acoustic signal until the comparator output is generated, a threshold generator providing the reference to the comparator and decreasing the reference at an exponential rate from transmitting the acoustic signal until the comparator output is generated, and a controller determining use of only the air temperature, velocity of the acoustic signal, and distance traveled from transmitti

Abstract: An apparatus for determining a position includes a source which transmits a signal having a source position and a transmission time coded therein. A sensor having a directional beam pattern is positioned at the location of interest. A signal processor steers the directional beam pattern of the sensor in order to determine the direction to the signal source. A sensor processor uses a clock to find a receipt time of the signal. The transmission time and source position is decoded from the signal. The position of interest is calculated from the receipt time, transmission time, direction, and source position. A method is also provided.

Abstract: An airborne sonar collision avoidance system is disclosed. The system compensates for changes in temperature in real time to provide more accurate sonar detection. In addition, the sensors are arranged in a communications network that allows for the sensors to be programmed at run time, thus providing the ability to relocate the sensors without having to pre-program the sensors before the sensors are installed onto a different location.

Abstract: An airborne sonar collision avoidance system is disclosed. The system compensates for changes in temperature in real time to provide more accurate sonar detection. In addition, the sensors are arranged in a communications network that allows for the sensors to be programmed at run time, thus providing the ability to relocate the sensors without having to pre-program the sensors before the sensors are installed onto a different location.

Abstract: An acoustic method for measuring of a distance between an emitter of acoustic energy and a target object provides for an accurate measurement by having the measurement's outcome invariant to the speed of sound variations along the acoustical path between the emitter and the target. A plurality of emitters and a plurality of receivers are used in the invention. One acoustic emitter and one receiver are located in a spatial region such that the sent and the reflected acoustical energy passes along substantially same vertical line between the emitter and the target. Another acoustic emitter sends the acoustical energy at an angled direction to the same area on the target's reflecting surface as the first emitter does. The corresponding echo travels to another receiver. During the measurement, two specific variables are being monitored such that possible variations of the speed of sound are irrelevant to the result of the distance measurement.

Abstract: An airborne sonar collision avoidance system is disclosed. The system compensates for changes in temperature in real time to provide more accurate sonar detection. In addition, the sensors are arranged in a communications network that allows for the sensors to be programmed at run time, thus providing the ability to relocate the sensors without having to pre-program the sensors before the sensors are installed onto a different location.

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: A sonic water level measuring method and system for mounting a wave-guide tube for measuring a water level in a reservoir, a river, etc. generating sonic pulses at the upper of the wave-guide tube, measuring transit times that it takes for the sonic pulses to transit from an original point to a water surface through air medium and transit back to the original point after being reflected on the water surface and multiplying the transit times by a sound velocity to compute a water level is configured to measure the sound velocity using the times that it takes for the sonic pulse to transit in two intervals in order to exactly measure the sound velocity that is changed according to the changing of an air temperature, pressure and component in the wave-guide tube and then measure the water level considering an arithmetical average value of the sound velocities measured as a sound velocity in the wave-guide tube.

Abstract: An apparatus for determining the velocity of sound waves which includes a liquid medium having a plurality of gas bubbles. In the liquid medium, a laser transmits a light pulse to interact with the bubbles excited by the sound wave. Backscattered light from the interaction of the light pulse is received. A processor is then responsive to the detector to provide detection of the acoustic wave through the fluid medium.

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: In a position detecting device which detects a piston rod based on the time elapsed from a point at which an ultrasonic wave is emitted from an ultrasonic wave sensor toward a lower end surface of the piston rod reciprocatingly moved linearly by supply and discharge of a working oil with respect to a hydraulic cylinder to a point at which the ultrasonic wave reflected by the lower end surface of the piston rod is received by the ultrasonic wave sensor, if the working oil's temperature is detected by a temperature sensor, then a microcomputer sets the strength of the ultrasonic wave emitted from the ultrasonic wave sensor in accordance with the temperature of the working oil so as to accurately detect the position of the piston.

Abstract: A system for determining the sound velocity profile in a medium, such as water, includes an acoustic signal transmitting system at a transmitting location and an acoustic signal receiving and processing system at a receiving location. In one example, the acoustic signal receiving and processing system is located in a submarine or other similar vessel, and the acoustic signal transmitting system is located in an expendable vehicle or probe that moves throughout the water surrounding the submarine or vessel. At one or more transmission times and transmitting locations, the acoustic signal transmitting system transmits an acoustic signal. The acoustic signal receiving and processing system receives each acoustic signal at an arrival time and determines the sound velocity in the water between the transmitting location and the receiving location using the arrival time, the predetermined transmission time, and the predetermined transmitting location.

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: 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: The invention is directed to an improved acoustic sensor system for detering the direction of underwater sound signals relative to a user is disclosed. The sensor system includes first and second sensing means for sensing incoming acoustic energy and for providing first and second acoustic energy signals in response thereto; separation means for separating the first and second sensing means a distance S=E(C.sub.W /C.sub.A) where E is substantially equal to the separation distance between the users ears, C.sub.W is the speed of sound in water, and C.sub.A is the speed of sound in air; detector means, operatively connected with the first and second sensing means, for providing first and second output signals in response to the first and second acoustic energy signals; and audio means, operatively connected with the detector means, for providing an audio output to the user in response to the first and second output signals.

Abstract: An ultrasonic probe utilized in an ultrasonic ranging system for determining fluid volume and/or fluid leakage in an underground storage tank, as well as monitoring fluid inventory, is provided which is characterized by (i) having its calibration reflectors positioned whereby each of the secondary echo packets formed by the calibration reflectors of the ultrasonic probe becomes imbedded into the trailing edge of a primary echo packet of another calibration reflector or to cause its secondary echo packet to be detected by the transducer after the transducer has detected a primary echo packet associated with the fluid surface, (ii) each of the calibration reflectors being positioned perpendicular to and offset from the longitudinal axis of the probe body, (iii) an ultrasonic sound wave dampening member fixedly positioned in the probe body between the transducer assembly and the tank bottom, the wave dampening member having a surface facing toward the transducer assembly wherein the surface is configured to damp

Abstract: An ultrasonic distance meter cancels out the effects of temperature and humidity variations by including a measuring unit and a reference unit. In each of the units, a repetitive series of pulses is generated, each having a repetition rate directly related to the respective distance between an electroacoustic transmitter and an electroacoustic receiver. The pulse trains are provided to respective counters, and the ratio of the counter outputs is utilized to determine the distance being measured.

Abstract: A calibration pipe having a predetermined length is connected to an end of a pipe to be measured. A sound emitter and a sound receiver are connected to a base end of the calibration pipe. The sound emitter emits a sound into the calibration pipe and the pipe to be measured, and the sound receiver receives a sound reflected from a discontinuous portion of the pipe. A calculator is provided for calculating a period of time from emitting of the sound to receiving of the reflected sound. The length of the pipe is calculated based on speed of the sound in the calibration pipe.

Abstract: An ultrasonic stand-off gauge for use in measuring the instantaneous stand-off distance between the drill stem and the borehole wall while drilling. A primary transducer mounted on the drill collar sends and receives ultrasonic pulses between the drill collar and the borehole wall. A second, reference transducer mounted on the pressure barrel within the drill collar measures the sound speed of the drilling fluid. The drilling fluid flows through a conduit within the drill collar, where the reference transducer transmits a pulse through the drilling fluid in the conduit. The pulse from the reference transducer is reflected off an internal reflector mounted on the internal surface of the drill collar. Since the distance between the reference transducer and the reflector is known and constant, the sound speed of the drilling fluid is determined accurately.

Abstract: An annular array scanner utilizes a synthetic focusing approach to improve imaging results. Image sharpening methods include corrections for the speed of sound of the image, phased array misregistration and separate view misalignment as well as inverse filtering for the scanning system point spread function.

Abstract: A detecting system and method of determining the position of a mobile point of interest in a m dimensional coordinate system having an ultrasonic transmitter mounted on the point of interest, and a plurality of stationary ultrasonic receivers, the number being at least m plus 2. The location of the receivers are determined optimally by using a linear matrix formulation. Alternatively, the location of the receivers can be determined during installation or self-calibration of the system. The system also includes receiver controlling means for processing the received signal to generate time of flight measurements which are used to eliminate the speed of sound as a variable and to compute the location of the point of interest. The controlling means also generates phase measurements when prompted by an outside source by comparing the transmitted signal with a 40kHz pulse sync to refine the accuracy of the location of the point of interest.

Abstract: In a position detection probe having a magnetostrictive wire stretched between a head and a reflective foot end termination, and a magnet displaceable along the probe and using the sonic pulse propagation time from the magnet to the foot as a position detection parameter, compensation for thermal expansion and thermal change of propagation velocity is made based on the property of the total propagation time along the wire length being a unique function of temperature and calibrating the probe at different temperatures to yield either equations or look up tables of true positions as functions of the total propagation time and the position detection parameter. By mapping wire characteristics at a plurality of magnet positions and temperatures to construct look up tables, wire nonlinearities as well as thermal effects can be compensated for.

Abstract: An acoustic pipe length measuring apparatus for measuring the length of a pipe-like member in accordance with the time between the emission of a pulse-like sound wave from a speaker at one end thereof and the collection of sound waves reflected at the other end thereof, by a microphone, and a sonic velocity, in which data of a sonic velocity at a reference temperature of a gas present in the pipe-like member is stored in memory, and a sonic velocity value at a temperature of gas detected in the pipe-like member is computed with the use of the data of a sonic velocity value which is read from the memory in accordance with a kind of gas in the pipe-like member, thereby it is possible to calculate the length of the pipe-like member from the sonic velocity value obtained through the computation and the above-mentioned time.

Abstract: A radar altimeter incorporates circuitry for automatically adjusting altitude readings for variations caused by altitude and temperature changes. Normal target tracking of the radar is intermittently interrupted and a calibration sequence is interjected. The current altitude and receiver AGC information at the time of each interruption is temporarily stored and a test is initiated in which a pseudo radar return at that altitude is introduced to the receiver. The receiver operates on the pseudo return as it would on an actual return. The transmit power is adjusted automatically for the correct signal level at the tracker. The resultant altitude measured for the pseudo return is compared to a known test altitude and any difference is stored away as a correction factor to be applied to the altitude reading which had been stored at the time that its operation had been interrupted to perform the calibration test.

Abstract: A system for monitoring level of material in a vessel that includes a transducer for transmitting an ultrasonic signal toward and receiving an echo signal from a surface of the material, and a power switch coupled to the transducer for energizing the transducer to transmit the ultrasonic signal. A microprocessor-based controller has an output coupled to the power switch for controlling operation thereof. The output of the microprocessor provides a pulsed periodic signal to the power switch at controllably variable frequency, duty cycle and/or total burst duration to operate the transducer at an ultrasonic frequency that corresponds to the periodic signal frequency, duty cycle and burst duration. The echo signals are compared to successive thresholds between the transmission bursts, and echo signal data is sampled and stored in the microprocessor over a measurement cycle that includes multiple transmission bursts.

Abstract: A master transceiver and a slave transceiver are employed for providing an accurate measurement of the distance between two locations in which these transceivers are situated. A pulse signal is generated by the master transceiver, which requires a time period of t1 to travel to the slave transceiver. After a time delay of t2 upon the receipt of the pulse signal by the slave transceiver it transmits a response signal back to the master transceiver. The response signal requires the same time period of t1 to be received by the master trasnceiver. The total time involved is compared with a reference time to distance circuit in the master transceiver to determine the distance between the two units and the distance is shown on a digital display.

Abstract: A depth finder utilizing a CPU to control the function of various components including a transducer, receiver, and a liquid crystal display, allowing a user to select between fresh and salt water operational modes as well as between English and metric display units. The CPU is controlled by a keypad and varies the rate at which stored transducer data is transferred from the receiver to the CPU such that the data is always representative of a fixed depth increment in any operational mode.

Abstract: A technique for the non-intrusive position determination of one or more natural or artificial acoustic transmitters (S1, S2, S3) in marine or terrestrial environments by processing data from five or more receivers (R1, R2, R3, R4, R5) distributed in the area. The data processing includes cross correlation (24) of receiver data to determine differences in acoustic data travel times (MTTD) and tomographic reconstruction (16) to determine transmitter position as well as receiver position (42), wind or current (40) and sound speed or temperature fields (44) and errors (41) associated with all of the above. Accuracy can be greatly enhanced by use of calibration transmissions at receiver or other known or unknown position locations. Position and wind, sound speed and error fields may conveniently be displayed by computer generated maps (18, 20, 22, 43).

Abstract: In a marine seismic survey, a method for measuring the acoustic properties of the water mass at each seismic station along a line of survey by recovering acoustic reflections from discrete discontinuities within the water above the water-bottom reflection. A profile of the velocity distribution within the water column is calculated from a conventional velocity analysis.

Abstract: An ultrasonic distance sensor generates ultrasonic waves and transmit same toward a target surface, the distance to which is to be measured, through a predetermined path. The sensor is also provided with a reference surface which reflects ultrasonic waves, which reference surface is disposed within the aforementioned predetermined path of the ultrasonic waves. A receiver associated with delayed pulse generators receives the ultrasonic waves reflected by the reference surface or by the target surface, selectively. Arithmetic operations based on the elapsed time between transmission of the ultrasonic waves and reception of the ultrasonic waves from the reference surface derive the transmission velocity of the ultrasonic wave based on the known distance to the reference surface. On the basis of the derived transmission velocity and the elapsed time measured with respect to the ultrasonic waves reflected by the target surface, the distance to the target surface is derived.

Abstract: A temperature compensation system that adjusts the temperature of an acoustic lens fluid in a prescribed manner to maintain the index of refraction of the fluid constant relative to the surrounding water thereby maintaining the focal length of the lens constant over its operating temperature range. The system comprises two temperature sensors, a programmed lens fluid temperature prescriber and an error amplifier all cooperating to direct a servomechanism system to adjust a temperature control system to either heat or cool the lens fluid to the prescribed temperature so that its index or refraction and focal length are held constant.

Abstract: A system for measuring the position of a moving object including transceiver means for sending signals to and receiving signals reflected from both a moving object and a reference object maintaining a known, fixed distance from the moving object, wherein by processing the signals sent and received, the position of the moving object can be determined while the effects of temperature on the speed of sound, frequency changes, false echoes and erroneous signals are minimized or eliminated.

Abstract: An ultrasound echo profile sensor for use as a tactile sensor, having an ultrasound measuring head containing a transmitter and a receiver and also having an entrained reference reflector by means of which the current speed of sound of the ambient air can be identified. The respective distance of the tactile sensor from a sensor subject can be correctly measured independently of the variable speed of sound of the ambient air because a reference echo caused by the reference reflector can be discriminated from situation echoes on the basis of its known, proximate position. The reference reflector, whose distance from the ultrasound receiver is constant in the reference case, is arranged such that the distance between the ultrasound receiver and the reference reflector changes in a characteristic way given tactile contact between a sensor head and the sensor subject, particularly a workpiece.