Abstract: Apparatus for indicating the oil level in a central heating oil tank comprises a battery powered monitoring unit (1) for mounting on the oil tank which determines the oil level by an ultrasonic signal transmitter/receiver (18). A first microprocessor (14) in the monitoring unit (1) determines the oil level from the ultrasonic transmitter/receiver (18) and operates a primary transmitter (12) for transmitting a radio signal which includes data indicative of the oil level. A remotely mounted mains electricity powered receiving unit (3) comprises a primary radio receiver (15) for receiving the transmitted signal, and a second microprocessor (16) in the receiving unit (3) controls the operation of a visual display unit (10) for graphically displaying the oil level. The monitoring unit (1) and the receiving unit (3) are operable in a teaching mode initially on power-up of the receiving unit (3) during which the monitoring unit (1) teaches the receiving unit (3) its address.

Abstract: A method and apparatus for damping an ultrasonic transducer suitable for time of flight ranging and level measurement systems. The ultrasonic transducer comprises a damping component which absorbs vibrations in the transducer to reduce the ringing effect. The damping component is subjected to plasma etching to produce a surface which readily bonds to component(s) of the transducer. According to one aspect, the damping component is formed from an inert elastomer, such as silicone rubber, and the transducer component is made of stainless steel.

Abstract: A non-invasive method for measuring the level of filling material in a vessel and for detecting the presence of the filling material in the vessel at a predetermined set point level is based on monitoring the oscillation of the vessel's outside wall that follows an impact load applied to the external surface of the vessel's wall. The method may employ short range level measurement and long range level measurement procedures. The short-range level measurement utilizes the macro-dynamic properties of the oscillating space in the vicinity of the center of the impact. The long-range level measurement utilizes the properties of the transverse elastic waves propagating along the vessel's wall after the impact. The value of the measured level may be determined by a joint evaluation of the output of the short range level measurement procedure and the output of the long range level measurement procedure.

Abstract: An arrangement for fill level measurement is provided, with which accurate fill level measurement on a continuing basis is possible, including a container (3) containing a fill substance (1) whose fill level is to be measured, a fill level measuring device (5) arranged at the container (3) and operating according to the travel time principle, an apparatus (11, 13) for registering a filling and/or emptying of the container (3), an auxiliary unit (19), which by means of the filling and/or emptying registered by the apparatus (11, 13), determines an instantaneous change in fill level (VL) or an instantaneous change in material flow rate, and makes such available to the fill level measuring device (5) for determining the fill level (L) to be measured.

Abstract: A device for establishing and/or monitoring a predetermined fill level in a container is provided, which also operates stably in liquids with surface waves, which includes: a mechanical oscillatory structure placed at the height of the predetermined fill level, an electromechanical transducer, which in operation excites the oscillatory structure to resonance oscillations, and a receiver- and evaluation-unit, which serves for determining from the resonance oscillation whether the predetermined fill level has been reached, or not, in which a shape of the oscillatory structure is so constructed that the resonance frequency changes only slowly with immersion depth in the case of immersion in the region of the predetermined fill level.

Abstract: The invention provides a device for controlling the composition and/or volume of a fluid within a reservoir. The device includes a reservoir adapted to contain at least one fluid, a means for monitoring a characteristic of the fluid contained in the reservoir, and a means for introducing additional fluid into the reservoir according to the fluid characteristic monitored by the monitoring means. The device also includes an acoustic generator for generating acoustic radiation. A dispensing means may be provided as well. Other devices and methods that use acoustic radiation to control the composition and/or volume of a fluid within a reservoir are included.

Abstract: A microwave-based level measurement system having a planar microwave antenna configuration. According to another aspect, the microwave-based level measurement devices are field interchangeable with ultrasonic based level measurement devices.

Abstract: A pulse offset calibration method for a pulse-echo level measurement system. The pulse-echo level measurement system includes a transducer for transmitting calibration acoustic pulses and receiving echo pulses. A receiver converts the echo pulses into corresponding pulse profile signals having a leading edge. A static delay interval is defined on the leading edge corresponding to the time interval between the reception of the echo pulse and the response by the receiver. A dynamic delay interval is defined on the leading edge corresponding to the time response characteristics of the transducer and the receiver. The static delay interval and the dynamic delay interval are summed to determine the offset time interval for the echo pulse. The offset time interval is subtracted from the measurements to provide the true duration for the time of flight.

Abstract: A method and system for echo processing a receive signal using autocorrelation. A receive signal is sampled, digitized and high-pass filtered. A correlation signal is created by adding the filtered signal to a copy of the filtered signal shifted by a time unit. A set of correlation signals is created by repeating the process for a range of time units corresponding to a set of sequential sample points. Each correlation signal has a correlation indicator evidencing the strength of the correlation. The correlation signal having the highest correlation strength is identified, and the time shift used to create it is identified as the time of flight of the echo pulse. The echo distance is then calculated based upon the time of flight and the speed of propagation of the echo in the environment. The correlation indicator may the maximum peak value of the correlation signal.

Abstract: A method for processing echoes in a time-of-flight ranging system or level measurement system. The method comprises an initial noise floor level and identifying potential echoes in an echo signal above the initial noise floor level and a noise signal below the initial noise floor level. One or more portions of the initial noise floor level are modified and an adjusted noise floor level is generated by applying a cubic spline algorithm to the modified portions and the initial noise floor level. The adjusted noise floor level is then used to identify valid echoes in the echo signal and generate an echo signal profile.

Abstract: A method and system for echo processing a receive signal using autocorrelation. A receive signal is sampled, digitized and high-pass filtered. A correlation signal is created by adding the filtered signal to a copy of the filtered signal shifted by a time unit. A set of correlation signals is created by repeating the process for a range of time units corresponding to a set of sequential sample points. Each correlation signal has a correlation indicator evidencing the strength of the correlation. The correlation signal having the highest correlation strength is identified, and the time shift used to create it is identified as the time of flight of the echo pulse. The echo distance is then calculated based upon the time of flight and the speed of propagation of the echo in the environment. The correlation indicator may the maximum peak value of the correlation signal.

Abstract: A calibration module and methods for a time-of-flight ranging system. The calibration module may be built into the circuitry of the time-of-flight ranging system and allows various operating parameters to be measured and evaluated. The calibration modes include amplitude calibration, frequency calibration, and time delay calibration. The calibration mode also includes an electronic noise measurement mode. The calibration modes may be initiated on power-up or reset, or in response to user input or time-based trigger.

Abstract: This invention relates to a level-measuring device in which a signal generating device, a sampling device and a transmitting and/or receiving device are optimally connected to one another for various applications and signal shapes. The signal generating device generates both a radio-frequency transmit signal and a sampling control signal for sampling the radio-frequency signal. The sampling device, the signal generating device and the transmitting and/or receiving device being connected by a coupling device which comprises one of: a transformer; at least one line node; a &lgr;/4 coupler and a circulator.

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: A device for measuring a fill level of liquid in a container includes a measuring tube arranged inside the container and an ultrasonic sensor arranged outside the container such that a portion of the wall of the container is arranged between the measuring tube and the ultrasonic sensor. The ultrasonic sensor therefore has no contact with the liquid located in the container.

Abstract: A power saving system and method for the analog-to-digital converter stage in a time of flight ranging system. A receiving echo signal having an envelope is converted into a digital form suitable for further processing by sampling the received echo signal envelope at precise intervals to obtain amplitude measurement points. An interpolation function is applied between each pair of adjacent amplitude measurement points. The application of the interpolation function provides a closer approximation of the shape of the received echo signal envelope without the need to use higher sampling rates which means slower analog-to-digital converters may be utilized resulting in power and cost savings.

Abstract: A method of detecting actual or incipient submersion of an electroacoustic transducer (2) facing downwardly toward a surface of fluent material to be sensed in a pulse-echo acoustic ranging system, the transducer having a skirt (6) surrounding a downwardly facing radiating surface (4) to maintain an air space (10) beneath the radiating surface even under submergence conditions, and the transducer being electrically energized to emit pulses of acoustic energy from the radiating surface, the system processing an electrical output received from the transducer following a pulse by repeatedly sampling it to obtain a response profile. Samples from an initial portion of the response of the transducer during a ring-down period following the transmit pulse are summed (FIG.

Abstract: A method of tracking an object comprising the steps of acquiring the position of at least one object; selecting the at least one object as a target; determining a sampling window which envelopes the target; obtaining an echo; repeating the foregoing step of obtaining an echo a predetermined number of times; determining valid echoes from the target; calculating the current position of the target from the received echoes; and repeating the steps of obtaining, repeating, determining, and calculating as desired. The step of obtaining an echo comprises the steps of transmitting a pulse at a desired frequency from a transducer; scanning for echoes within the sampling window by a receiver; and receiving at least one echo of the pulse at the receiver which are within the sampling window, the at least one echo having a frequency that matches the outgoing pulse frequency.

Abstract: A method of tracking an object comprising the steps of acquiring the position of at least one object; selecting the at least one object as a target; determining a sampling window which envelopes the target; obtaining an echo; repeating the foregoing step of obtaining an echo a predetermined number of times; determining valid echoes from the target; calculating the current position of the target from the received echoes; and repeating the steps of obtaining, repeating, determining, and calculating as desired. The step of obtaining an echo comprises the steps of transmitting a pulse at a desired frequency from a transducer; scanning for echoes within the sampling window by a receiver; and receiving at least one echo of the pulse at the receiver which are within the sampling window, the at least one echo having a frequency that matches the outgoing pulse frequency.

Abstract: For use with a high gain receiver circuit which receives echo pulses of frequencies within a predetermined bandwidth and at times within interpulse periods of a predetermined pulse repetition rate and amplifies the echo pulses for measurement purposes, the receiver circuit susceptible to electrical noise within the frequency bandwidth of the received echo pulses to create false echo pulses, a method of eliminating substantially the false echo pulses without affecting substantially the amplified echo pulses by accepting only echo pulses which occur synchronously among interpulse periods. The pulse repetition rate may be varied to eliminate false echo pulses that are synchronous to the interpulse periods.

Abstract: A level sensing apparatus for attachment to a vessel to measure levels of contents in a tank of the vessel. The level sensing apparatus includes a housing, a transmitter disposed within and operatively connected to said housing, and an antenna operatively connected to the transmitter for directing electrical and/or mechanical waves in a direction away from the transmitter. The antenna is further adapted to receive electrical and/or mechanical waves. The level sensing apparatus further includes a mounting system affixing the level sensing apparatus to a vessel. The mounting system is adapted such that the mounting system can be placed in a first position while the transmitter is affixed to the vessel, wherein levels of contents in a tank can be measured with electrical and/or mechanical waves, or in a second position while the transmitter is affixed to the vessel, wherein levels of contents in a tank can be measured manually.

Abstract: The present invention pertains to a method for range measurement by means of a signal transmitted in the direction of an object to be measured, wherein an echo signal, on which is superimposed a first reference pulse, is received by a receive device, wherein the echo signal is compared with a second reference signal that features a second reference pulse for determining a signal travel time, and wherein a first comparison value of the echo signal and a second comparison value of the second reference signal are compared with each other for determining an amplitude offset between the echo signal and the second reference signal, and these values, in regards to time, are before the first and second reference pulses in a region of the echo signal curve and of the second reference signal curve, respectively, and in these regions, these curves feature a slope that is at least approximately zero.

Abstract: An underwater detection apparatus comprises a transducer, a transmitter capable of generating transmitting signals of a plurality of respective frequencies and for generating a transmitting signal, a broadband trap circuit for transferring the transmitting signal fed from the transmitter to the transducer and for passing an echo signal fed from the transducer, a preamplifier for amplifying the echo signal fed from the broadband trap circuit, a mixer for converting an output of the preamplifier into a signal of a specific frequency, a filter for selectively passing the signal of only the specific frequency-band output from the mixer, a main amplifier for amplifying an output of the filter, an A/D converter for converting an output of the main amplifier into a digital form, and a display circuit for displaying the digitized output of the A/D converter on a monitor, wherein the preamplifier is of a low-gain type.

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 them through air medium and transit back to an original point after being reflected on the water surface, and multiplying the transit times by a sound velocity to compute a water level comprises steps of measuring 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 measuring the water level considering an arithmetical average value of the sound velocities measured as a sound velocity in the wave-guide tube.

Abstract: A method and apparatus for determining the surface level of a given body using acoustic ranging that incorporates processes natural to human beings to improve identification of the echo from the water surface when spurious echoes might otherwise overshadow it. An acoustic beam is transmitted toward the surface where it is reflected. The beam also reflects off various interferences creating spurious reflections or echoes. The echoes from the surface as well as the spurious echoes are then received. Each echo is then evaluated according to several criteria, in order to determine which echo is associated with the surface.

Abstract: A level sensing apparatus for attachment to a sounding tube in order to measure levels of contents in a tank. This level sensing apparatus includes a housing for enclosing the various components of the level sensing apparatus. The level sensing apparatus of the present invention also includes a sounding tube adapter operatively connected to the housing and is further adapted for attachment to a sounding tube. Additionally, the sounding tube adapter includes an orifice disposed through its sidewall. The sounding tube adapter also includes a cover which can seal off the orifice, or may be opened to allow manual liquid level measurement.

Abstract: An ultrasonic distance measuring system for monitoring railroad car loads. The system includes an ultrasonic transducer, a pulse generation and detection circuit and a measurement circuit. The transducer produces a transmitted ultrasonic pulse beam to be directed at a load in a railroad car and receives a return pulse beam from the load. The pulse generation and detection circuit is coupled to the transducer and causes the transducer to produce the transmitted pulse beam. A return pulse beam is detected by the pulse generation and detection circuit. The measurement circuit is coupled to the pulse generation and detection circuit and generates a measurement signal representative of the load as a function of the time delay between the transmitted and return pulse beams.

Abstract: A method of measuring the position of a target feature in a pulse-echo ranging system including transmitting at least one pulse of high frequency energy from a transducer towards the target feature, receiving energy reflected back from the direction of the target feature to the transducer to provide at least one return signal, repeatedly sampling the amplitude of the return signal(s) at intervals to form a digital database relating signal amplitude to elapsed time, and searching the database for at least one target zone in which a greater than background rate of fall of the return signal amplitude is sustained.

Abstract: A level sensing apparatus for attachment to a sounding tube in order to measure levels of contents in a tank and for determining the purity of contents in a tank. This level sensing apparatus includes a housing for enclosing the various components of the level sensing apparatus. The level sensing apparatus of the present invention also includes a sounding tube adapter operatively connected to the housing and is further adapted for attachment to a sounding tube. Additionally, the level sensing apparatus includes a lock operatively connected to the sounding tube adapter and capable of receiving the housing. Finally, the level sensing apparatus includes a swivel connector operatively connected to the housing, whereby the housing is capable of moving cooperatively with the swivel connector.

Abstract: An assembly for monitoring a predetermined level of a material in a container comprises two ultrasonic transducers mounted on the container in line with the level to be monitored, such that an interspace exists between the ultrasonic transducers into which the material enters on attaining the level to be monitored. The one ultrasonic transducer is an emitter transducer which at predetermined points in time for emitting ultrasonic pulses is energized by a frequency which is so low that the ultrasonic pulses are transmitted through the interspace to the detector transducer even when the interspace is filled with air. The other ultrasonic transducer is a detector transducer which converts detected ultrasonic pulses into electrical detection signals.

Abstract: This invention relates to an apparatus for the determination of the fill state of solid or liquid material in a container with a signal-generating/transmitting unit, a receiving unit, a time-delay circuit which transforms the high-frequency signals into low-frequency signals, and an evaluating unit.

Abstract: A sludge blanket level is determined in a waste water treatment clarifier using sonic pulse reflections. Additionally, using similar techniques, the clarity of the waste water is determined. A sonic pulse is directed into the waste water. Echos are generated as the pulse encounters the impedance mismatches indicative of changes in the density of the water. The echos are compensated for attenuation as a function of travel time through the water, energy lost due to prior peak reflections, and are processed to remove random signals using correlation techniques. A sludge blanket is selected from the compensated echo signal as a function of the size and location of echo peaks. Additionally, the clarity is determined as a function of the area under the echo signal between two points corresponding to predefined levels in the clarifier tank.

Abstract: A method for processing an echo amplitude profile generated by an echo ranging system with reference to a temporal axis to identify return echoes comprised by the profile by identifying amplitude peaks in the profile above with respect to an amplitude axis, a threshold curve on the same temporal axis, wherein the threshold curve is generated by identifying rising edges of echoes in the profile, and generating curve segments extending on the temporal axis from points at or above said leading edges to intersections with descending edges of echoes in the profile, whereby to trace echo base lines delimiting access of the echoes. The invention also extends to a method for processing an echo amplitude profile.

Abstract: A sludge blanket level is determined in a waste water treatment clarifier using sonic pulse reflections. Additionally, using similar techniques, the clarity of the waste water is determined. A sonic pulse is directed into the waste water. Echos are generated as the pulse encounters the impedance mismatches indicative of changes in the density of the water. The echos are compensated for attenuation as a function of travel time through the water, energy lost due to prior peak reflections, and are processed to remove random signals using correlation techniques. A sludge blanket is selected from the compensated echo signal as a function of the size and location of echo peaks. Additionally, the clarity is determined as a flnction of the area under the echo signal between two points corresponding to predefined levels in the clarifier tank.

Abstract: Noninvasive method for determining the liquid level and density inside of a container having arbitrary dimension and shape. By generating a flexural acoustic wave in the container shell and measuring the phase difference of the detected flexural wave from that of the originally generated wave a small distance from the generated wave, while moving the generation and detection means through the liquid/vapor interface, this interface can be detected. Both the wave generation and wave detection may be achieved by transducers on the surface of the container. A change in the phase difference over the outer surface of the vessel signifies that a liquid/vapor interface has been crossed, while the magnitude of the phase difference can be related to fluid density immediately opposite the measurement position on the surface of the vessel.

Abstract: A continuous measurement of the level of contents in a container is effected by a level measuring device functionong in accordance with the transit time principle by means of waves transmitted from a position located above the highest possible contents level onto the surface of the material in the container. A measuring circuit determines the contents level from the transit time of the useful echo reflected from the material surface. In addition, one or more limit sensors are located at the container, each of which furnishes a signal indicating whether the contents level is above or below a level to be monitored by the limit sensor and which is situated between the minimum and maximum contents levels of the container. The measuring circuit receives the output signals of all limit sensors and uses these output signals to check and eventually to correct the contents level measured value determined by the level measuring device.

Abstract: Apparatus for discriminating true echoes from false echoes in an ultrasonic liquid gauging system, comprising: means for producing electrical representations of an echo sequence received after an ultrasonic transmission, wherein the echo sequence contains one or more returned echoes that may be a true or false echo; and means for determining returned echo energy, wherein echo energy is a factor used to distinguish a true echo from a false echo.

Abstract: A vibrating probe for detecting a threshold level within a vessel of fluent material, particularly a liquid, includes: an ultrasonic acoustic transducer assembly comprising a transducer element having a natural resonant frequency, and loading elements effective to shift that frequency to an effective resonant frequency of the assembly, the assembly being supported within the vessel and including a coupling member to couple the transducer acoustically to liquid reaching the threshold level, a transmitter generating pulses applied to the transducer element for repeatedly exciting the transducer element to cause the transducer assembly to resonate at its effective resonant frequency, a circuit for measuring the effective resonant frequency of the transducer over a ringdown period following cessation of each pulse, and a circuit for comparing the effective resonant frequency measured during the ringdown period following each pulse with a predetermined threshold level.

Abstract: The invention concerns pulse echo distance measurement and in particular a method and apparatus for calculating such a distance by sensing multiple reflections of a given pulse signal. By sensing multiple reflections, and not just the primary echo, internal time delays which would otherwise cause systematic errors may be simply eliminated and the multiple readings obtained may be utilized to provide system self-diagnostic checks, eliminate spurious information and provide an accurate measure of distance. A particular advantage of the method is that very small distances between sensor and target may be measured.

Abstract: Method for processing echoes received in an ultrasonic liquid gauging apparatus includes the steps of transmitting at time t.sub.1 ultrasonic energy from an ultrasonic transducer toward a fixed target and a liquid surface; producing a transmission pulse corresponding to the time t.sub.1 ; receiving during a predetermined cycle interval a number (i) of ultrasonic echoes after t.sub.1 and converting each echo into a corresponding echo pulse having an associated time of arrival t.sub.i+1 ; and calculating the liquid level based on an averaged time of arrival of the second echo relative to t.sub.1 when it is known that the liquid surface is low.

Abstract: For monitoring a predetermined level of a liquid in a container an ultrasonic transducer is fitted on the outer surface of the container wall at a measurement point situated at the height of the level to be monitored. The ultrasonic transducer contains a piezoelectric element which generates, when excited by an alternating voltage pulse having a given transmission frequency, an ultrasonic transmission pulse which is transferred via a diaphragm to the container wall and which converts ultrasonic vibrations transferred from the container wall to the ultrasonic transducer into electrical reception signals. So that the piezoelectric element for given dimensions can be operated in a large frequency range, and so that a good adaptation to the diaphragm is achieved, the piezoelectric element consists of a porous piezoelectric ceramic having a type 3--3 connectivity.

Abstract: A sonic transducer shroud is shaped to present an inclined surface to rising bubbles and other matter during water treatment. Attached to the face of the sonic transducer, the shroud prevents the bubbles and other matter from being trapped on the transducer measurement surface and subsequently interfering with echo reception. The shroud has acoustic properties that are matched to the water such that the shroud is substantially acoustically transparent.

Abstract: A gas gun is provided for generation of an acoustic pulse and subsequent detection of return reflections from the annulus of a well. The system includes a gas gun and a hand-held gas source. The hand-held gas source comprises: a two-part housing forming a chamber for receipt of a small CO.sub.2 gas cartridge commonly used for CO.sub.2 target pistols; means for piercing the gas cartridge and pressurizing the chamber; a coupling for releasable connection to a delivery assembly; a passageway leading from the chamber to the coupling; and a first valve in the passageway for controlling release of gas from the chamber.

Abstract: In distance measurement on the principle of pulse transit time in each measurement cycle in a transmitting phase a transmission pulse having a given transmission frequency is emitted and in a subsequent receiving phase the envelope of the received signals is formed to determine the transit time of the useful echo pulse. For suppressing the fixed target echoes a broken line of several segments surrounding the envelope of the fixed target echo is formed for each fixed target echo. For each segment, information as to the amplitude of the end point of the segment, as to the changing direction and slope of the segment, as well as for the first segment information as to the point in time of the start of the first segment in the measurement cycle are stored.

Abstract: A time-domain reflectometer is disclosed for reliably measuring the level of a liquid in a tank. The reflectometer emits an acoustic signal into a waveguide that projects downwardly into the tank and receives a return acoustic signal reflected from the surface of the liquid. The time delay between the transmitted acoustic signal and the reflected acoustic signal is a measure of the level of the liquid, and the reflectometer converts this level measurement into a electrical current that is linearly proportioned between predetermined minimum and maximum values. In addition, the reflectometer incorporates a liquid- and vapor-impervious membrane disposed in the path of the transmitted and reflected acoustic signals, adjacent to the transmitter and receiver, to prevent the escape of liquid and vapor from the tank and to isolate the electronics, including the transmitter and receiver, from such liquid and vapor.

Abstract: One or more high-frequency ultrasonic transducers are used to measure the liquid level of tanks containing any type of fluid, but fuel in particular. The invention relates specifically to tanks that are subject to movement and vibration which generally makes the use of ultrasonic echoes unreliable for obtaining accurate level measurements. A special algorithm is used to obtain the temporal center of the distribution of echo arrival times over a preset time interval. From this temporal center of an echo distribution, the liquid level is readily obtained through the acoustic velocity, time and distance relationship. An annular piezoelectric plate, independently driven at low ultrasonic frequencies (kHz range), mounted on the tank bottom surrounds the high frequency ultrasonic transducer.

Abstract: A method and device for ultrasonic ranging. As in prior art devices, ultrasound pulses are transmitted by the device towards a target, and echo pulses from the target are received. The timing of the maximum of the amplitude envelope of the echo pulses is picked and used as a measure of the return time of these pulses. This maximum envelope time is relatively independent of the speed of sound between the device and the target. Preferably, the duration of the echo pulses is less than the response time of the receiving circuit, to enable an accurate pick of the amplitude envelope maximum.

Abstract: For monitoring a predetermined level of a liquid in a container an ultrasonic sensor is fitted on the outer surface of the container wall at a measurement point situated at the height of the level to be monitored, said sensor containing an ultrasonic transducer having a diaphragm in contact with the container wall. The components of the ultrasonic sensor including those of the ultrasonic transducer are grouped together in a sensor block which is releasably connected to an adapter secured to the container wall, this adapter being configured so that it can be secured in any way required to containers of differing shape and/or material.

Abstract: A high reliability instrument system includes means for applying a test condition to the instrument and for determining whether the instrument properly responds to the test condition, and means for inhibiting the generation of an instrument output in response to such testing. This provides verification that most of the instrument system components, but not the system output, are properly functioning. The system further includes means for overriding the output-inhibiting function when it is desired to test the entire instrument system including the system output. The instrument system may include a gap-type ultrasonic instrument, with the test condition comprising a pulse applied to one crystal, the effects of which are detected at the other crystal to determine sensor integrity. The system is preferably configured as a two-wire on-off instrument system, in which application of the test condition at a transmitter is controlled by signals applied to the two-wire signal loop at a remote receiver.

Abstract: A measuring apparatus and method for calculating height and weight of human subjects in one step. A scale having a weight sensor is provided to sense the weight of a subject standing thereon. A sonar head is positioned stationary a predetermined distance above the scale sufficient to permit a subject to stand upright on the scale and below the sonar head. The sonar head has a sound wave emitter and a plurality of sound wave receptors. A Digital Signal Processing circuit(DSP) is connected to the sonar head and is activated when the operator initiates a measurement. The data processing circuit is controlled by a software to calculate the weight and height of the subject. The apparatus and method also provides additional data on the subject, such as the body surface area, BA, body mass index BMI, percentiles height and weight. The (DSP) circuit produces a short burst of sound waves that travel downwards, hit the target (patient's head) and return towards the sonar head.