Abstract: A high liquid level sensor comprising a tubular probe, with a peripheral wall (6), and arranged to be suspended in a liquid container. An ultrasonic signal is transmitted around the wall (6) from a transmitting transducer (12) potted in a block (11), which is bonded to the inner surface of the wall, to a receiving transducer also potted in the block. A detector circuit connected to the receiving transducer via a lead (10) discriminates between the signal level when the probe is immersed in gas and the lower signal level when the probe is immersed in liquid, and provides a corresponding switched output.

Abstract: An apparatus for detecting the amount of toner in the supply hopper of an electrophotographic copying machine includes a transmitting element in the hopper for generating an ultrasonic acoustic wave and a receiving element in the hopper in operative relation to the transmitting element for receiving the ultrasonic acoustic wave reflected from toner in the hopper, the magnitude of the reflected wave being representative of the level of toner contained in the hopper.

Abstract: An apparatus for detecting a residual quantity of toner remaining in the supply hopper of a copying machine includes a piezoelectric vibrating element disposed in a wall of the hopper and having a surface normally positioned in contact with toner in the hopper, and an electronic circuit for causing vibration of the element at a predetermined frequency and for detecting changes in operating characteristics of the element as representative of a decrease in the amount of toner in the hopper to operate a warning device.

Abstract: A position determining apparatus comprising a taut electrically-conductive member; a pulse generator to feed a pulse of electric current along the member; a magnet located at a variable first point along the member, for example on a float on the surface of a liquid the level of which is to be determined, to apply a magnetic field to the member at that point; and a transducer positioned at a second point along the member to sense the arrival at the second point of a mechanical impulse induced in the member by interaction between the current pulse and the magnetic field as the current pulse passes the magnet. A time measuring circuit responsive to the time interval between the feeding of the current pulse and the arrival of the mechanical impulse at the second point is used to determine the position of the first point.

Abstract: An apparatus for sensing the level of the glass batch in a glass-melting furnace. The apparatus comprises means for transmitting an ultrasonic signal toward the surface of the batch in the furnace, means for receiving the ultrasonic signal after it has been reflected by the surface of the batch, and means for distrubing a thermal inversion layer in the path of the ultrasonic signal in the gaseous medium between the means for transmitting and the surface of the batch. The means for transmitting, means for receiving and means for disturbing are positioned above the glass batch.

Abstract: An ultrasonic system for sensing a liquid-fluid interface comprises a support structure (10) to which a transmitting crystal (21) and a receiving crystal (22) are bonded in such a way that the crystals (21 and 22) are positioned opposite each other across a gap (30). Each of the crystals (21 and 22) has a relatively high resonant frequency and a relatively low resonant frequency. An amplifier means (40) and a bandpass filter means (50) are connected to the crystals (21 and 22) to form a feedback loop. In normal operation, the transmitting crystal (21) is excited to resonate at its high resonant frequency in order to cause transmission of an ultrasonic signal across the gap (30) without causing appreciable ultrasonic transmission through the support structure (10) to the receiving crystal (22).

Abstract: Methods and systems employing acoustic techniques are disclosed for determining the level of fluid in a container. Flexural mode acoustic waves are set up in the walls of the container. The change in travel time of flexural mode acoustic waves are measured and calibrated in terms of the level of fluid in the container. Systems for continuously monitoring fluid level or indicating when fluid level reaches a predetermined horizontal level are disclosed.

Abstract: A float is disclosed for use in tank gauging systems of the type having a vertically supported guide. The float includes a donut-shaped body member adapted to be positioned about the guide to ride freely with the liquid surface. A discharged tube is positioned concentrically with the body member by a number of support members. The discharge tube is positioned below the liquid surface and acts as a discharge electrode to maintain the path of least resistance for an electrostatic discharge of the float below the liquid surface.

Abstract: A device for measuring the density of a liquid relies on the generation of resonant modes in a torsional vibration set up in a paddle which is immersed in the liquid. The frequency at which a resonance mode, usually a fundamental, is produced is a function of the density of the liquid. A feedback circuit is described which varies the frequency of an oscillator producing the vibrations so as to enable the frequency at which the resonance mode exists to be automatically found. Transducers for generating and detecting the torsional vibration are located at one end of a rod above the surface of the liquid, and the paddle is mounted on the other end of the rod.

Abstract: An apparatus is disclosed for the continuous measurement of the level of liquid in a container, wherein a flexible cable extends into close proximity or engagement with the floor of the container and comprises the oscillation determining element of an oscillator. The cable has a length greater than the distance between its mount to the container and the bottom of the container, and is doubled over at least part of its length to form an arc or loop at the container floor. A support engages the cable adjacent the container floor and holds the cable so that the arc or loop maintains its position relative to the container floor even though the container floor may sag or bulge, or the spacing between the floor and top of different containers varies because of manufacturing tolerances and the like.

Abstract: A liquid storage tank contents gauge comprises means providing an electrical signal corresponding to the vertical height of the liquid in a tank in the form of an ultrasonic transducer positioned at the base of the tank and emitting a pulse of acoustic energy vertically upwards and which detects the pulse when reflected from the liquid/air interface within the tank and including timing means provided to time the interval between the emission of the pulse and the detection of the reflected pulse, electronic means for deriving the volume of liquid corresponding to the vertical height, and an output means for providing a visual output of this volume.

Abstract: The level of mud in the mud return line of a rotary drilling rig is determined by cutting a hole in the top of the line and securing over the hole the saddle shaped base flange of a heat insulated sound tube supporting the ultra sonic transducer of an air coupled sonar distance measuring apparatus. The apparatus continuously digitally displays the average mud level. Upon a first manual command the apparatus makes a printed record of the level, time, and date.The apparatus give an alarm signal whenever the time averaged level departs a predetermined amount from a previously set datum level. When a second manual command is exercised the alarm is discontinued and a record of level is made and the datum level is reset to the existing level. The departure measuring means is reactivated to give an alarm signal upon sufficient departure of mud level from the new datum level.A third manual command makes a record and turns off the recorder while a trip is being made and until the third command controller is reset.

Abstract: Disclosed are apparatus and methods for detecting the extent to which material is present at a predetermined sensing area. An antenna probe is extended throughout the sensing area, and is loaded with a signal from an oscillator. A reference oscillator provides a constant-frequency signal of the same base frequency as the antenna oscillator signal. The presence of impedance-affecting material in the sensing area reduces the impedance load of the antenna and, therefore, the frequency of the output signal of the antenna oscillator in proportion to the extent of immersion of the antenna probe in such material. The output signals from both oscillators are compared in a frequency differencer circuit which produces output signals whose frequency, equal to the difference in frequencies of the two oscillator output signals, is an indication of the amount of material present in the sensing area.

Abstract: An ulrasonic liquid level measurement device is used to measure the depth of a flowing liquid in a channel using an ultrasonic transducer that is positioned out of contact with the liquid and above and directed toward the channel. An ultrasonic burst is directed toward the channel and the reflected echo from the surface of the liquid is returned and sensed by the transducer. The transit time of ultrasonic transmission and echo return is indicative of the liquid level. An adjustable discriminator is provided to specify a maximum liquid level in the channel and a minimum liquid level, which, typically is the floor of the channel. The maximum and minimum levels are adjustable to accomodate variable channel configurations and transducer mounting arrangements. Automatic adjustment is provided to compensate for different cable lengths which may be used to connect the ultrasonic transducer to the transducer driver and receiving section.

Abstract: A liquid level sensing device consists of an elongate member in which flexure waves are induced. By partially submerging the elongate member in a fluid the depth of immersion can be determined from characteristics of the flexure waves. In one mode of operation the transit time for a flexure wave to travel along the elongate member is measured, and in another mode the nature of resonant modes in the flexure wave is determined.

Abstract: A method and apparatus for identifying the fluid in a vessel, such as, a storage tank or pipeline using ultrasonic techniques. The method uses a transducer to project ultrasonic energy through the vessel and a second transducer positioned opposite the first to receive the energy that has been transmitted through the vessel and fluid. The transducers are included in a circuit whose parameters are adjusted to cause the circuit to resonate with the magnitude of the adjusted parameter being related to the fluid in the vessel.

Abstract: An improved sound ranging system increases the precision of range measurement by automatically correcting for any variation in the velocity of sound in the medium. The automatic correction for the sound velocity utilizes a small sound reflecting target located at a precise fixed distance from the transducer surface. A digital circuit, including a microcomputer, improves the measurement accuracy of the system. The invention includes a time delay and sensitivity control in one of the two time measurement circuits employed in the system to prevent "ghost" signals caused by multiple round-trip target reflections from introducing errors in the range measurements.

Abstract: A method and apparatus for determining a fluid condition adjacent an inner wall boundary of a fluid container is disclosed. A sonic pulse is applied to an outer wall boundary of the container wall and is reflected between an inner and the outer wall boundaries. The magnitude of the sonic pulse decreases each time it is reflected off of the inner wall boundary by an amount which varies as a function of the fluid condition adjacent the inner wall boundary. An electrical reflection pulse whose magnitude is representative of the instantaneous magnitude of the sonic pulse is generated each time the sonic pulse is reflected off of the outer wall boundary of the container. The electrical reflection pulses are integrated during an integration period so as to generate an integration output signal whose value varies as a function of the fluid condition within the container. The integration output signal is compared to a predetermined value to determine the fluid condition.

Abstract: An ultrasonic filling position limit switch having disposed in the container at the full level thereof, at least one ultrasonic transducer for sending out ultrasonic pulses and for receiving echo pulses reflected off the opposite container wall. An amplifier of the electric output signals of the transducer is connected to a threshold limit switch which provides an output signal when the amplifier output signal exceeds a predetermined threshold value. The amplifier output is fed back to an amplifier control input by means of an amplifier control circuit which seeks to maintain the amplifier output signal at an adjustable constant nominal value. A control device blocks the control circuit for the duration of time in each sending period required for the sending out of the ultrasonic sending pulses and for receiving the echo pulses.

Abstract: The present apparatus is designed to determine the presence of an intruder in a swimming pool by detecting a predetermined change in water level caused by displacement. The surface of the pool water forms the lower boundary of an air filled acoustic cavity, and cavity resonance is excited therein by a sonic transducer coupled to the cavity and also to a signal amplifier, causing the cavity to determine the frequency of oscillation of the feedback amplifier. A rise in water level caused by intruder displacement decreases the vertical dimension of the cavity so that the cavity has a different resonant frequency than before intrusion, and the amplifier therefore oscillates at a different frequency. The predetermined change in amplifier signal output frequency is sensed by an electrical network and converted to an alarm device activating signal to indicate an intrusion.

Abstract: A transceiver capable of transmitting and receiving ultrasonic signals for liquid level gauging, the elapsed time between the transmission of a pulse and the reception of an echo pulse reflected from the surface of the liquid being measured to afford an index of the level of the liquid. The transponder is constituted by a piezoelectric transducer assembly suspended within an open-ended casing by an electrically non-conductive elastomeric material which serves to rapidly damp the vibratory activity of the transducer to prevent ringing thereof which interferes with reception. In the assembly, the piezoelectric transducer is sandwiched between a loading plate and a horn-shaped radiating plate, the assembly being held together by a bolt which extends between the plates and passes through the transducer. The transducer operates in the compression mode and is therefore capable of operating reliably with a high voltage drive signal to cause the radiating plate to emit an ultrasonic beam having a narrow angle.

Abstract: An assembly and method for determining the level of sound absorbing solids in a fluid-filled vessel. A number of sound receivers are mounted at spaced vertical positions to the exterior of the vessel along a generally vertical line, and a sound generator is mounted atop the vessel approximately 180.degree. around the circumference of the vessel from the receivers. The sound waves are intermittently or cyclically generated by the sound generator, they are received by the receivers, and evaluated. For those receivers mounted below the level of the solids, the energy received will be low, while for those mounted above the solids level in the fluid phase of the vessel, the energy received will be high. For cellulosic chips, the receivers are tuned to respond primarily to sound at a frequency of about 3200 Hz.

Abstract: The level measuring system measures a variable level within a sensing area containing a mass of material. A sensing probe is positioned within the area and is coupled to the tank of an oscillating circuit through a switching network. A reference probe positioned in or near the sensing area is also coupled through the switching network to the tank of the oscillating circuit. The frequency of oscillation will depend upon a physical parameter of the mass of material within the immediate vicinity of sensing probe. Environmental conditions affecting the reactance of the sensing probe will equally affect the reference probe and therefore a change in the frequency produced by the sensing probe relative to the frequency produced by the reference probe will provide a true indication of the physical parameter being measured. Signal processing means are coupled to the oscillator for processing this frequency change.

Abstract: A method and apparatus for indicating the level of liquid in a tank or the like whereby a transducer is mounted on a pipe above the liquid for producing, in response to a trigger signal, an ultrasonic pulse which is transmitted toward and reflected to the transducer first from a calibration target in the pipe above the liquid and then from the liquid so that the transducer produces echo pulses in response to receipt thereof. In one embodiment the calibration echo signal is applied to a logic circuit together with the output of a counter which is incremented to a predetermined count following the trigger signal by pulses from a voltage controlled oscillator so that the logic produces a control signal indicating the difference in time between when the calibration echo is received and when the counter reaches its predetermined count and which event occurs first. The logic then varies the frequency of the oscillator to reduce the difference.

Abstract: An acoustic height sensor, particularly adapted for use in the foil-borne mode of operation of a hydrofoil, wherein sensitivity to noise pulses is materially reduced or essentially eliminated by monitoring for noise levels capable of producing interference and, if the noise persists for a sufficiently long period, suspending processing of any signal returns until the noise ceases. In the meantime, and as processing of signal returns is suspended, sample and hold circuitry maintains the output of the system at its previous level until the noise abates.

Abstract: An accurate measurement of the level of drilling mud in a mud pit is provided using an ultrasonic transducer that includes ambient temperature correction. A cylindrical metal shroud open at the bottom is positioned around the transducer. A series of vent holes are located along the upper area of the shroud to allow the convection of ambient air. A series of Nylon screws extend through the shroud close to the transducer to limit lateral movement of the transducer within the shroud. As the shroud and transducer become heated by sunlight, ambient air is circulated from the surface of the drilling mud upward to the transducer through the space between the transducer and the sidewalls of the shroud and out through the vent holes. The chimney effect thus produced insures that the temperature correction accurately represents the temperature of the ambient air between the drilling mud and transducer.

Abstract: A copy machine having a decorator for applying toner to a latent image is disclosed. The decorator is fitted with a control for sensing the level of toner in the decorator sump which control automatically maintains the amount of toner in the sump at the desired level. The control includes a toner level sensor which is a vibrating rod driven by a decorator roll.

Abstract: The invention relates to ultrasonic apparatus for measuring flow quantities and related parameters of a liquid flowing with a free surface in a channel. Two transducers are provided with one being mounted in the channel below the level of the flowing liquid. The other transducer is mounted on a float member which is floatable on the surface of the liquid. The transducers are effectively positioned from each other and a measuring path is formed therebetween which has components in the vertical direction and in the direction of flow. There is a measuring circuit for determining the transit times of the ultrasonic waves in both directions and an evaluating circuit for determining the desired quantities with regard to the transit times.

Abstract: The invention relates to ultrasonic apparatus for measuring flow quantities and related parameters of a liquid flowing with a free surface in a channel. Two transducers are mounted in longitudinally spaced relation to each other in the channel and below the level of the flowing liquid. The transducers are positioned and directed so that the effective measuring path therebetween is reflected from the underside of the liquid surface level and has components in the vertical direction and in the direction of flow. There is a measuring circuit for determining the transit times of the ultrasonic waves in both directions and an evaluating circuit for determining the desired quantities with regard to the transit times.

Abstract: An ultrasonic level measuring system is disclosed for determining by a time-ratioing technique the level of a liquid within a storage tank. An instrument sensor assembly, including a waveguide formed of a tensioned, ferromagnetic wire having a low thermoelastic coefficient is vertically supported within a storage tank containing a liquid. The waveguide is positioned to span both the tank liquid and vapor spaces. Two permanent magnets are positioned in close proximity to the waveguide at a known dimensional separation which defines the calibration span of the system. The waveguide and magnets are housed in a protective shield which acts as a process barrier and which is convoluted over a substantial portion of its length allowing the instrument sensor assembly to be easily transported and installed. A float, housing a permanent magnet, is positioned concentrically about the instrument sensor assembly to rise and fall with the liquid level.

Abstract: A system for the automatic measurement of the level of material in a container and especially of liquid flowing through a channel is described. An echolocation system operates to detect returns of reflected sonic signals from the surface of the liquid in the channel during successive transmission cycles. A source of pulses is provided having a frequency which provides a certain number of pulses corresponding to the travel time of the sonic signals over a distance equal to a maximum predetermined level or head of the liquid in the channel. The time interval between signal transmission and reception in excess of twice the time for travel of the signals between the transmitter and the maximum level of liquid is a measurement of the liquid level in the channel.

Abstract: In an ultrasonic antenna assembly specifically adapted for use in a material level control system and of the type which includes a parabolic reflector and an ultrasonic energy source mounted at the parabolic focus and directed to radiate energy toward the reflector surface from the direction of the parabolic axis, the improvement comprising a sonic absorber of low-density fiberglass disposed at the reflector surface opposite the energy source to absorb energy directed onto said surface from said source, such that multiple reflections between the energy source and the reflector surface are inhibited.In a modified embodiment the parabolic reflector and energy source are adapted to be mounted in the upper portion of a storage tank such that the parabolic axis is substantially horizontal, and a plane reflector is disposed adjacent the parabolic reflector at an angle of forty-five degrees with respect to the parabolic axis.

Abstract: The presence or absence of liquid at a particular location of a tank or pipe is sensed through the wall of the container by a single ultrasonic transducer which may be secured to the outer surface of the container by hand pressure, by clamping, or by cementing. Detection is obtained through the damping effect of either liquid or air within the container on multiple interface reflections of a longitudinal sonic beam in the container wall. The first return signal amplitude adjusts the gain of the monitoring circuit and allows the measurement of the percentage decay of the return signal and the comparison of the decay to the known decay rate if the container was either empty or full at the point of measurement. Output circuits are provided to give a full or empty output signal, or to provide output control signals in response to the fluid level measurement. A fault alarm signal is also produced to indicate that the transducer is not properly coupled to the container or that the circuit is working improperly.

Abstract: This invention relates to an ultrasonic flow meter utilizing a conventional tubular member with an inlet and outlet. An ultrasonic transducer is located in the member to transmit and receive ultrasonic energy through liquid flowing through the member. An energizing means is connected to the transducer so that ultrasonic energy can be transmitted through the liquid in the member. Reflector means variably positionable within the member are provided for establishing a position for the reflector means which is proportional to liquid flow rate through the member and for reflecting ultrasonic energy from the transducer back to the transducer. Control means are provided for producing at least a single pulse of ultrasonic energy from the transducer to be transmitted through the liquid and for detecting an echo pulse reflected from the reflector means.

Abstract: An ultrasonic transducer for a system for determining liquid levels by echo ranging composed of a housing including a piezoelectric crystal mounted within the housing to transmit acoustic waves, an impedance matching medium mounted within the housing adjacent the crystal and including a window layer and a diaphragm layer to transmit acoustic waves between the crystal and a gaseous environment which window layer is composed of a material having hollow glass spheres dispersed therein, and a dampening backing mounted in said housing to abut the crystal which backing includes a plurality of solid lead spheres; a tube mounted to extend from the housing to form a beam of acoustic waves propagated from said crystal, the tube having an end which is telescoped into the housing and spaced a short distance from the diaphragm to form a gap for flow communication; and a reference reflector assembly mounted to extend from adjacent said housing, which assembly includes a U-shaped member having two legs extending in slideabl

Abstract: An apparatus for measuring water depth comprising a range discrimination circuitry and an indication circuitry. The range discrimination circuitry includes a unit pulse generator, digital counters and digital gates. The indication circuitry includes a latch circuit, BCD-to-decimal decoders and indication lamps.

Abstract: A method of controlling gas-liquid or liquid-liquid interface in monolayer reservoirs, wherein mechanical vibrations are excited within a section of the reservoir wall by means of a wave of acoustic vibrations, the velocity of propagation of mechanical vibrations being approximately equal to that of the wave wake of acoustic vibrations along this wall, the interface being ascertained from the amplitude of the acoustic wave transformed from said mechanical vibrations which propagate along said reservoir wall. A device for performing said method consists of two sound conductors with effective areas, an emitter of the wave of acoustic vibrations and a receiver of an acoustic wave being established on said effective areas respectively.

Abstract: A method of measuring a filling level in a container or the height of loose material over a storage surface, comprises transmitting and recording a sound pulse having a duration at least as long as a pulse which travels to the lowermost level of the material, recording the echo of the sound pulse from the actual material filling level, and measuring, as a measure of the filling level, the time interval between the end of the transmitted pulse and the end of the echo pulse. A device for measuring the height of the filling material on a surface, comprises an electroacoustic transmitting transducer excited by an electric pulse generator and having a receiving transducer whose output is connected to an electrical time measuring device.

Abstract: A level detector is disclosed for detection of whether or not the level of the contents in a container, such as powder, grains, or liquid, attains a predetermined one. Said detector includes a coil and a vibrating plate consisting of a magnetic material or having a magnetic portion which plate is disposed in such a manner that the surface of said vibrating plate is nearly flush with that of the inner wall surface of said container. Said vibrating plate is vibrated by a coil disposed oppositely to said vibration plate and a drive unit to supply a pulse current to said coil. A mechanical vibrating-electric converter which is mounted on said vibrating plate converts the vibrations of said plate caused by said pulse currents into electric signals, and a sensor detects any differences in the amplitude between said electric signals detected when said contents are in contact with said vibrating plate or when said contents are not in contact with said vibrating plate.

Abstract: An acoustic echo-sounder arranged to determine the level of a substance in a container. The echo-sounder includes an acoustic transducer fitted to one end of an acoustic wave-guide, the acoustic impedance of which is progressively matched to the acoustic impedance of the space containing the substance in order to avoid disturbing reflections. In a preferred embodiment, the end portion of the acoustic wave-guide is constructed so that its solid cross-section diminishes progressively towards the end of the wave-guide.

Abstract: An acoustic tube having several resonant frequencies is directed into the mouth of a rafining crucible and is heated to above 100.degree. C. A microphone at the remote end of this tube receives sound passing through the tube and generates an electrical output corresponding to the sound received. This electrical output is linearized over a band width including several of the resonant frequencies of the tube and the signal is then passed through a low pass filter to eliminate parasitic oscillations and through a mixer where it is combined with a signal from a local oscillator. The intermediate-frequency signal thus produced is passed through either of a pair of band-pass filters and is displayed. The signal strength at the output is inversely proportional to the depth of slag in the crucible, as the deeper the slag the more sound is absorbed in the crucible.

Abstract: A device is disclosed for measuring the level of water comprising a hollow, oblong structure with an open end extended into the water, signal sending and receiving means secured onto the structure, an insert containing a hole secured within the structure, and electronic means connected to the signal sending and receiving means to receive and evaluate technical information in order to determine the level of the water.

Abstract: An ultrasonic sensing device for sensing the presence or absence of a liquid at various predetermined levels, especially in storage tanks, bilges and the like, employing multiple high frequency transducer assemblies having transmitting and receiving means enclosed in a sound conductive, e.g. metallic housing of special design minimizing "cross-talk" associated with means responsive to signals received above a selected minimum response level, the system being characterized by an on-off response provided by signal attenuation to a value less than said minimum response level in the absence of the liquid.

Abstract: A liquid level sensing system comprises a permanent magnet mounted in a cylindrical supporting case disposed in a housing and provided with a resistance plate at one end thereof, a reed switch arranged parallel to the permanent magnet and electromagnetic means including an iron core and a coil arranged above the supporting case and on the same axis as the permanent magnet. When the level of the engine oil goes down, the reed switch and the electromagnetic means cause the permanent magnet to vertically vibrate in the supporting case in the axial direction thereof thus causing for example a lamp to flash on and off and indicate the existence of an irregularity. With the construction described above, the system of this invention is capable of sensing an abnormal deterioration of the engine oil in addition to the sensing of the engine oil level.

Abstract: A vibratory system is provided on a wall member of a receptacle. The vibratory system comprises inner and outer rod elements projecting transversely from the inner and outer sides of the wall member and secured thereto, as by an internal screw stud with the axes of the rod members substantially aligned. Vibrations are induced in the outer rod element by an electromagnet having a coil which is supplied with low frequency electrical pulses. The magnitude of such vibrations is sensed by sensing the electrical signals induced in the coil due to such vibrations. A biasing magnetic flux is produced between the electromagnet and the outer rod element so that the vibrations produce variations in the magnetic flux. The electrical pulses supplied to the coil are at a substantially lower frequency than the natural vibration frequency of the outer rod element.

Abstract: Ultrasonic pulses are transmitted from the top of a tank or bin by a transducer and reflected by the material contained therein and received by the same transducer. In the short range mode, two millisecond pulses at sixty second intervals provide a measurment of from two to twenty one feet. Failure to detect a reflected pulse in the short range mode automatically switches the device to the long range mode utilizing ten millisecond pulses at three hundred millisecond intervals. After a pulse is transmitted the energy received by the receiver is converted to a digital value each millisecond and compared to the highest previously converted digital value so that the time of the largest received reflection signal and consequently the distance to the material surface may be determined.

Abstract: An ultrasonic acoustic pulse echo ranging system for monitoring the depth of liquid in a tank has transmitter and receiver transducers for mounting side-by-side in an upwardly directed disposition and exposed to the liquid at a datum level. A transmitter and receiver are adapted for coupling to the transducers from outside the tank. The transmitter includes an ultrasonic frequency oscillator for energizing the transmitter transducer to transmit acoustic pulses of the ultrasonic frequency, a gate to start the oscillator, a continuously cycling counter coupled with and effective to actuate the gate to start the oscillator at the start of each counting cycle, a regulator to stop the oscillator to determine the length of each transmitted acoustic pulse in terms of the number of cycles of the ultrasonic frequency in the pulse. The receiver is arranged to detect outputs from the receiver transducer and to generate output pulses in response to echoes of the acoustic pulses from the free surface of the liquid.

Abstract: Apparatus for measuring the level of a substance in a container of substantial depth which is practical, efficient, and rugged. Sonic or acoustic waves are transmitted through relatively sonic-wave propagating members, from an emitter member immersed in the substance whose level is to be determined to a collector also immersed in that substance. For this purpose, a sonic generator applies waves to an emitter portion of the wave-propagating means, and a collector portion of the wave-propagating means collects such emitted waves and applies them to a detecting means for producing indications of the level of the substance. The detecting means provide such indications on the basis of the relationship between the emitted and collected waves. The emitter and collector are each in the form of a rigid member capable of longitudinal wave propagations and are of substantially U-shaped horizontal cross-section.

Abstract: For supervising the filling level in an elongated space, such as hoppers, shafts, silos and the like, for miscellaneous granular material, the movement of the material is transformed into vibrations and the vibrations are converted into indicating signals which indicate the filling level. This may be accomplished by a plurality of rods which extend through the wall of the space and are subjected to the vibrations produced by solid materials falling through the space. This may be done by providing rods which extend beyond the wall into the space, and by accelerometers or the like which detect the vibrations and convert them into electrical signals which may control the discharge from the shaft.