Abstract: Piezoelectric sensor controllers may facilitate detection and identification of various potential fault states including noise-induced sensor blindness. In one illustrative embodiment, a sensor controller includes: a transmitter to drive a piezoelectric element during actuation intervals to generate acoustic bursts; a receiver to sense a response of the piezoelectric element to echoes of each acoustic burst, the receiver including a front-end amplifier; a processing circuit coupled to the transmitter and to the receiver, the processing circuit operable to apply echo-detection processing to said response; and a blindness detector to detect saturation of the front-end amplifier during or prior to the measurement intervals.

Abstract: An ultrasound device, including a profile generator, an encoder configured to receive a profile signal from the profile generator, and an attenuator configured to receive a signal representing an output of an ultrasound sensor and coupled to the encoder to receive a control signal from the encoder, the attenuator including a plurality of attenuator stages, the attenuator configured to produce an output signal that is an attenuated version of the input signal.

Abstract: According to one embodiment, an ultrasonic diagnosis apparatus includes an ultrasonic probe, transmission unit, reception unit, control unit, adjustment unit, automatic setting unit, switching unit, manual setting unit, correction unit, and generating unit. The adjustment unit adjusts transmission/reception conditions for repeated ultrasonic transmission/reception in accordance with an instruction from the user. The automatic setting unit sets the first gain for correcting an echo signal in accordance with the adjusted transmission/reception conditions. The switching unit switches between activating and stopping the operation of the automatic setting unit. The manual setting unit sets the second gain for correcting an echo signal in accordance with an instruction from the user. The correction unit corrects an echo signal with the first or second gain.

Abstract: A method is provided for calibrating a sensor used for surface weight measurement or thickness measurement on a material sheet via transmission measurement and/or reflection measurement. The method may include: providing a two-dimensional calibration sample with a known surface weight; detection of the transmission values and/or the reflection values of the calibration sample via the sensor on a plurality of different positions two-dimensionally or areally distributed across the surface of the calibration sample; and the detection of the calibration value for the sensor via calculation of average from the plurality detected transmission values and/or reflection values and the composition of the average transmission and reflection values with the known surface weight of the calibration sample.

Abstract: A fluid transfer apparatus includes a fluid transfer probe, a fluid level detection system, and a tip detection system. The fluid level detection system is configured to detect contact by the fluid transfer probe with a fluid surface within a receptacle from a signal based on the capacitance of the fluid transfer probe. The tip detection system is configured to detect the presence or absence of a tip at a distal end of the fluid transfer probe from a signal based on the capacitance of the fluid transfer probe.

Abstract: A device is disclosed that, in an illustrative embodiment, includes an input line, a main gain component, a first local gain component, and a second local gain component. The main gain component, the first local gain component, and the second local gain component each have a communicative connection with the input line. The main gain component is configured for applying a main gain to an ultrasonic wave signal received via the input line, thereby providing a main gain signal. The first local gain component is configured for applying a first local gain to a portion of the ultrasonic wave signal within a first signal gate, and thereby providing a first local gain signal. The second local gain component is configured for applying a second local gain to a portion of the ultrasonic wave signal within a second signal gate, and thereby providing a second local gain signal.

Abstract: Actual ultrasound attenuation in tissue is used to calculate gain compensation profiles which are used to create a uniform image. Axial, lateral, elevation gain profiles are used to correct the attenuation and ultrasound variation in each direction. In addition, automatic activation of the automatic gain compensation is described.

Abstract: The present invention provides an ultrasound system, which comprises: a signal acquiring unit to transmit an ultrasound signal to an object and acquire an echo signal reflected from the object; a signal processing unit to control TGC (Time Gain Compensation) and LGC (Lateral Gain Compensation) of the echo signal; a TGC/LGC setup unit adapted to set TGC and LGC values based on TGC and LGC curves inputted by a user; and an image producing unit adapted to produce an ultrasound image of the object based on the echo signal. The signal processing unit is further adapted to control the TGC and the LGC of the echo signal based on the TGC and LGC values set by the TGC/LGC setup unit.

Abstract: Actual ultrasound attenuation in tissue is used to calculate gain compensation profiles which are used to create a uniform image. Axial, lateral, elevation gain profiles are used to correct the attenuation and ultrasound variation in each direction. In addition, automatic activation of the automatic gain compensation is described.

Abstract: A gain control method for B-mode ultrasonic imaging, a gain control module, and a B-mode ultrasonic imaging system are disclosed.

Abstract: The present invention relates to an ultrasound imaging device. The ultrasound imaging device includes: a data acquiring unit for acquiring 3-dimensional ultrasound image data based on receive signals formed based on ultrasound echoes reflected from a target object; a filtering unit for determining a size of a filtering mask of a filter, said size being adaptively determined according to an amount of the 3-dimensional ultrasound image data in data acquisition directions, the filtering unit being further configured to filter the 3-dimensional ultrasound image data by using the filtering mask; a scan converting unit for scan-converting the filtered 3-dimensional ultrasound image data; and a 3-dimensional rendering unit for performing 3-dimensional rendering upon the scan-converted 3-dimensional ultrasound image data to form a 3-dimensional ultrasound image.

Abstract: The present invention provides an ultrasound system, which comprises: a signal acquiring unit to transmit an ultrasound signal to an object and acquire an echo signal reflected from the object; a signal processing unit to control TGC (Time Gain Compensation) and LGC (Lateral Gain Compensation) of the echo signal; a TGC/LGC setup unit adapted to set TGC and LGC values based on TGC and LGC curves inputted by a user; and an image producing unit adapted to produce an ultrasound image of the object based on the echo signal. The signal processing unit is further adapted to control the TGC and the LGC of the echo signal based on the TGC and LGC values set by the TGC/LGC setup unit.

Abstract: A method and apparatus for effecting ultrasonic flaw detection of an object processes an echo signal received from the object being tested in at least three signal channels, wherein the echo signal is scaled to different degrees along each channel to increase and extend the dynamic range of an associated A/D converter system, in a manner which dispenses with the need for using numerous analog high pass and low pass filters and a variable gain amplifier. This reduces complexity and avoids performance limitations. The digital to analog converters sample the differently scaled input signal and a selection circuit selects the output of the digital output obtained from that analog to digital converter which has the highest gain, but which has not overflowed. The digital outputs are seamlessly merged to produce an output that can be displayed as a scan display which shows the location of faults.

Abstract: A method and apparatus for effecting ultrasonic flaw detection of an object processes an echo signal received from the object being tested in at least three signal channels, wherein the echo signal is scaled to different degrees along each channel to increase and extend the dynamic range of an associated A/D converter system, in a manner which dispenses with the need for using numerous analog high pass and low pass filters and a variable gain amplifier. This reduces complexity and avoids performance limitations. The digital to analog converters sample the differently scaled input signal and a selection circuit selects the output of the digital output obtained from that analog to digital converter which has the highest gain, but which has not overflowed. The digital outputs are seamlessly merged to produce an output that can be displayed as a scan display which shows the location of faults.

Abstract: A method and apparatus for effecting ultrasonic flaw detection of an object processes an echo signal received from the object being tested in at least three signal channels, wherein the echo signal is scaled to different degrees along each channel to increase and extend the dynamic range of an associated A/D converter system, in a manner which dispenses with the need for using numerous analog high pass and low pass filters and a variable gain amplifier. This reduces complexity and avoids performance limitations. The digital to analog converters sample the differently scaled input signal and a selection circuit selects the output of the digital output obtained from that analog to digital converter which has the highest gain, but which has not overflowed. The digital outputs are seamlessly merged to produce an output that can be displayed as a scan display which shows the location of faults.

Abstract: Diagnostic ultrasound flow imaging is performed with coded excitation pulses. Due to the use of frequency coded excitation pulses, flow information may suffer from spatial misregistration and estimate errors. Spatial position shift in flow data is offset for alignment with B-mode or other imaging. The flow estimates are compensated for the imaging center frequency variation with depth. The wide bandwidth information available due to coded excitation may allow anti-aliasing by estimating velocities from two frequency bands.

Abstract: The present invention relates to an image processing system for enhancing the image quality of an ultrasound image.

Abstract: Disclosed are an apparatus and method of adjusting gain of an ultrasound system 100. In particular, subject matter is disclosed for receiving an indication 102 of a rate of change in motion of an object 106, and adjusting a gain based 108, at least in part, on said rate of change in motion, where the gain is adjusted at least partially corresponding to the rate of change in motion of the object 106.

Abstract: A system and method for range dependent weighting in ultrasound imaging. The system includes a transducer array, a data acquisition system, and an imaging processor. The transducer array receives a first ultrasound beam having a first focal depth. The data acquisition system receives a first ultrasound imaging signal from the array. The first signal includes first image data based on at least the first ultrasound beam. The imaging processor combines a first data contribution from the first image data with at least second image data from a second ultrasound imaging signal to create a spatially compounded image. The first data contribution is based on at least the focal depth of the first beam.

Abstract: Systems and methods are described that carry out an intelligent, variable, time-gain control (TGC) of signal amplification in a long-range, guided-wave inspection and monitoring system. The systems and methods compensate for signal attenuation over the longer distances that guided-wave inspection techniques are capable of operating with. The sensor signal received is divided into relevant frequency bands that are each subjected to a variable TGC through separate variable gain amplifiers (VGAs). The gain selection is processor controlled through the use of a digital look-up table (LUT) stored with predetermined gain functions and/or data that are both time and frequency specific. The signal components are re-combined and digitized for further signal analysis and defect detection. The LUT is established through one or more methods including a weld signal amplitude equalization approach and a background noise equalization approach.

Abstract: Methods are provided for automatic setting of parameters for contrast agent quantification. Various processes may improve quantification. For example, for consistency in contrast agent quantification, a gain or other setting of an ultrasound system is automatically determined in response to destruction of the contrast agent or at the initiation of the contrast agent quantification procedure. Automatic setting of an adaptive gain provides equalized image intensity for each repetition of a contrast agent quantification procedure based on a same triggering event, the destruction of contrast agent. By synchronizing the adaptive setting algorithms with contrast agent destruction, similar base line information is provided for each iteration of a contrast agent quantification procedure. As another example, the contrast agent gain setting treats acoustic signals representing tissue or other non-contrast agent structure as noise, mapping the tissue values to a substantially constant low value within the dynamic range.

Abstract: A system and method for inspecting a structure having a coating on at least one surface are provided. The system includes at least one ultrasonic sensor positioned proximate to the structure. Each sensor is capable of transmitting a shear wave toward the structure and receiving return signals in response thereto, wherein the shear wave includes at least one reference beam and at least one interrogating beam. The system further includes a data acquisition system in communication with the sensor for generating information indicative of the coating based on at least one return signal associated with the reference beam.

Abstract: The systems and methods described herein provide for automatic time-gain compensation of an ultrasound image with an image processing algorithm. A method of automatic time-gain compensation is provided where ultrasound image data is obtained comprising a plurality of echogenic data sets, a plurality of time-gain compensation functions are determined for the plurality of echogenic data sets, wherein each time-gain compensation function is determined from a separate echogenic data set and the time-gain compensation functions are applied to the plurality of echogenic data sets automatically without user intervention. Also provided is an ultrasound imaging system having an ultrasound imaging device configured to collect ultrasound image data and an image processing system configured to automatically time-gain compensate the collected image data.

Abstract: A method for determining incipient mechanical failure of an object includes insonifying the object with ultrasonic energy at a selected fundamental frequency. Amplitude data is acquired from the insonified object at the fundamental frequency and at a second harmonic of the fundamental frequency, and a non-linear acoustic image is generated from the amplitude data at the fundamental frequency and the second harmonic frequency.

Abstract: A noncontact physical property measurement instrument which easily and accurately measures physical properties of an object using a nondestructive, noncontact sensor. A noncontact physical property measurement instrument 1 is provided with a transmitting section 21 and a receiving section 22. The transmitting section 21 sends a wave to an object 41 in a medium 100, and the receiving section 22 receives a wave reflected from the object 41 and the surface of a coating 42. Both the transmitting section 21 and the receiving section 22 are connected to a gain change correction circuit 13 to form a self-excited oscillating circuit 11 serving as a feedback loop. The gain change correction circuit 13 corrects the gain to the increase side according to a phase difference between the sent wave and the reflected wave, to thereby measure any changes due to a difference in physical properties of the object 41.

Abstract: An ultrasonic diagnostic imaging system includes a predetermined TGC characteristic which is automatically selected or calculated at the initiation of a diagnostic procedure. An automatic TGC circuit analyzes current image data to calculate an adjustment to the predetermined TGC characteristic when activated by the clinician. The ultrasound system produces a displayed TGC curve which illustrates the predetermined TGC characteristic as modified by automatic adjustment and any manual refinement done by the clinician. In a preferred embodiment automatic TGC modification is accompanied by automatic overall gain and dynamic range adjustment to automatically optimize image quality.

Abstract: The gain for multiple mode imaging and/or contrast agent imaging is automatically adjusted. The gain algorithm separately determines gain parameters for two different types of imaging, such as tissue and contrast agent imaging. The gain based on the contrast agent image may be optimized to provide maximum sensitivity, such as by mapping noise values measured prior to injection of contrast agent to low values within the dynamic range or somewhat below the display dynamic range. The automatic gain based on the contrast agent image may be free of variance calculations. One of the two gain parameters is selected as the system gain, or the two gain parameters are combined to form the system gain. The presence of contrast agents within the image may be determined, and different gain parameters used based on the presence or absence of contrast agents. Various ones or combinations of the gain adjustments summarized above may be used.

Abstract: An end effector for supporting an ultrasonic testing probe on a robot arm having a robot mounting bracket for use in a nuclear reactor pressure vessel. The end effector has a wrist assembly with a rotatable wrist axle. The wrist assembly is coupled to the robot mounting bracket and a probe assembly is coupled to the wrist shaft. The ultrasonic testing probe is floatably disposed within the probe assembly.

Abstract: A medical ultrasonic imaging system uses an adaptive multi-dimensional back-end mapping stage to eliminate loss of information in the back-end, minimize any back-end quantization noise, reduce or eliminate electronic noise, and map the local average of soft tissue to a target display value throughout the image. The system uses spatial variance to identify regions of the image corresponding substantially to soft tissue and a noise frame acquired with the transmitters turned off to determine the mean system noise level. The system then uses the mean noise level and the identified regions of soft tissue to both locally and adaptively set various back-end mapping stages, including the gain and dynamic range.

Abstract: The front-end gain of a medical diagnostic ultrasonic imaging system receiver is adaptively set by acquiring receive samples that vary in range, generating a gain function that varies in range as a function of envelope amplitude of the receive samples, and then controlling the front-end gain with the gain function. In this way, front-end gain is set in accordance with the currently prevailing imaging conditions, and front-end gain that is excessively high or low is avoided. Transmitter gain is adaptively set to limit or prevent front-end gain saturation of the receiver.

Abstract: Method, apparatus and computer programs are described for compensating for the effect of temperature on the sensitivity of electrostatic ultrasound (US) transducers, particularly as used in an automotive occupancy sensing (AOS) systems for sensing the nature or type of occupant and the location of the occupant with respect to the vehicle interior. The invention permits the AOS to classify the occupancy state of the vehicle from a US echo signal substantially free of the effects of temperature on signal amplitude. A capacitive divider or voltage monitor is employed to measure the capacitance of the transducer. The voltage monitor output is used by the scaling algorithm of a compensator to determine the scaling factor to be applied to the US transducer signal to compensate for the effect of temperature on the transducer sensitivity.

Abstract: A nondestructive testing apparatus is provided with a wave transmitter by a metal-based magnetostrictive vibrator, a magnetically excited current feeding device for feeding the magnetically excited current to the magnetostrictive vibrator, a wave receiver for detecting an acoustic elastic wave propagating through the measurement object, a filter for extracting a signal in a target frequency band to be measured, and an automatically amplifying rate controlling function-equipped amplifier for automatically controlling the amplifying rate so as to obtain a given magnitude amplitude regardless of the magnitude of the reflection wave or the transmission wave detected by the wave receiver, which constitute a feedback loop.

Abstract: A medical diagnostic ultrasound imaging system and method modulate the image signal as a function of the ratio of the harmonic receive signal to the fundamental receive signal. Tissue harmonic backscatter differs substantially in spectral shape as compared to contrast agent backscatter, and this method allows improved discrimination between contrast agent and tissue backscatter.

Abstract: A diagnostic medical ultrasonic imaging system includes a gain processor that varies the receive signal path gain as a function of the signal to noise ratio of the echo signal. Background noise is either acquired or modeled in real time using currently prevailing imaging parameters, and acquired echo signals are compared with the acquired or modeled background noise values. The receive gain is controlled as a function of this comparison to improve the signal-to-noise ratio, and to reduce or prevent the amplification of echo signals that are not greater than the background noise level.

Abstract: The present invention includes a fully programmable plurality of multi-channel receivers, each receiver having a digital multi-channel receive processor and a local processor control. Each receive processor includes a first decimator, time delay memory, second decimator, and complex multiplier. The receive beamformer is a computationally efficient system which is programmable to allow processing mode trade-offs among receive frequency, receive spatial range resolution, and number of simultaneous beams received. Each local control receives focusing data from a central control computer and provides final calculation of per-channel dynamic focus delay, phase, apodization, and calibration values for each receiver signal sample. Further, this invention includes a baseband multi-beam processor which has a phase aligner and a baseband filter for making post-beamformation coherent phase adjustments and signal shaping, respectively.

Abstract: An ultrasonic rangefinder capable of effectively removing high-level, directly transmitted wave components. The rangefinder can be used even at low temperatures. The rangefinder comprises an input signal-processing circuit, an output signal-processing circuit, and a gain control circuit inserted between the input and output signal-processing circuits. The output signal-processing circuit includes a reception amplification circuit and a detection circuit, the reception amplification circuit having an amplifier. The gain control circuit lowers the gain of the reception amplification circuit to raise the undetected and detected input voltage levels applied to the detection circuit. The gain control circuit comprises three control devices. The first control device is driven into conduction when its input pulse signal varies from a low level to a high level.

Abstract: An ultrasonic image processing for accurately detecting the annulus portion from the ultrasonic image of the long axis view of a heart. A heart wall contour is extracted from the ultrasonic image, and a center of gravity of the heart wall contour is determined. Then, for an image imaged from an apex portion side, the annulus portion is detected from points on the heart wall contour located at positions deeper than the center of gravity, whereas for an image imaged by a transesophageal echocardlography, the annulus portion is detected from points on the heart wall contour located at positions shallower than the center of gravity.

Abstract: The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part.

Abstract: The invention includes a method and system for automatic gain compensation in an ultrasound imaging system. The method and system may be used in place of, or in addition to, gain compensation selected by an operator. Gain compensation may be in response to range, in response to cross-range, or in response to both. Ultrasound imaging data is partitioned into relatively small zones (such as regions selected in response to range and cross-range), and a zone intensity value representative of each zone is used to determine information, such as an average image intensity, about ultrasound signals reflected from objects being imaged in each zone. The zone intensity value can be determined during real-time image acquisition by special-purpose averaging hardware, so that a commercial programmable microprocessor may operate on the zone intensity values to generate a gain compensation curve, also in real-time.

Abstract: Ultrasonic wave converged by an acoustic lens is made incident onto a sample and wave reflected from the sample is received and converted into received electric signal by a transducer. A part of this electric signal is picked up by a gate section and the signal thus picked up is applied to an attenuator where it is converted into a variable ratio of input to output. The strength of the signal thus gain-adjusted is compared with a threshold value by a comparator. Responsive to the comparison result thus obtained, the gain of the attenuator is adjusted to make the input/output ratio of the attenuator a desired value. A computer calculates the focus position of the acoustic lens from a gain curve of the attenuator changing when the acoustic lens is moved from a position, remote enough from its focus position, to the sample. Drivel signal responsive to the result thus calculated is applied to a Z-drive control section.

Abstract: In an ultrasonic measuring apparatus for emitting an ultrasonic pulse, receiving reflected echos and producing an echo signal representative of the echos resulting from each impulse, each echo signal has a first portion corresponding to echos from one group of interfaces and a second portion corresponding to echos from another group of interfaces. The apparatus comprises a gain control (24) for controlling the amplitude of each echo signal and a processor (26) for receiving and treating said echo signals.

Abstract: A method and apparatus for depth compensating the amplitudes of echo signals in an ultrasonic measuring device to compensate for virtually unlimited depth measurements using an amplifier adjustment curve supplied in real time which is triggered with every radiated pulse, and using the time-synchronous clock steps of a clock pulse generator converted to an analogue output signal through a D/A-converter.

Abstract: An ultrasound transducer apparatus for use with an ultrasound imaging system which includes signal transmission and signal receiving circuitry coupled to the transducer through a cable. The transducer apparatus includes a transducer for converting ultrasonic energy into electronic signals and a variable gain amplifier circuit having an input coupled to the transducer and an output coupled to the cable for amplifying the electronic signals at a gain determined by a gain control signal from the imaging system. The transducer apparatus is typically hand-held, and the variable gain amplifier circuit is preferably mounted in the hand-held unit in close proximity to the transducer element. The variable gain amplifier circuit preferably includes a preamplifier and a variable gain amplifier. Preferably, the transducer is a transducer array including a plurality of transducer elements, each having a preamplifier and a variable gain amplifier associated with it.

Abstract: An operator adjusted lateral gain control (LGC) structure for an ultrasound imaging system, which may already include an operator adjusted time gain compensation (TGC) gain control structure. The LGC structure enables an operator to adjust the gain of one or more scan lines independently of the gain of at least one other scan line, said gain as a result of the LGC control being substantially constant along said one or more scan lines.

Abstract: In an ultrasonic imaging system capable of generating conventional envelope detected acoustic data and/or integrated backscatter acoustic data, a mechanism is provided to select a plurality of pixels in a specified region of a two dimensional ultrasonic image. The pixel values are processed to compute the average acoustic intensity for the selected pixels. The average value is then processed to reverse any non-linearities between the calculated average value and the originally received acoustic signals which non-linearities may have been introduced by the compression, scaling and mapping of the data in order to display it on a conventional video monitor. The processed average acoustic intensity is plotted and the procedure repeated at specified time intervals to form a time-intensity curve whose characteristics are linearly related to the originally received acoustic signals.

Abstract: An apparatus for electrically blending echoes from a plurality of focused beams into a composite image having reduced image artifacts. The apparatus comprises a transducer generating a sequence of beams having different focal points and converting resultant echoes into electrical signals, a receiver with its gain adjusted according to (1) time and (2) the transmitted beam, a multiplier that develops the product of the receiver output and a gain selected both by the transmitted beam and (time), and a summing network that adds together outputs of the multiplier that originated from the same sound scatterer.

Abstract: A method and apparatus are provided for gain control in a Doppler or other scan system which projects a plurality of scan lines at a given angle to determine velocity of movement of a predetermined medium at the angle. A training line is generated at the angle of the scan lines, the training line being utilized to determine portions of the scan line which are in a flow medium of interest, such as blood, and portions of the scan line which are in clutter. Information from the training line is then utilized to control the gain of the scan lines so that the gain is substantially maximized when scan lines are in the flow medium, while being reduced so as not to saturate the system in general, and A/D converters in particular, when in clutter. When an image line is utilized in the system, this line may also function as the training line.

Abstract: The invention is a method of and apparatus for characterizing the amplitudes of a sequence of reflected pulses R.sub.1, R.sub.2, and R.sub.3 by converting them into corresponding electrical signals E.sub.1, E.sub.2, and E.sub.3 and thereafter exponentially adjusting the amplitudes of the respective signals E.sub.1, E.sub.2, and E.sub.3 to substantially the same value during each sequence thereby restoring the reflected pulses R.sub.1, R.sub.2, and R.sub.3 to their initial reflection values by means of timing means 12 and 13, an exponential generator 17 and a time gain compensator 18. Envelope and baseline reject circuits 23 and 24 respectively permit the display and accurate location of the time spaced sequence of electric signals having substantially the same amplitude on a measurement scale on a suitable video display or oscilloscope 14.

Abstract: An apparatus for determining the length of an open or closed-end pipe by measuring the propagation delay of a sound pulse transmitted down the pipe bore. The apparatus includes an acoustic transducer, an acoustic detector and associated circuitry for computing the time required for an acoustic pulse to travel and return the length of a pipe. Electronic circuitry, including a microprocessor, is employed to provide the apparatus with an automatic gain adjustment feature. The gain circuitry increases the amplification until a return pulse of desired amplitude is obtained. The gain is time varying to make the last-to-return signals strongest thereby avoiding false readings from pipe discontinuities. Compensation is made for speed-of-sound variations due to temperature, humidity, and barometric pressure by direct measurement of speed of sound during each length measurement. The open or closed endedness of a pipe is determined by return signal charateristics and a correction factor applied for open-ended pipe.

Abstract: The invention relates to a method for the automatic correction of the variations of efficiency of an electroacoustic transducer as a function of the frequency for improving the accuracy of a device measuring the thickness of layers of materials by ultrasonic interferometry.