Abstract: A method and system for monitoring fluid flow, such as fluid flow through pipelines or similar conduits for delivering natural gas, crude oil, and other similar liquid or gas energy commodities, relies on the measurement of acoustic waves generated by the fluid, thus allowing for monitoring of the flow rate without direct access to the fluid. Furthermore, the method and system allows for estimation of the operational dynamics of components or facilities of the production, transportation, storage, and distribution systems for the energy commodities.

Abstract: An ultrasonic signal processing method for improving the signal-to-noise ratio in ultrasonic measurements comprises the transmission of a predefined timed sequence of a number of ultrasonic burst signals at a first transducer, and reception of a signal representing said transmitted sequence of ultrasonic burst signals at a second transducer. This signal is processed by addition of multiple time-shifted copies of the received signal to said original received signal to obtain a sum of the original received signal and its time-shifted copies. An original burst signal having an improved signal-to-noise ratio is reconstructed from this sum.

Abstract: A method and apparatus for detecting contaminants in hydrocarbon fuel are disclosed, wherein a fuel analyzer includes a flow sensor to facilitate an automatic start up and shut down of a fuel analysis, and a calibration standard to facilitate an inline calibration of the fuel analyzer.

Abstract: A method for testing a unit is described where the unit includes one or more of electrical, electronic, mechanical, and electromechanical components. The described method includes applying at least one stimulus to the unit, receiving sound emissions from the unit, converting the sound emissions into one or more acoustic signatures, comparing the acoustic signatures based on the received emissions to stored acoustic signatures expected as a result of the at least one stimulus, and determining a status for the unit based on the comparisons.

Abstract: A circuit chip is disclosed. The circuit chip includes analog-to-digital processing circuitry that is capable of interfacing with a sensor and host electronics. The analog-to-digital processing circuitry includes a frequency generator configured for providing stimulus to the sensor and signal detection circuitry that is configured for identifying amplitude data of a response signal. Further included is analog-to-digital conversion circuitry that is configured for converting the detected amplitude data into digital form. A memory that is capable of holding data characterizing the sensor is also provided. The digital form of the response signal is capable of being processed to generate fluid characteristics of fluids under-test.

Abstract: A system and a method for screening of nucleation tendency of a molecule, such as a macromolecule, based on acoustic, electrostatic or hybrid acoustic/electrostatic levitation of a droplet for optimizing crystallization conditions for said molecule. This allows for a controlled approach to determination of supersaturation and allows for screening of crystal nucleation conditions within minutes and hours instead of months and years with a minute amount of starting material compared to conventional crystallization methods.

Abstract: An apparatus for measuring the viscosity and temperature of a fluid, for example an engine oil, comprises a transducer, which is arranged to vibrate when provided with a drive signal to produce an ultrasonic shear wave; an impedance matching layer that is inserted into the fluid and which couples at least a portion of the ultrasonic waves produced by the transducer into the fluid and from which at least a portion of the wave is reflected back to the transducer; a detector which is adapted to detect a measurement signal produced by the transducer when the reflected wave is incident upon the transducer; a control circuit which varies the frequency of the drive signal applied to the transducer and hence the frequency of the ultrasound signal; a processing means which determines the optimum frequency of the drive signal at which the measurement signal output from the transducer has its minimum amplitude; and a temperature determining means which estimates the temperature of the fluid as a function of the optimum

Abstract: Circuitry adapted for carrying out associated techniques for: (a) calculating a damping factor, e.g., a damping ratio represented by ?, or a quality factor Q, where ??1/2Q, for a transient signal received, having been emitted from a resonator-type sensor element; (b) determining amplitude, A, of the transient signal; or (c) generating a frequency response dataset of interrelated points for the transient signal. A threshold comparison circuit is included for converting the transient signal received into a first and second digital waveform; the first digital waveform represents cycle crossings of the transient signal associated with a first threshold value, and the second digital waveform represents cycle crossings of the transient signal associated with a second threshold value. The transient signal may be converted, likewise, into third, and so on, digital waveforms, whereby the third digital waveform represents cycle crossings of the transient signal associated with a third threshold value.

Abstract: A method, used in connection with a pulse-echo type sensor for determining the speed of sound in a gas, for improving the accuracy of speed of sound measurements. The sensor operates on the principle that speed of sound can be derived from the difference between the two-way travel time of signals reflected from two different target faces of the sensor. This time difference is derived by computing the cross correlation between the two reflections. The cross correlation function may be fitted to a parabola whose vertex represents the optimum time coordinate of the coherence peak, thereby providing an accurate measure of the two-way time diffference.

Abstract: A reduced order model called the Fundamental Mistuning Model (FMM) accurately predicts vibratory response of a bladed disk system. The FMM software may describe the normal modes and natural frequencies of a mistuned bladed disk using only its tuned system frequencies and the frequency mistuning of each blade/disk sector (i.e., the sector frequencies). The FMM system identification methods—basic and advanced FMM ID methods—use the normal (i.e., mistuned) modes and natural frequencies of the mistuned bladed disk to determine sector frequencies as well as tuned system frequencies. FMM may predict how much the bladed disk will vibrate under the operating (rotating) conditions. Field calibration and testing of the blades may be performed using traveling wave analysis and FMM ID methods. The FMM model can be generated completely from experimental data. Because of FMM's simplicity, no special interfaces are required for FMM to be compatible with a finite element model.

Abstract: The process measuring device includes a flow sensor having a measuring tube, a sensor arrangement for producing a measurement signal, and an evaluation and operating circuit. The method serves to compensate for the effects of interfering potentials which are caused especially by foreign particles or air bubbles in the liquid to be measured. For this purpose, an anomaly in the waveform of the measurement signal caused at least in part by an electrical, especially pulse-shaped, interfering potential is detected by determining within a stored first data set a data group which digitally represents the anomaly. To generate an interference-free data set, the data belonging to the data group are removed from the stored first data set.

Abstract: A remote sensor and associated data processor, performs concurrent analysis of backscattered signals from a multi-beam acoustic Doppler emitter/receiver positioned against the inside wall of a conveying pipe or channel. Range-gating of the return signals allows independent analysis of discrete volumes of backscattered signal data corresponding to the distribution, concentration and travel velocity of small individual volumes or bins of water and suspended solids. Velocity is derived from the measured Doppler frequency shift for each bin. Relative solids concentration is estimated as a function of the measured intensity of the backscattered signals.

Abstract: A method for locating two dimensional critical flow features on a surface of a three dimensional body immersed in a fluid stream is presented. The method includes applying a hot film sensor array on the surface of the body. The hot film sensor array includes a plurality of hot film sensor elements disposable in a two dimensional array over at least a portion of the body surface. Each sensor element is connected to an associated anemometer circuit to provide an output voltage. The method further comprises obtaining output voltage data for each hot film sensor element with the body immersed in the fluid stream under a set of flow conditions and processing the hot film sensor element output voltage data to locate at least one two dimensional critical flow feature on the body surface.

Abstract: Tracking vibrations on a pipeline network includes installing multiple vibration recorders on the pipeline network, with each recorder including a sensor, a timer, a processor, and a digital communication device. At each vibration recorder, vibration signals are received from the sensor at programmed times under the control of the processor of the vibration recorders and processed by the processor. The processed vibration signals are communicated from the vibration recorder to a reader device using the digital communication device. Thereafter, the processed vibration signals from the one or more reader devices are collected at a central computer system. Finally, the collected processed vibrations signals are analyzed at the central computer system to determine abnormal vibration patterns and to obtain measures of any leaks present in the pipeline network.

Abstract: Startup and operational techniques for a digital flowmeter are described. The techniques select an optimal mode of operation for the digital flowmeter, depending on a current environment of the flowmeter. For example, during a startup operation of the flowmeter, the mode of operation might include a random sequence mode, in which filtered, random frequencies are applied as a drive signal to a flowtube associated with the digital flowmeter. Once the flowtube reaches a resonant mode of vibration, the digital flowmeter may transition to a positive feedback mode, in which a sensor signal representing a motion of the flowtube is fed back to the flowtube as a drive signal, as part of a feedback loop. Once an oscillation of the flowtube is achieved and analyzed, a digital synthesis mode of operation may be implemented, in which the analyzed sensor signals are used to synthesize the drive signal.

Abstract: A method and apparatus for monitoring fluid flow in a pipe or at an exit of the pipe and detecting a fault. The system includes an acoustic generator which is activated by the fluid flowing in the pipe or at the exit of the pipe. The acoustic generator sends an acoustic signal, which may have a distinctive signature, through the fluid flowing in the pipe. The acoustic signal is received by a remote upstream acoustic receiver and is translated into an electric signal supplied to a signal processor.

Abstract: A Doppler type ultrasonic flowmeter has an ultrasonic transmitting means for emitting ultrasonic pulses from an ultrasonic transducer into a fluid pipe, a flow velocity profile measuring means for receiving an ultrasonic echo reflected from a measurement region in the fluid pipe thereby to measure a flow velocity profile of a fluid to be measured, a fluid flow rate computing means for calculating the flow rate thereof on the basis of the flow velocity profile of the fluid to be measured, and a frequency selecting and setting means for automatically selecting a fundamental frequency of an ultrasonic wave that causes a resonant transmission phenomenon to take place from the ultrasonic transducer. The frequency selecting and setting means controls the operation of the ultrasonic transmitting means such that an ultrasonic wave of a selected optimum frequency is emitted from the ultrasonic transducer.

Abstract: A method for detection of information on at least one optical element for monitoring an equipment, in which an electromagnetic radiation is shaped or guided by the at least one optical element, particularly for monitoring a laser arrangement. A change of at least one physical quantity in or on at least one optical element is detected with a measuring device by means of the absorbed electromagnetic radiation. At least one actual value detected by means of the measuring device is forwarded to an evaluation unit. At least one actual value is compared with a reference value deposited in the evaluation unit.

Abstract: The present invention provides a small, low power consumption ultrasonic flow velocity meter. The burst signal generation section 110 generates two kinds of burst signals with a phase difference and sends these burst signals to a pair of transmission/reception ultrasonic transducers 6 and 7 located on the upstream side and downstream side of the conduit to be measured 9. Upon reception of the corresponding burst signals, the pair of the transmission/reception ultrasonic transducers 6 and 7 convert the burst signals, send ultrasonic waves with a phase difference to the conduit to be measured 9, receive the ultrasonic wave sent by the other transmission/reception ultrasonic transducer and propagated through the conduit to be measured and convert the ultrasonic waves to received signals.

Abstract: A system is disclosed for use in assembling a plurality of rotatable elements in the assembly of a turbine engine. The system includes an initialization unit, a measurement unit, and a processing unit. The initialization unit is for entering initialization data into a database. The initialization data includes a first set of initialization data that is representative of characteristics of a first rotatable element, and a second set of initialization data that is representative of characteristics of a second rotatable element. The measurement unit is for permitting a user to enter measured data including a first set of measured data characteristic of measured features of the first rotatable element, and a second set of measured data characteristic of measured features of the second rotatable element.

Abstract: A system to monitor the integrity of a railway track is provided. The system comprises a mechanical signal source and a correlation detector. The mechanical signal source coupled to the railway track and is configured for generating a mechanical signal pulse train over the railway track. The correlation detector monitors the integrity of the railway track by observing the pulse trains transmitted by the mechanical signal sources. If the railway track is intact, then the pulse train will travel to the correlation detector and afford the opportunity for repeatable detection.

Abstract: Methods and systems for identifying, understanding, and predicting the degradation and failure of mechanical systems are disclosed. The methods include measuring and quantifying stressors that are responsible for the activation of degradation mechanisms in the machine component of interest. The intensity of the stressor may be correlated with the rate of physical degradation according to some determinable function such that a derivative relationship exists between the machine performance, degradation, and the underlying stressor. The derivative relationship may be used to make diagnostic and prognostic calculations concerning the performance and projected life of the machine. These calculations may be performed in real time to allow the machine operator to quickly adjust the operational parameters of the machinery in order to help minimize or eliminate the effects of the degradation mechanism, thereby prolonging the life of the machine. Various systems implementing the methods are also disclosed.

Abstract: Ice accretion on a probe is detected by determining the change of frequency of a vibrating type ice detector or sensor as ice starts to build up. The rate of change of frequency is determined and is combined with parameters including air velocity and air temperature for providing a signal that indicates liquid water content in the airflow as well as ice accretion on the ice detector.

Abstract: A system for monitoring a plumbing system having a plurality of fixtures includes a sensor vibrationally coupled to the plumbing system and a processor. The sensor detects a vibration produced by the plumbing system, and generates a signal representative of the vibration. The processor receives the signal, compares the signal to a signal database that associates each of a plurality of stored signals with operation of one or more of the fixtures, and determines that the associated fixture or group of fixtures has been operated based on the comparison. The processor also stores a record of the operation of the associated fixture or group of fixtures.

Abstract: Flow meter electronics are described for providing a flow rate of a material flowing through a flow meter sensor of a Coriolis flow meter. The flow meter electronics comprise a processing system and a single output port. The processing system receives pick-off signals from the flow meter sensor and processes the pick-off signals to determine the flow rate. The processing system receives an instruction for a frequency output signal or a digital communication protocol signal. If the instruction is for a frequency output signal, then the processing system processes the flow rate to generate a frequency output signal and transmits the frequency output signal over the single output port. If the instruction is for a digital communication protocol signal, then the processing system processes the flow rate to generate a digital communication protocol signal and transmits the digital communication protocol signal over the single output port.

Abstract: A device for performing the manipulation of particles suspended in a fluid is disclosed. The device comprises a duct for the flow of a fluid in which particles are suspended, an acoustic transducer, and a reflector for establishing an acoustic standing wave field across the width of the duct. It has been unexpectedly found that optimum performance of the device occurs when the spacing between the transducer and a reflector is 300 microns or less. The device seeks to overcome prior engineering difficulties that prevented one from observing the individual particle bands or separating the individual particle bands from the duct.

Abstract: An apparatus and method for detecting a leak in a pipe, the apparatus comprising a sensor (11) located at a pipe (7), configured to detect a signal from the pipe, converter means to convert the signal detected by the sensor into a digital signal, and transform means to transform the digital signal into a different orthogonal space. The apparatus also comprises a transmitter (15) for transmitting the transformed digital signal back to a remote processor.

Abstract: Flow meter electronics are described for providing a flow rate of a material flowing through a flow meter sensor of a Coriolis flow meter. The flow meter electronics comprise a processing system and a single output port. The processing system receives pick-off signals from the flow meter sensor and processes the pick-off signals to determine the flow rate. The processing system receives an instruction for a frequency output signal or a digital communication protocol signal. If the instruction is for a frequency output signal, then the processing system processes the flow rate to generate a frequency output signal and transmits the frequency output signal over the single output port. If the instruction is for a digital communication protocol signal, then the processing system processes the flow rate to generate a digital communication protocol signal and transmits the digital communication protocol signal over the single output port.

Abstract: A flow rate measuring apparatus includes: flow rate detection section 2 and 3 provided in a fluid flow path 1; a measuring section 10 for measuring an output from the flow rate detection sections 2 and 3; a cycle setting section 9 for setting a measurement cycle of the flow rate detection sections 2 and 3; a resolution setting section 7 for setting a measurement resolution of the measuring section 10; a flow rate calculation section 11 for calculating a flow rate based on an output from the measuring section 10; and a measurement control section 12 for controlling each of the sections.

Abstract: The invention provides a method for testing oscillators in which cracks and chips on oscillator chips that may possibly have an effect on the oscillation characteristics can be detected efficiently, without using an optical examination device and an image processing device, which require troublesome adjustment and higher cost. When testing the oscillation characteristics of oscillator chips, the method comprises a network analyzer, an upper electrode, a lower electrode, an oscillator chip, a bush, and a personal computer. The personal computer is connected to the network analyzer using a GP-IB interface cable, and is capable of storing, displaying, and comparing all measurement results of the network analyzer. The upper electrode can be shifted vertically by a vertical mechanism.

Abstract: A method for inspecting pipe, the method, in at least certain aspects, including detecting an inspection parameter in at least a first part of a pipe, the pipe having a length, a hollow body, an outer surface, and a generally circular pipe wall with an inner diameter and an outer diameter, locating at a first location the first part of the pipe with respect to the length of the pipe and with respect to the outer diameter of the pipe; and such a method for inspecting pipe which, in at least certain aspects, includes detecting at least a first part of a first imperfection of the pipe.

Abstract: The testing performs a vibration excitation testing of a part of the structure, performs a numerical calculus of vibration response of the other parts of the structure, and calculates the vibration response of a whole of the structure by combining these two methods. Testing includes calculating a position of a point of exciting force on the basis of vibration exciting, and calculating a reaction force on the basis of a load detected and the position of the point of exciting force. Then, a displacement of a numerical model is computed by using the reaction force calculated and a known external force, and calculating a vibration exciting machine displacement command value on the basis of the displacement. A drive drives the vibration exciting on the basis of an output thereof. Vibration excitation is performed in the translational direction as well as the rotational direction.

Abstract: The invention provides a method and an apparatus for measuring the size, concentration and size distribution of particles in a fluid by determining the characteristics of an acoustic speckle signal of the particles and relating these characteristics to the size and concentration characteristics of the particles. The method and the apparatus are especially useful for the measurement of the size distribution of small particles in optically opaque liquids.

Abstract: Movement of a structure, such a conduit of a Coriolis mass flowmeter, is estimated. A plurality of motion signals representing motion of the structure are mode selective filtered to generate a plurality of mode selective filtered motion signals such that the mode selective filtered motion signals preferentially represent motion associated with a vibrational mode of the structure. A plurality of phase estimates is generated from the plurality of mode selective filtered motion signals. The plurality of phase estimates may be generated using a phase reference derived from a mode selective filtered motion signal of the plurality of mode selective filtered motion signals. According to some embodiments, a frequency of a mode selective filtered motion signal is estimated, and quadrature first and second reference signals are generated based on the estimated frequency. The plurality of phase estimates is generated from the mode selective filtered motion signals and the reference signals.

Abstract: This invention unifies a set of statistical signal processing, neuromorphic systems, and microelectronic implementation techniques for blind separation and recovery of mixed signals. A set of architectures, frameworks, algorithms, and devices for separating, discriminating, and recovering original signal sources by processing a set of received mixtures and functions of said signals are described. The adaptation inherent in the referenced architectures, frameworks, algorithms, and devices is based on processing of the received, measured, recorded or otherwise stored signals or functions thereof. There are multiple criteria that can be used alone or in conjunction with other criteria for achieving the separation and recovery of the original signal content from the signal mixtures. The composition adopts both discrete-time and continuous-time formulations with a view towards implementations in the digital as well as the analog domains of microelectronic circuits.

Abstract: Ice accretion on a probe is detected by determining the change of frequency of a vibrating type ice detector or sensor as ice starts to build up. The rate of change of frequency is determined and is combined with parameters including air velocity and air temperature for providing a signal that indicates liquid water content in the airflow as well as ice accretion on the ice detector.

Abstract: A method for inspecting pipe, the method, in at least certain aspects, including detecting an inspection parameter in at least a first part of a pipe, the pipe having a length, a hollow body, an outer surface, and a generally circular pipe wall with an inner diameter and an outer diameter, locating at a first location the first part of the pipe with respect to the length of the pipe and with respect to the outer diameter of the pipe; and such a method for inspecting pipe which, in at least certain aspects, includes detecting at least a first part of a first imperfection of the pipe.

Abstract: Monitoring modules of a monitoring and protection system are disposed in groups proximate to points of interest in a machine system where dynamic operating conditions are monitored. A master module, which may be a similar monitoring module or a different device such as a gateway, stores user configuration parameters that are also stored in the monitoring modules. In the event of loss of service or replacement of a module, once the same or a different module is detected by the master, the configuration parameters are restored to the monitoring module to permit continuity of operation. The parameters may include multiple settings such as alarm levels, units of measure, processing parameters, response settings, and so forth.

Abstract: Drive techniques for a digital flowmeter are described. The drive techniques account for delays caused during digital signal processing of sensor signals that correspond to a motion of a flowtube, as well as drive signals that impart motion to the flowtube. Such delays may be caused by a variety of factors, including delays associated with analog/digital conversion of the signals and/or filtering of the signals. The techniques include open-loop techniques and closed-loop techniques, which can be used separately or together during the start-up and operation of the digital flowmeter.

Abstract: An apparatus for noninvasively monitoring the flow and/or the composition of a flowing liquid using ultrasound is described. The position of the resonance peaks for a fluid excited by a swept-frequency ultrasonic signal have been found to change frequency both in response to a change in composition and in response to a change in the flow velocity thereof. Additionally, the distance between successive resonance peaks does not change as a function of flow, but rather in response to a change in composition. Thus, a measurement of both parameters (resonance position and resonance spacing), once calibrated, permits the simultaneous determination of flow rate and composition using the apparatus and method of the present invention.

Abstract: Sound detection techniques and sound discrimination techniques are used to analyze the real time sounds generated during the operation of cleaning heads operating within a vessel to determine if the cleaning heads are operating properly. During a typical cleaning operation pressurized cleaning solution is dispensed through a rotating nozzle assembly inside the vessel. As the nozzles rotate the spray moves about the interior of the vessel creating a unique sound pattern. By placing one or more pickups on the exterior of the vessel the sound is captured and fed to an analyzing device for analysis. Key properties such as, but not limited to, sound pressure levels, amplitude variations, spectral content, and rotational information are extracted and analyzed against the reference parameters.

Abstract: The invention provides devices and methods for acoustically assessing the contents of a plurality of reservoirs that are typically provided as an array. An acoustic radiation generator is employed for generating acoustic radiation having an image field of a size sufficient to interrogate a plurality of selected reservoirs at one time. The generator is placed in acoustic coupling relationship via a fluid acoustic coupling medium to the selected reservoirs, and acoustic radiation generated by the generator is transmitted through the coupling medium, an exterior surface of the selected reservoirs, and the selected reservoirs. A characteristic of the transmitted acoustic radiation is analyzed so as to assess the contents of each of the selected reservoirs. Fluid may be ejected from the selected reservoirs according to the assessment. Optionally, a means is provided for removing fluid acoustic coupling medium from the exterior surface after acoustic assessment.

Abstract: The invention relates to acoustic detection of leaks in a pipeline using locally-intelligent, data-adaptive monitors deployed for a period of time. Monitors are initialized by a base station. Following deployment, monitors receive vibration signals at programmed times, process the vibration signals to detect and characterize abnormal vibrations, and save the processed data in the monitor. Monitors may communicate digitally with a base station, sending processed data and receiving instructions. Alternatively, monitors may be removed from the pipeline and placed in a docking station prior to initialization and subsequent re-deployment on a pipeline. A procedural step of re-synchronization corrects for any mis-alignments in time that may occur among received vibration signals from different monitors. Received vibration signals from two or more monitors may then be analyzed using a correlative method to localize the position of any leaks present in the pipeline.

Abstract: Ice accretion on a probe is detected by determining the change of frequency of a vibrating type ice detector or sensor as ice starts to build up. The rate of change of frequency is determined and is combined with parameters including air velocity and air temperature for providing a signal that indicates liquid water content in the airflow as well as ice accretion on the ice detector.

Abstract: A process for analyzing a signal which composed of a sequence of discrete amplitude values to which portions with different phase angle contribute. Here, a reshaped signal is formed in which the sequence of amplitude values is changed such that the amplitude values, or instead of them approximation values which have been brought near the amplitude values, follow one another in ascending or descending sequences according to their size.

Abstract: An apparatus and method for determining a density compensated flow rate of a material flowing through a vibrating conduit. Signals are received from sensors affixed to the vibrating conduit. An uncompensated flow rate of said material is then calculated from the signals. A density compensation factor is then determined from the uncompensated flow rate and non-linear information relating density to errors in flow rate. The density compensated flow rate is then determined by applying the density compensation factor to the uncompensated flow rate.

Abstract: Improved approaches to assist those having hearing loss are disclosed. One approach pertains to providing on-line hearing loss testing. The on-line hearing loss testing can be self-performed without any specialized equipment. Another approach pertains to on-line sound customization. The sound customization can simulate hearing compensation on-line. As an example, the hearing compensation can be used to simulate hearing aid processing. Still another approach pertains to a recommendation and/or referral procedure.

Abstract: A digital signal processor for determining a property of a material flowing through a conduit. The digital signal processor of this invention receives signals from two pick-off sensor mounted at two different points along a flow tube at a first sample rate. The signals are converted to digital signals. The digital signals are decimated from a first sample rate to a desired sample rate. The frequency of the received signals is then determined from the digital signals at the desired sample rate.

Abstract: A system for initializing parameters in a drive circuit. This invention applies initial drive signals to a drive circuit which causes said flow tube to vibrate. The configuration of the flow tube is then determined from pick-off signals received from pick-off sensors associated with the flow tube. Parameters for generation of said drive signals are then set based upon the configuration of said flow tube.

Abstract: A fault tolerant liquid measurement system includes a plurality of sensors for measuring parameters of a liquid in a container; each sensor generating a measurement signal representative of the liquid parameter measured thereby. The sensors are grouped into a number of sets, each set including some sensors of another set. The measurement signals of each set of sensors are processed in a processor to determine for each set of sensors a first estimate signal representative of a likelihood of measurement signal validity for the measurement signals of the corresponding set, and a second estimate signal representative of liquid quantity in the container based on the measurement signals of the corresponding set. The processor further determines a third estimate signal of liquid quantity in the container based on a function of the first and second estimate signals.