Abstract: The invention relates to an inductive proximity sensor with a sensor element which includes a resonant circuit which provides an output signal which depends on the damping by an electrically conductive object. In accordance with the invention, the inductive proximity sensor has a ?? modulator for the evaluation of an output signal of the resonant circuit. The invention furthermore relates to a method for the determination of the presence and/or of the spacing of a metallic object with the help of an inductive proximity sensor.

Abstract: A method and related system calibrating downhole tools for drift. Some of the illustrative embodiments are a logging tool comprising a tool body, a transmitter antenna associated with the tool body, a transmitter electronics coupled to the transmitter antenna, a first receiver antenna associated with the tool body, a first receiver electronics coupled to the first receiver antenna, and a signal generator separate from the first transmitter electronics, the signal generator coupled to the first receiver electronics, and the first signal generator provides a calibration signal to the first receiver electronics.

Abstract: A method of inspecting a test part is provided. The method includes positioning an eddy current probe on a surface of the test part and scanning the test part using the eddy current probe to generate a first signal corresponding to a no lift-off condition of the test part. The method further includes positioning the eddy current probe at a pre-determined distance from the surface of the test part and scanning the test part using the eddy current probe positioned at the pre-determined distance from the test part to generate a second signal corresponding to a lift-off condition of the test part. The method also includes processing the first and second signals to estimate an electrical conductivity of the test part.

Abstract: Methods are provided for calibrating a tachometer or generator device to reduce residual errors associated with the tachometer-generator device. A shim structure is positioned within the air gap of the tachometer-generator device. A physical characteristic or location of placement of the shim structure is selected to reduce variation in an output voltage of the tachometer-generator device.

Abstract: A device rotates at least one static magnetic field about an axis, producing a rotating magnetic dipole field, and is movable in relation to the surface of the ground. The field is periodically sensed using a receiver to produce a receiver output responsive to the field. A positional relationship between the receiver and the device is monitored using the output. In one aspect, changing the positional relationship, by moving the device nearer to a boring tool which supports the receiver, causes an increase in accuracy of depth determination. In another aspect, determination of an actual overhead position of the boring tool, and its application, are described. Use of a plurality of measurements over at least one-half revolution of each magnet is disclosed. Establishing a surface radial direction toward a boring tool and resolution of multi-valued parameters is described. Calibration techniques, as well as a three transmitter configuration are also described.

Abstract: One or more sensors in a portable electronic device have individual status parameter in response to different using configurations. When the portable electronic device operates in a first using configuration, an electronic compass in the portable electronic device loads a corresponding first default setting, according to the status parameter of the sensors operated in the first using configuration, and detects the geomagnetic field for outputting azimuth data. When the portable electronic device changes its configuration from the first using configuration to a second using configuration, the electronic compass stops detecting the geomagnetic field and loads a corresponding second default setting, according to the status parameter of the sensors operated in the second using configuration, and detects the geomagnetic field for outputting azimuth data.

Abstract: Systems, methods, and other embodiments associated with mitigating off-resonance angle in steady-state coherent magnetic resonance imaging (MRI) are described. One example method includes accessing a B0 map and a coil sensitivity profile associated with an MRI apparatus configured to produce a steady-state coherent MRI sequence to image an object. The MRI apparatus is configured with a multi-channel transmission array having individually controllable transmission channels. The method includes computing transmission control parameters for individual transmission channels as a function of the B0 map and the coil sensitivity profile. The transmission control parameters are configured to facilitate controlling the transmission array to create a spatially varying phase profile using a single dimensional radio frequency (RF) pulse.

Abstract: Using eddy currents for automatic inspection of a rectilinear hole formed in a metal part. An eddy-current probe is carried by a drive system associated with a positioning baseplate that carries a calibration part including a hole similar to the hole for inspection and in alignment with an orifice thereof.

Abstract: A marine electromagnetic sensor system includes a sensor cable having at least one electromagnetic sensor thereon. A first calibration electrode is disposed on the cable on one side of the sensor. A second calibration electrode is disposed on the cable on an opposite side of the sensor. A calibration power supply is coupled to the first and second calibration electrodes. A measuring circuit is coupled to the sensor. A method for calibrating marine electromagnetic survey electrodes includes imparting electric current between calibration electrodes disposed at spaced apart locations on a cable deployed in the water. Voltages impressed across a pair of electrodes disposed on the cable between the calibration electrodes are detected in response to the current. A change in sensitivity of the at least one pair of electrodes is determined using the detected voltages.

Abstract: Double modulation of a magnetoresistive sensor entails modulating both an excitation (e.g., voltage or current) applied to the sensor and a tickling magnetic field applied to the sensor. The excitation and magnetic field are modulated at different frequencies fc and ff, respectively. As a result of the double modulation, the sensor output spectrum includes a carrier tone (CT) at frequency fc and side tones (STs) at frequencies fc±ff. A baseline relation between CT amplitude and ST amplitude is determined (e.g., by measuring CT and ST amplitude while drift occurs in the absence of a sample). During sensor operation, raw ST measurements are corrected using corresponding raw CT measurements to provide corrected ST measurements as the sensor output.

Abstract: A magnetic field sensor includes built in self-test circuits that allow a self-test of most of, or all of, the circuitry of the magnetic field sensor, including self-test of a magnetic field sensing element used within the magnetic field sensor, while the magnetic field sensor is functioning in normal operation.

Abstract: An antenna orientation sensor, having a base, a pivoting support coupled to the base. An actuator operable to move the pivoting support through a calibration movement with respect to the base. A magnetic sensor on the pivoting support and a position sensor operable to sense the position of the pivoting support within the calibration movement.

Abstract: A system including magnetic sensing elements and a circuit. The magnetic sensing elements are configured to sense a magnetic field that is generated via a current and to provide signals that correspond to the magnetic field. The circuit is configured to determine calibration values based on the signals and measure the current based on the signals.

Abstract: The invention concerns a system for measuring the alignment error of two axles provided with a first and a second coupling part by means of a biaxial orthogonal magnetic sensor system comprising a sensor and a magnet, wherein said sensor is designed to be placed on the first coupling part with its one direction of sensing oriented in one direction of magnetization of said magnet, which magnet is designed to be placed on the other coupling part and means for reading off an angle error and offset error independently of each other during the rotation of the axles on-line. The system moreover includes a reference sensor for determining said angle error and offset error orientation relative to a known direction.

Abstract: Provided is a method of using a rotational movement amount of a mobile device including obtaining images at two different points on a path along which the mobile device moves, searching for matching points with respect to the obtained images and obtaining an image coordinate value of each of the matching points, sensing linear movement of the mobile device and obtaining a linear movement amount using a result of sensing, and obtaining the rotational movement amount using the image coordinate values and the linear movement amount.

Abstract: A magnetic field sensor comprises a reference magnetic field generator (8), a magnetic field sensing cell (6) including Hall effect sensing elements (12), and a signal processing circuit (4) connected to the output (11) of the magnetic field sensing cell and comprising one or more feedback lines (27, 28) for correcting error fluctuations in the transfer characteristic of the magnetic field sensor. The reference magnetic field generator is adapted to generate a frequency modulated reference magnetic field. The signal processing circuit further includes a modulator connected to the magnetic field sensing cell, adapted to modulate the output signal thereof at a frequency different from the modulation frequency of the reference magnetic field generator.

Abstract: Device for calibration of a field transmitter comprising a shaped body on which there are disposed first means for sensing magnetic fields the activation of which allows calibration of a first measurement parameter of the transmitter, second means for sensing magnetic fields the activation of which allows calibration of a second measurement parameter of the transmitter, magnetic actuation means suitable to activate said first and second means for sensing magnetic fields. Said shaped body is configured so that it can be removably connected to the transmitter on the external surface of the enclosure thereof.

Abstract: A metal detector (40) used for identifying contaminants in products (23) introduced into the metal detector by a conveyor. The detector (40) includes coils (1), a search head (2) and an analog to digital converter (3) that generates a reactive signal (13) in response to the presence of a contaminant in the region of the coils. A calculation processor (32 ) receives the reactive signal (13) along with the value of the conveyor speed (9) to determine a calibration ratio R that is unique to each individual metal detector (40). The optimum frequency F for metal detector operation is equal to the conveyor speed (9) divided by the ratio R. The ratio R simplifies the selection of filter parameters (4, 8) for a speed filter (30) which correlates the conveyor speed (9) with the frequency F so as to deliver an optimized signal to the detection algorithm (10) used to determine the presence of a contaminant based on the signal (13) derived from the coils (1).

Abstract: Systems and methods according to exemplary embodiments address, among other features, the area of calibrating a sensor using a constant vector field. In one exemplary embodiment, a method for calibrating a sensor includes the steps of placing the sensor in a cube, rotating the cube between a plurality of different orientations, collecting at least one reading from the sensor from each of the plurality of different orientations and calibrating the sensor using the collected readings.

Abstract: An apparatus and method for identifying the position of a magnetic shaft are provided. N field sensors are adjacently positioned at fixed locations relative to the shaft's periodic field, corresponding to 180/N relative phase shifts. A table provides N>2 predetermined signal models and a pre-identified position associated with each. An interpolator compares a representation of the N measured sensor signals to at least two predetermined models to generate a correction signal that provides another pre-identified position. The correction signal depends on N sensors for every position of the shaft. The correction signal is used to incrementally choose said another pre-identified position from the table as an approximate position of the shaft in an iterative process to find the minimum correction signal and identify the position.

Abstract: Methods and apparatus are described for absolute electrical property measurement of materials. This is accomplished with magnetic and electric field based sensors and sensor array geometries that can be modeled accurately and with impedance instrumentation that permits accurate measurements of the in-phase and quadrature phase signal components. A dithering calibration method is also described which allows the measurement to account for background material noise variations. Methods are also described for accounting for noise factors in sensor design and selection of the optimal operating conditions which can minimize the error bounds for material property estimates. Example application of these methods to automated engine disk slot inspection and assessment of the mechanical condition of dielectric materials are presented.

Abstract: Apparatus for assessing field distortion includes a probe and a processor. The probe includes a mechanical fixture for placement at a location to be tested, and one or more field generators, which are attached to the mechanical fixture and are arranged to generate respective magnetic fields. The probe further includes one or more field sensors, which are attached to the mechanical fixture at known positions with respect to the one or more field sensors and are arranged to sense the magnetic fields generated by the one or more field generators and to output signals responsively to the sensed magnetic fields. The processor is arranged to process the signals so as to assess a distortion of the magnetic fields sensed by the field sensors at the tested location.

Abstract: An increment sensor assembly inquires an microcontroller as to the last known increment when a vehicle is started. The last known increment data is used to rotate the sensor backward to reach a lower mechanical stop position or forward to reach an upper mechanical stop position. A timer tracks the sensor to ensure that one of the known stop positions is reached within a predetermined time period or performs a system check to determine what error has occurred. Once the sensor reaches one of the known stop positions an increment counter is reset and the sensor assembly begins normal operation.

Abstract: An angle measurement system including a magnet coupled to a rotating member and adapted to provide a magnetic field which rotates with the rotating member about a rotational axis of the rotating member, and an integrated circuit angle sensor disposed within the magnetic field at a radially off-center position from the rotational axis. The integrated circuit angle sensor includes first and second bridges of magneto resistive elements configured to respectively provide first and second signals representative of substantially orthogonal first and second directional components of the magnetic field and together representative of an angular position of the rotating member, and a set of adjustment parameters for adjusting attributes of the first and second signals having values selected to minimize errors in the first and second signals.

Abstract: Systems and methods for performing a self-test on a sensing device are described in the present disclosure. One implementation, among others, includes a method of performing a self test. In this implementation, the method includes supplying a periodic magnetic field upon a sensing element that is configured to sense a parameter of an object. The method further includes receiving an output from the sensing element indicating the operability of the sensing element. It should be noted that the output is received independently of the parameter of the object.

Abstract: An angular position measurement system including a continuous angular position sensor configured to provide a first signal representative of a continuous angular position of a rotating shaft, an incremental angular position sensor configured to provide a second signal representative of incremental angular positions of the rotating shaft, and a controller configured to calibrate the first signal based on the second signal to provide a third signal representative of a calibrated continuous angular position of the rotating shaft.

Abstract: An electromagnetic logging tool is disclosed that includes a support; and at least one four-coil array disposed on the support, wherein the at least one four-coil array comprises: a transmitter, a bucking coil, a receiver, and a trim coil. A method for balancing an induction array is disclosed that includes applying an alternating current to a transmitter of the induction array that comprises the transmitter, a bucking coil and a receiver; measuring a mutual coupling between the transmitter and the receiver; and adding an extra bucking coil, if the mutual coupling exceeds a selected criterion.

Abstract: A magnetic field verifier apparatus includes a magnetic field detection element configured to produce a voltage signal in response to an applied magnetic field wherein the voltage signal corresponds to the strength of the applied magnetic field. A current source coupled to the magnetic field detection element provides a stimulating current for the magnetic field detection element that builds in a ramp-like progression. A microcontroller is in communication with the voltage signal wherein the microcontroller is configured to detect and control the ramping time of the magnetic field detection element and to sense after the ramping time the voltage signal from the magnetic field detection element. The magnetic field verifier apparatus is configurable to sense particular field strengths at various frequencies and store the readings to provide the user with a reliable verification that a particular magnetic field strength has been produced in a particular environment.

Abstract: Reference standards or articles having prescribed levels of damage are fabricated by monitoring an electrical property of the article material, mechanically loading the article, and removing the load when a change in electrical properties indicates a prescribed level of damage. The electrical property is measured with an electromagnetic sensor, such as a flexible eddy current sensor, attached to a material surface, which may be between layers of the article material. The damage may be in the form of a fatigue crack or a change in the mechanical stress underneath the sensor. The shape of the article material may be adjusted to concentrate the stress so that the damage initiates under the sensor. Examples adjustments to the article shape include the use of dogbone geometries with thin center sections, reinforcement ribs on the edges of the article, and radius cut-outs in the vicinity of the thin section.

Abstract: A method of surveying a pipeline is provided. The pipeline comprises a tubular member with a protective wrapping. The method comprises the steps of applying signal to the pipeline from a first location, which first location is remote from the pipeline, and measuring the signal from a second and third locations. The second and third locations are remote from the pipeline and the second location is spaced from the third location along the pipeline. The signals received at the second and third location are used to provide an indication of deterioration of the signal along the tubular member and/or wrapping between the second and third locations.

Abstract: An integrated circuit including an amplifier and a first circuit. The amplifier is configured to receive a sensed signal and provide an amplified signal. The first circuit is configured to track a first signal that is based on the amplified signal. The first circuit includes a first comparator, tracking logic and a first digital to analog converter. The first comparator is configured to respond to a second signal that is based on the first signal and provide a comparator output signal. The tracking logic is configured to receive the comparator output signal and update a digital output. The first digital to analog converter is configured to receive the digital output and provide a tracking signal that is summed with the first signal to provide the second signal.

Abstract: A calibration apparatus for a hand-held locating device (7) has at least one first coil configuration (1a) having a first measuring range (2?) and a second coil configuration (1a?) having a second measuring range (2a?), in which measuring ranges (2a, 2a?) homogeneous alternating magnetic fields can be generated in a specifiable ratio with respect to the strength of the magnetic fields. The coil configurations (1a, 1a?) are arranged a specifiable distance apart so that the magnetic fields can be detected simultaneously by means of at least two aerials of the locating device (7) which are arranged at a fixed distance. The specifiable ratios define true distance parameters.

Abstract: A self-calibrating magnetic field monitor is disclosed. In one embodiment, a magnetic field sensor repeatedly generates an electronic signal related to the magnetic field. In addition, a calibration module generates a relative baseline signal based on an average value of the electronic signals for a given time period. A comparator compares the electronic signal with the relative baseline signal and generating an output signal if a difference in the comparing is greater than or equal to a threshold.

Abstract: The present invention provides a magnetic sensor device comprising a plurality of magnetic sensor elements having a sensitive direction. At least one of the magnetic sensor elements (43) is provided with a flux-guide (44) for concentrating onto the sensor element in its sensitive direction a magnetic field applied to the magnetic sensor device. The applied magnetic field is thus bent into the sensitive direction of the magnetic sensor element by the flux-guide. In that way, the field strength and/or orientation of the applied magnetic field can be measured in the absence of magnetic particles. This may be used for, for example, calibration of magnetic sensor devices.

Abstract: Method and apparatus improve sensing accuracy and reduce bias shift in anisotropic magneto-resistive sensors using paired integrators and sampling switches for processing outputs of the sensor on applied set and reset signals with high immunity to temperature variations.

Abstract: A transmitting circuit 10 converts transmission data to a multilevel analog signal suitable for transmission. The multilevel analog signal is output to a cable 21 via an amplifier and a hybrid circuit 12. In the transmitting circuit 10, a waveform which compensates waveform deterioration at the cable 21 is generated. A reception signal from the cable 21 is input to a mixer 14 via the hybrid circuit 12 and an amplifier 13. The mixer 14 mixes the reception signal and a cancel signal output from a cancel signal generation circuit 17 so as to remove undesired signals. In a receiving circuit 15, the signal output from the mixer 14 is sampled by use of a plurality of sample-hold circuits, and subjected to analog sum-of-product computation which is performed by a matrix circuit for distortion compensation. Subsequently, the sampled signals are converted to digital signals.

Abstract: Magnetic field sensors have a magnetic field sensing element and also a feedback circuit to provide a gain-adjustment signal to affect a sensitivity associated with the magnetic field sensing element. In some arrangements, the feedback circuit can include piezoresistors to sense a strain of a substrate over which the magnetic field sensor is disposed. With these arrangements, the feedback circuit can generate the gain-adjustment signal in accordance with the sensed strain. In other arrangements, the feedback circuit can generate pulsed magnetic fields proximate to the magnetic field sensing element in order to directly measure the sensitivity of the magnetic field sensing element. With these arrangements, the feedback circuit can generate the gain-adjustment signal in accordance with the sensed sensitivity.

Abstract: Bi-axial tilt monitoring apparatus and method for bi-axial tilt monitoring of an article using a single-axis tilt monitoring device. A bi-axial tilt monitoring apparatus according to exemplary embodiments includes a single-axis tilt monitoring device and a support member supporting the single-axis tilt monitoring device and mountable to an article to be monitored. The support member has a supporting surface for supporting the single-axis tilt monitoring device at an acute angle relative to a substantially vertical surface of the article to be monitored when the tilt monitoring apparatus is mounted to the article to be monitored.

Abstract: A magnetic screening system uses directional gradiometers with high resolution and accuracy to measure magnetic field signatures of target objects (e.g., gun, knife, cell phone, keys) in a volume of interest. The measured signatures can be compared to signatures of known objects stored in a local database. Various mathematical processes may be used to identify or classify target object signatures. The magnetic screening system can operate in multiple modes, such as a tracking mode, measurement mode, calibration mode, and self-test mode. Calibration may be performed in substantially continous manner to allow calibration parameters to be adjusted during system operation (e.g., tracking mode) to compensate for changes in conditions that may impact calibration parameters. Through use of unique processes and designs, the magnetic screening system can achieve a high rate of processing persons for target objects.

Abstract: The invention relates to a magnetic sensor device comprising an excitation wire for the generation of an alternating magnetic excitation field (Bi) and a GMR sensor (12) for sensing reaction fields (B2) generated by magnetized particles (2) in reaction to the excitation fields. Moreover, it comprises a compensator (15) for the generation of a magnetic compensation field (B3) that adaptively cancels predetermined spectral components of all magnetic fields (B2, B3) which lie in the sensitive direction of the magnetic sensor element (12). Measurements of the GMR sensor (12) are thus made robust against gain variations of the sensor.

Abstract: A system for mapping a surface defect in an electrically-conducting material by measuring a change in the resonance of the material includes a flexible printed circuit board and a two dimensional array of transducers printed on the flexible circuit board, wherein each element of the array includes two transducer coils in a paired arrangement. A receive circuit connected to the coils is tuned to a resonant frequency, and the transducer coils operate in a send/receive mode. In another feature of the invention, there are means for converting a change in measured resonance to a visual display of the depth and width of the surface defect.

Abstract: A calibrating method for a portable electronic device having azimuth device such as an electronic compass is disclosed. The calibrating method can be achieved by checking at least one sensor in the portable device incorporating the electronic compass configured in the portable device, so as to effectively detect and verify a temporary abnormal magnetic field caused by a stylus movement. When the electronic compass detects an abnormal magnetic field, the operation status of the sensor is checked for any change existence. If the operation status of the sensors changes, the abnormal magnetic field is verified as a temporary magnetic filed due to the movement of the stylus, in which case the electronic compass passes the calibration and goes on detecting the geomagnetic field according to its default setting value.

Abstract: In one embodiment, a sensor assembly for measuring an angular position of a rotatable structure includes an annular ring that is eccentrically rotatable about an axis, a first and second sensors, and an sensor transducing circuit for combining the respective output levels from the two sensors. The first and second sensors are rotatable relative to the annular ring and disposed a predetermined distance from the axis such that the first and second sensors have a first and second output level respectively that is proportional to the angular position of the annular ring. The sensor transducing circuit is operable to proportionally combine the first and second output levels into an output signal based upon a weighting factor, the weighting factor being proportional to angular position of at least one of the first and second sensors.

Abstract: A magnetic field sensor assembly has at least one magnetic field sensor integrated into a semiconductor chip and has at least one magnetic field source. The semiconductor chip and the at least one magnetic field source are arranged in an encapsulation material in a predetermined position relative to each other in such a way that a magnetic field generated by the magnetic field source is detectable with the aid of at least one magnetic field sensor. The magnetic field source is arranged in the semiconductor chip and/or in the plane of extension of the semiconductor chip laterally adjacent to said chip.

Abstract: A method for reducing motion induced voltage in marine electromagnetic measurements includes measuring an electromagnetic field parameter at least one position along a sensor cable towed through a body of water. Motion of the sensor cable is measured at least one position along the cable; Voltage induced in the cable is estimated from the motion measurements. The measured electromagnetic field parameter is corrected using the estimated voltages.

Abstract: A method of determining an orientation of a data acquisition system deployed on a seafloor includes measuring horizontal magnetic fields using detectors on the data acquisition system while the data acquisition rotates and descends to the seafloor or rises from the seafloor. Resting horizontal magnetic fields are measured after the data acquisition system is on the seafloor. A heading of the data acquisition system on the seafloor may be determined based on maximum and minimum horizontal magnetic fields measured during the descent and the resting horizontal magnetic fields.

Abstract: The invention relates to the calibration of the magnetic sensor device comprising magnetic excitation wires (11, 13) and a magnetic sensor element, for example a GMR sensor (12), for measuring reaction fields (B2) generated by magnetic particles (2) in reaction to an excitation field (B1) generated by the excitation wires. The magnetic sensor element (12) can be calibrated by saturating the magnetic particles (2) with a magnetic calibration field (B3). Thus the direct (crosstalk) action of the excitation field (B1) on the magnetic sensor element (12) can be determined without disturbing contributions of the magnetic particles (2).

Abstract: A method of inspecting a test part is provided. The method includes positioning an eddy current probe on a surface of the test part and scanning the test part using the eddy current probe to generate a first signal corresponding to a no lift-off condition of the test part. The method further includes positioning the eddy current probe at a pre-determined distance from the surface of the test part and scanning the test part using the eddy current probe positioned at the pre-determined distance from the test part to generate a second signal corresponding to a lift-off condition of the test part. The method also includes processing the first and second signals to estimate an electrical conductivity of the test part.

Abstract: In a process for testing the measurement accuracy of at least one magnetic field sensor, in particular during manufacturing, a semiconductor wafer that has at least two semiconductor chips is provided. A measurement coil is integrated into at least one first semiconductor chip, and a magnetic field-sensitive electric circuit is integrated into at least one second semiconductor chip that forms the magnetic field sensor. The first semiconductor chip, of which at least one is present, is positioned at an exciter coil that is supplied with current in order to generate a reference magnetic field. With the aid of the measurement coil a first measured value that is dependent on the magnetic flux density is acquired and the current in the exciter coil is adjusted depending on the first measured value. The second semiconductor chip, of which at least one is present, is positioned at the exciter coil.

Abstract: The invention relates to a magnetic sensor device comprising excitation wires (11, 13) for generating a magnetic field (B) in a sample chamber (1) and a magnetic sensor element (12), for example a GMR element, for sensing magnetic fields generated by magnetic particles (2) in the sample chamber. The device further comprises a reference field generator consisting of a linear conductor (14) and a planar conductor (15) between which the magnetic sensor element (12) is disposed. The magnetic reference field (Bref) generated by said conductors (14, 15) does not penetrate into the sample chamber (1) but reaches only the magnetic sensor element (12). Components of the sensor signal which are due to the magnetic reference field (Bref) can therefore be separated and used to calculate the sensor gain. This value can for example be used for an auto-calibration of the device during a measurement.