Abstract: A method for discovering an unexploded ordnance in a target area includes: acquiring first feedback signals respectively corresponding to detection regions, the first feedback signals being first induced electromotive force signals; judging whether there is any abnormal signal in the first feedback signals, if there is the abnormal signal, determining the detection region corresponding to the abnormal signal is an abnormal region; acquiring second feedback signals respectively corresponding to detection sites in the abnormal region, the second feedback signals being magnetic field gradient signals; acquiring third feedback signals respectively corresponding to the detection sites, the third feedback signals being second induced electromotive force signals; acquiring location information of the detection sites; obtaining a feature spatial distribution map of the abnormal region; and judging whether there is any unexploded ordnance in the abnormal region according to the feature spatial distribution map.

Abstract: The present invention relates to a sensor suite comprising at least one sensor. More particularly, the present invention relates to a sensor suite for measuring absolute and/or relative position, location and orientation of an object on or in which the sensor suite is employed. The present invention further relates to improved, novel sensor types for use in the sensor suite. More particularly, the present invention relates to an improved, novel magnetometer that is self-calibrating and scalable. Still more particularly, the present invention relates to such a magnetometer that is miniaturized. Further embodiments of the present invention relate to systems and methods for providing location and guidance, and more particularly for providing location and guidance in environments where global position systems (GPS) are unavailable or unreliable (GPS denied and/or degraded environments).

Abstract: An etching method includes: preparing a workpiece including a metal multilayer film having a magnetic tunnel junction and a mask formed by an inorganic material on the metal multilayer film; and etching the metal multilayer film by plasma of a mixed gas of ethylene gas and oxygen gas using the mask.

Abstract: A field-sensor device comprises a first field sensor with a first sensor response to a field. The first sensor response is measured in a first orientation to produce a first sensor signal, a second field sensor with a second sensor response to the field the second sensor response measured in a second orientation different from the first orientation to produce a second sensor signal, and a controller for controlling the first and second field sensors to produce respective first and second sensor signals. The controller comprises a control circuit that converts any combination of first and second sensor signals to equivalent first and second comparable sensor signals in a common orientation, calculates an error signal derived from differences between the first and second comparable sensor signals, and adjusts any combination of the first and second sensor responses to reduce the error signal.

Abstract: The present invention relates to a calibration method of magnetic sensors, for removing from the measurements the so-called “bias” and obtaining the actual measurement of the magnetic field. This method, in addition to measurements of such magnetic sensors, uses measurements of angular rotation sensors available in various types of commercial devices including smartphones. The present invention also relates to a corresponding system for determining the instantaneous real time orientation and/or position of a mobile device with respect to a magnetic field.

Abstract: System, methods, and other embodiments described herein relate to location intelligence. In one embodiment, a method of obtaining location intelligence includes receiving a plurality of datasets from a plurality of vehicles, the datasets being associated with a same geographical location and respectively including at least vehicle descriptive information that describes one or more aspects of the respective vehicles and feature data that indicates a status of at least one respective feature of the respective vehicles, combining the plurality of datasets to form a location tensor associated with the geographical location, extracting, from the location tensor, an embedding that indicates information contained in the location tensor, and storing the embedding in a database in association with the geographical location.

Abstract: An MRI system includes a gantry having a longitudinal axis (herein “z-axis”) and a magnet disposed about the gantry for generating a static magnetic field along the longitudinal axis. Additionally, the system comprises a first gradient magnet for generating a gradient magnetic field along the longitudinal axis; a second gradient magnet for generating a gradient magnetic field along a first transverse direction (herein “x-axis”) orthogonal the longitudinal axis; and a third gradient magnet for generating a gradient magnetic field along a second transverse direction (herein “y-axis”) orthogonal to the longitudinal axis and the first transverse direction. Magnetic sensors are positioned relative to the gantry to measure gradients of transverse components of magnetic field along one or more of the x, y and z axes. A controller receives measurement signals from the sensors and operates on those signals to determine gradients of the gradient magnetic field along the longitudinal axis.

Abstract: Disclosed is an electronic device for measuring Electroencephalogram (EEG) signal or electronic stimulation, including at least: electrode modules that measures the EEG signal from a subject's head or apply current to the head; a control module that controls each of the electrode modules or applying current thereto; an EEG signal processing module that processes the EEG signal; an electric stimulation module that provides the electrode modules with a current for electric stimulation. The control module is further configured to: control each electrode module for measuring the EEG signal from the subject's head by controlling a switching module such that the each electrode module is connected with the EEG signal processing module; and control the each electrode module for applying current to the subject's head by controlling the switching module such that the each electrode module is connected with the electric stimulation module.

Abstract: A method includes acquiring magnetic data from a magnetometer, processing the magnetic data to perform robust calibration, and generating optimum calibration parameters using a calibration status indicator. To that end, the method includes generating a calibration status indicator as a function of time elapsed since a last calibration and variation in total magnetic field in previously stored magnetic data, detecting anomalies, and extracting a sparse magnetic data set using comparison between the previously stored magnetic data and the magnetic data. Calibration parameters are generated for the magnetometer using a calibration method as a function of the magnetic data set. The calibration parameters are stored based on performing a validation and stability check on the calibration parameters, and weighted with the previously stored calibration parameters to produce weighted calibration parameters.

Abstract: A method for locating at least one movable magnetic object with respect to an array of at least N triaxial magnetometers comprises steps consisting in: subtracting a weighted average from each of the measurements to obtain modified measurement; loading the modified measurements and a location of the one or more movable magnetic objects at the current time as input into a filtering operation for locating the one or more movable magnetic objects; implementing the location filtering operation, this comprises steps consisting in: subtracting a weighted average from each of the estimated data; and delivering as output a location of the one or more movable magnetic objects at a subsequent time.

Abstract: A magnetoencephalogram (MEG) system is provided for use with a head. The MEG system includes a shell, and three three-axis gradiometers and a computing portion. Each three-axis gradiometer detects a magnetic field vector from a magnetic dipole in the head and generates a respective detected signal based on the respective magnetic field vector. Each three-axis gradiometer is disposed at a respective position of the shell. The computing portion determines a location of the magnetic dipole based on the first detected signal, the second detected signal and the third detected signal.

Abstract: A wire machining method includes: a wire electrode set as cutting wires provided in parallel with a distance between the cutting wires of which a predetermined regional part faces a workpiece; a machining power source that generates a pulse-shaped machining voltage; and plural feeder units that are electrically connected to the plural cutting wires respectively of the wire electrode and supply the machining voltage between the cutting wires and the workpiece respectively. The feeder units are arranged such that a direction of a current passed to at least a part of the cutting wires becomes a direction different from a direction of a current passed to other cutting wires.

Abstract: In a method for manufacturing the functional element, a protective film covering an underlayer, a patterned multilayer film, and a patterned cap layer are formed, and the underlayer is then processed without newly forming a resist. Thereby, an electrode can be formed in steps less than ever before. Since the protective film formed on the patterned multilayer film and the patterned cap layer is used as a mask, the problem of the misregistration can be prevented.

Abstract: A method to measure a magnetic field is provided. The method includes applying an alternating drive current to a drive strap overlaying a magnetoresistive sensor to shift an operating point of the magnetoresistive sensor to a low noise region. An alternating magnetic drive field is generated in the magnetoresistive sensor by the alternating drive current. When the magnetic field to be measured is superimposed on the alternating magnetic drive field in the magnetoresistive sensor, the method further comprises extracting a second harmonic component of an output of the magnetoresistive sensor. The magnetic field to be measured is proportional to a signed amplitude of the extracted second harmonic component.

Abstract: A gear position sensor employs a sliding electrical connection between arcuate conductors and flexible wiper arms held on opposite surfaces that rotate relative to each other with the movement of a gear selector shaft. The traces may have multiple segments joined by resistors to provide flexible change in resistance value and resistance range for different applications.

Abstract: A rotation angle detecting unit includes an IC package having a magnetism detecting element, a sealing body, and leads; and a covering member having a fixing part and a supporting part, which are integrally formed from resin. The element outputs a signal according to change of a magnetic field generated upon rotation of a magnetism generating device attached to a detection object. The sealing body covers the element. The leads are connected to the element, and project from the sealing body. The fixing part is fixed to a supporting body so that the covering member is attached to the supporting body. The supporting part supports the package such that the element can output the signal. The package is press-fitted into the supporting part after its formation, so that the package is supported by the supporting part with a predetermined pressure applied to part of an outer wall of the sealing body.

Abstract: A magnetic field measuring system is disclosed. The magnetic field measuring system includes a substrate, a conductive well formed in the substrate, the well having a first side with a first length, a first contact electrically coupled to the conductive well at a first location of the first side, a second contact electrically coupled to the conductive well at a second location of the first side, wherein the distance between the first location and the second location is less than the first length, a stimulus circuit coupled to the first contact and the second contact, and a sensor for identifying a property indicative of the length of a current path from the first location to the second location through the conductive well.

Abstract: A geomagnetic application device including a triaxial magnetic sensor, a measurement point acquiring mechanism, a calibration mechanism calibrating offset of the magnetic sensor, and an azimuth calculator. The calibration mechanism includes an offset calculation measurement point selector selecting at least six measurement points of the geomagnetic vectors from among a data set stored in the measurement point storage unit by the measurement point acquiring mechanism and storing the selected measurement points in an offset calculation measurement point storage unit. The offset calculation measurement point selector selects the measurement points from among the data set stored in the measurement point storage unit to include at least six points, component values of which are maximum or minimum in each of three orthogonal axes.

Abstract: A multi-dimensional sensor, a magnetometer or accelerometer, is calibrated based on the raw data provided by the sensor. Raw data is collected and may be used to generate ellipse or ellipsoid parameters, for a two-dimensional or three-dimensional sensor, respectively. An offset calibration factor is calculated based on the raw data, e.g., the determined ellipse or ellipsoid parameters. A sensitivity calibration factor is then calculated based on the offset calibration factor and the raw data. A non-orthogonality calibration factor can then be calculated based on the calculated offset and sensitivity calibration factors. Using the offset, sensitivity and non-orthogonality calibration factors, the raw data can be corrected to produce calibrated data.

Abstract: A rotation angle detection device includes: a detection portion that detects detection angle that univocally corresponds to rotation angle of a rotating body which is within a predetermined range, wherein the detection angle linearly increases from a minimum value to a maximum value as the rotation angle increases within a unit range, and the detection angle changes from the maximum value to the minimum value or from the minimum value to the maximum value at a boundary between unit ranges that are adjacent to each other; and a correction portion that corrects the detection angle so that the detection angle detected in the predetermined range has linear characteristics, if the boundary between the unit ranges is contained in the predetermined range.

Abstract: A magnetic anomaly surveillance system includes triaxial magnetometer (TM) sensors arranged at known locations in an array. A processor coupled to the TM sensors generates a scalar magnitude of a magnetic anomaly field measured at each of the TM sensors. The scalar magnitude is indicative of a spherical radius centered at the known location associated with a corresponding one of the TM sensors. The processor also generates a comparison between each scalar magnitude and a threshold value. The processor then determines at least one magnetic anomaly location in the coordinate system via a spherical trilateration process that uses each spherical radius and each scalar magnitude associated with selected ones of the TM sensors for which the threshold value is exceeded. One or more output devices coupled to the processor output data indicative of the one or more magnetic anomaly locations.

Abstract: A stabilized field sensor apparatus collects field data, in particular magnetic field data, with reduced motion noise. The apparatus includes a tear drop shaped housing, a tow frame in the housing, a plurality of vibration isolating dampers spaced around the frame, a base assembly mounted to the dampers, a support pedestal having a bottom end fixed to the base assembly and an upper free end, a single spherical air bearing connected to the upper free end of the pedestal, an instrument platform with a lower hollow funnel having an upper inside apex supported on the air bearing for a one point support, principal and secondary gyro stabilizers for maintaining pivotal and rotational stability, and at least one field sensor mounted to the instrument platform for collecting the field data while being stabilized against motion noise including vibration, pivoting and rotation from the base assembly, from the tow frame and from the housing.

Abstract: An electromagnetic tracking system comprising at least one electromagnetic transmitter assembly or at least one electromagnetic receiver assembly with two coils attachable to a trackable object to be tracked. The two coils including a first large coil and a second small coil, with the second small coil positioned asymmetrically with respect to the first large coil. The electromagnetic tracking system enables a medical professional to continually track the position and orientation of the object during a medical procedure.

Abstract: A system for and method of determining and compensating for the effect of a field influencing object on a field sensor, preferably a coil, that is within a navigational domain. The navigational domain contains navigational magnetic energy and disturbing magnetic energy, and the field influencing object produces the disturbing magnetic energy in response to the navigational magnetic energy. The correction system includes a first transmitter for projecting into the navigational domain field energy in a first waveform sufficient to induce a first signal value in the sensing coil. The system also includes a second transmitter for projecting into the navigational domain field energy in a second waveform sufficient to induce a second signal value in the sensing coil. The system further includes a signal processor for receiving the first signal value and for receiving the second signal value to determine the effect of the electrically conductive object on the field sensor.

Abstract: A semiconductor process and apparatus provide a high-performance magnetic field sensor from two differential sensor configurations (201, 211) which require only two distinct pinning axes (206, 216), where each differential sensor (e.g., 201) is formed from a Wheatstone bridge structure with four unshielded MTJ sensors (202-205), each of which includes a magnetic field pulse generator (e.g., 414) for selectively applying a field pulse to stabilize or restore the easy axis magnetization of the sense layers (e.g., 411) to eliminate micromagnetic domain switches during measurements of small magnetic fields.

Abstract: The device includes two supports and a primary conductive strip. The primary conductive strip includes a neutral surface, a first side, and a second side. The primary conductive strip is connected one of directly and indirectly on the first side to the two supports such that the primary conductive strip is constrained in two dimensions and movable in one dimension. The device also includes a primary distributed feedback fiber laser. The primary distributed feedback fiber laser includes a fiber axis. The primary distributed feedback fiber laser is connected to the primary conductive strip along one of the first side and the second side such that there is a positive distance between the neutral surface of the primary conductive strip and the fiber axis of the primary distributed feedback fiber laser.

Abstract: A magnetic anomaly sensing system and method uses at least four triaxial magnetometer (TM) sensors with each of the TM sensors having X,Y,Z magnetic sensing axes. The TM sensors are arranged in a three-dimensional array with respective ones of the X,Y,Z magnetic sensing axes being mutually parallel to one another. The three-dimensional array defines a geometry that forms at least one single-axis gradiometer along each of the X,Y,Z magnetic sensing axes. Information sensed by the TM sensors is to generate scalar magnitudes of a magnetic anomaly field measured at each of the TM sensors, comparisons of the scalar magnitudes to at least one threshold value, distance to a source of the magnetic anomaly field using the scalar magnitudes when the threshold value(s) is exceeded, and a magnetic dipole moment of the source using the distance.

Abstract: Substrates to be aligned include microcoils arranged at the level of their facing surfaces. In an alignment phase, power is supplied to at least the microcoils of the first substrate, whereas the inductance of the microcoils of the second substrate is measured. The microcoils are preferably flat microcoils in the form of a spiral or a serpentine.

Abstract: A system for and method of determining and compensating for the effect of a field influencing object on a field sensor, preferably a coil, that is within a navigational domain. The system includes a first and second transmitter to create signals. A signal processor is able to process the created signals. The method can include determining interference and/or a correct signal based on the two signals. Also, a shield can be provided to limit transmission of selected fields.

Abstract: A two-axis geomagnetic sensor is disclosed. The two-axis geomagnetic sensor includes a first geomagnetic sensor part including a first wafer and a first geomagnetic sensor on a surface of the first wafer; and a second geomagnetic sensor part including a second wafer and a second geomagnetic sensor on a surface of the second wafer. The first and second geomagnetic sensor parts are bonded to each other, in which the first and second geomagnetic sensors positioned in an orthogonal relation to each other. Accordingly, an occupancy area of the geomagnetic sensor can be reduced. Further, the geomagnetic sensor on each axe can have the same magnetic material properties, and alignment deviation cannot be generated.

Abstract: A method for processing biomagnetic fields generated by biocurrents resulting from activities of human brain or myocardia and its mapping apparatus are provided, which features biomagnetic measurement and its analysis, magnetic field mapping and its imaging and their waveform generation by a simple operation. Biomagnetic fields emitted from the patient are measured at a plurality of measurement positions, and a contour map of magnetic field obtained as a result of processing of these measured biomagnetic fields is imaged in the magnetic contour map display apparatus, which display apparatus comprises: the process function display area indicating process function items including measurement; and the analysis data display area which displays the waveform together with a designated measurement time, the waveform being generated during measurement at least based on the measured biomagnetic fields and during the designated measurement period of time.

Abstract: Methods and systems for monitoring rotating shaft shafts and couplings in an aircraft propulsion system is described. The measurement system/method provides for accurate and precise monitoring of a rotating shaft flexible coupling in a fixed wing aircraft vehicle propulsion system. The measuring system/method provides for a high reliability short take off vertical landing fixed wing aircraft in which the vertical propulsion dynamically rotating drive shaft system and couplings are monitored in real time. The vehicular shaft coupling misalignment measuring system utilizes multiple positional sensors to provide highly reliable and precise determination of the dynamic characteristics of the rotating sensor target components of the propulsion system drive shaft. The relative position of the sensors is rigidly fixed externally from the rotating targets with a structural frame.

Abstract: Method for determining the position or the orientation of an object using a magnetic field and corresponding device.

Abstract: A magnetic potential mapping device is provided by placing a planar polarized light source near an optically active fiber element traversing a magnetic field, so constructed that rotating planar polarized light is transmitted through the optical fiber and detected by a light detector at the fiber element's other end. The light detector measures an angle of rotation of rotating polarized light. Rotation of polarized light within the optical fiber traversing the field directly indicates magnetic potential at the point where the angle of rotation is measured, with respect to the magnetic potential at the point where the light entered the fiber element. Measuring the rotation of the polarized light passing through each fiber within the field allows mapping the magnetic potentials at any point in the magnetic field with respect to the point at which the light enters the optically active fiber. The present invention also contemplates a related method for automatically compensating a magnetic field source.

Abstract: A method for processing biomagnetic fields generated by biocurrents resulting from activities of human brain or myocardia and its mapping apparatus are provided, which features biomagnetic measurement and its analysis, magnetic field mapping and its imaging and their waveform generation by a simple operation. Biomagnetic fields emitted from the patient are measured at a plurality of measurement positions, and a contour map of magnetic field obtained as a result of processing of these measured biomagnetic fields is imaged in the magnetic contour map display apparatus, which display apparatus includes: the process function display area indicating process function items including measurement; and the analysis data display area which displays the waveform together with a designated measurement time, the waveform being generated during measurement at least based on the measured biomagnetic fields and during the designated measurement period of time.

Abstract: Inventive electrical-computational method and system for aligning a magnetic gradiometer, and for determining magnetic gradients using a magnetic gradiometer which is inventively aligned. For each correlation of a correction magnetometer's vector with a reference magnetometer's vector, three correction coefficients and an offset coefficient are evaluated, using a mathematical approximation technique (such as least-squares) upon voltage outputs for various relative orientations of magnetic fields in relation to a magnetic gradiometer. An inventive matrix formula is used for determining magnetic gradients. A correction magnetometer matrix (matrix of voltages generated by each correction vector of the correction magnetometer) is multiplied by a coefficient matrix (matrix of correction and offset coefficients).

Abstract: Inventive electrical-computational method and system for aligning a magnetic gradiometer, and for determining magnetic gradients using a magnetic gradiometer which is inventively aligned. For each correlation of a correction magnetometer's vector with a reference magnetometer's vector, three correction coefficients and an offset coefficient are evaluated, using a mathematical approximation technique (such as least-squares) upon voltage outputs for various relative orientations of magnetic fields in relation to a magnetic gradiometer. An inventive matrix formula is used for determining magnetic gradients. A correction magnetometer matrix (matrix of voltages generated by each correction vector of the correction magnetometer) is multiplied by a coefficient matrix (matrix of correction and offset coefficients).

Abstract: A vehicle compass system having a magnetic field sensor coupled to a processing circuit which samples the sensor data and implements a calibration routine that generates compensation signals to compensate the sensor for the effects of vehicular magnetism so that accurate heading information can be displayed on a display coupled to the processing circuit. If the signal levels detected are outside of a variable threshold, then the calibration routine is run. Also provided is a circuit for receiving vehicle position information in response to which the processing circuit adjusts the signals supplied to the display in order to account for magnetic variations between the true north and magnetic north.

Abstract: The present invention relates to a method and to a device (1) for correcting measurement errors of a magnetometer (2) mounted on a vehicle (3). According to the invention:a theoretical corrective model [A].Hm+a.Hm'+Hp=[M].H is defined, in which [A], a and H are elements to be determined, Hm is the measured field, Hm' the time derivative of Hm, H the effective field and [M] a transformation matrix;a vector error E=[M].H-([A].Hm+a.Hm'+Hp) is defined;the square of the error thus defined is determined; andthe coefficients of the model which minimize the sum of the squares of the errors for all the measurements taken are identified.

Abstract: A method and apparatus for determining the position and orientation of a remote object relative to a reference coordinate frame includes a source having a plurality of field-generating elements for generating electromagnetic fields, a drive for applying, to the generator element, signals that generate a plurality of electromagnetic fields that are distinguishable from one another, a remote sensor having a plurality of field-sensing elements for sensing the fields generated by the source, and a processor for processing the outputs of the sensing elements into remote object position and orientation relative to the source reference coordinate frame. The processor compensates the position and orientation values as a function of displacement of either the field-generating elements from a common center, or the field-sensing elements from a common center, or both.

Abstract: An electronic compass (10) having at least two sense windings (11, 12) is mounted in a vehicle. The outputs (x(h), y(h)) of the windings are measured for a number of compass directions (headings). From this data an error difference angle (.phi.), from a nominal angle, which actually exists between the output windings is calculated. Preferably a look-up table (21, 39) is created relating actual compass heading (h) to measured sense winding outputs by utilizing the calculated error difference angle (.phi.). This table is then utilized for calculating actual compass heading based on actual measured sense winding outputs. The calculated error angle (.phi.) can also be used to calibrate the compass without creating a look-up table. The calibrated compass compensates for misalignment of the sense windings and provides a more accurate electronic compass without requiring creating a calibration table by orienting the compass in a very large number of exactly known directions.

Abstract: An electronic compass for use in a vehicle includes compensation for attaining a high degree of accuracy without operator intervention or the need to drive the vehicle in a deliberate circular path. An automatic method for accurately determining maximum and minimum voltage values from a flux gate sensor having orthogonal sensing windings is provided that operates continuously to adjust for required changes in both the offset and gain compensation factors. The flux gate sensor is further mounted within the vehicle such that the axis of one of the sensing windings is positioned approximately 45.degree. with respect to the vehicle's longitudinal direction. The angled mounting of the sense winding axis results in strong sensing signals when travelling on most roads. The electronic compass further provides visual representation on the outer peripheral segments of an alphanumeric display to prompt the operator to drive in a circle during a manual compensation mode.

Abstract: Two groups of magnetic field transducers shielded from electric fields and at a known distance from each other are contained in a portable instrument. Each group consists of 3 magnetic field transducers each sensitive to the magnetic field at a single point but according to three orthogonal orientations. Rapid reading of the magnetic field values measured by all 6 coils allows evaluation of the current in a straight electrical conductor relatively near to the apparatus on the basis of the direction and amplitude of the magnetic field vectors measured at the position of each group of 3 coils. Assuming that the conductor under scrutiny is the dominant magnetic influence in the area, the determination of both current and distance of the conductor is exact within a wide range of distances between apparatus and conductor and within a large number of orientations of the apparatus with respect to the conductor because of internal computational compensations performed by a microprocessor.

Abstract: An alignment process is applied to each sensor of an array of three axis magnetic sensors to electronically align the three axes of each sensor after the array has been deployed. The alignment process compensates for each sensor not being aligned perfectly with the earth's N-S, E-W and vertical magnetic field components. A field registration process is applied to each sensor of the array that uses a dipole moment detection and localization process and the alignment process combined with a known calibrated dipole source to define the shape of the array. The present invention improves the performance of the array of sensors in detecting magnetic anomalies by digitally compensating for sensor-to-sensor nonalignment and magnetic interferers within interfering range. The alignment process electronically aligns the three axes of each of the sensors to gain maximum performance from the sensor array.

Abstract: Magnetic compasses may be affected by local disturbances in the magnetic field in their vicinity. These disturbances may be caused by the addition or removal of a metal article concerned with a vehicle in which the compass is mounted, and may also be due to local variations in the Earth's magnetic field. The system described herein compensates for such disturbances in the magnetic field to maintain the accuracy of the magnetic compass by transforming an ellipsoidal locus to a spherical locus at a different orientation in space. For example, a one-shot algorithm is employed in which data collected during a setting maneuver of the vehicle is processed to fit a generalized reduced quadric equation having six or less coefficients rather than the nine calibration points required in the prior art for fitting a generalized quadric equation for an ellipsoid. The present invention thus significantly reduces the processing power required.

Abstract: A fluxgate sensor has a coil body defining a bore and an axis. A coil is wound on the coil body around the axis. A ferromagnetic core is located in the bore and extends beyond either end of the coil, to improve the sensitivity of the sensor. The core may be elongate and have a non-circular profile such as a zig zag pattern. In a gradiometer, the core configuration facilitates balancing of two sensors by either radial or axial adjustment of the core.

Abstract: A system for automatically compensating for changes in permanent magnetism in a vehicle in which a flux-gate compass is installed. Calibration is initially performed by rotating the vehicle through a full circle and determining from the flux-gate outputs the degree of distortion suffered by an ideally circular performance characteristic. Subsequent flux-gate readings are compensated in accordance with parameters generated during calibration. Parameters relating to offset or displacement of the characteristic are automatically and continually updated to compensate for changes in permanent magnetism of the vehicle, such as might be caused by loading or unloading the vehicle.

Abstract: Signals produced by brain activity are measured by each sensor of an array of magnetic and/or electrical sensors external to but proximate to the head (or other portion of the body) of a subject. The measurements obtained simultaneously from all of the sensors are combined in a manner to permit selective measurement of the electrical activity from a specified location within the body, or alternatively, to permit the location in the body producing a particular type of response to be identified. The instantaneous measurement of each sensor is scaled by a weighting coefficient for that sensor, and the products added over all of the sensors. The weighting coefficients are calculated from a mathematical model of the brain that includes information on the shape of the potential source, the extent or type of source activity, the electrical and magnetic properties of the media, and the locations and orientations of the sources and the sensors.

Abstract: A method for the determining route angle and for automatically calibrating course accuracy with a three-axis magnetometer fixed to an aircraft despite the presence of interfering vehicle magnetic fields and instrumentation errors. The method is accomplished in flight and includes numerous computations to compensate the magnetometer's principal error sources. A calibration flight includes specified flight maneuvers (without change of position). The method is particularly suitable for helicopters equipped with three-axis magnetometers.

Abstract: A device is provided for measuring the earth's magnetic field disturbed by anomalies, including a probe in which are mounted, aligned and harmonized with each other, a nuclear magnetic resonance measuring probe associated with its oscillation electronics and the means for compensating for the anomalies due to the carrier: a triaxial magnetometer and a two axis gyrometer. The device can be mounted on land vehicles, ships and aircrafts.