Abstract: Data are input from a geomagnetic sensor that detects magnetic fields in three axial directions, and magnetic field data are measured on the basis of the input data. The measured magnetic field data are sequentially stored, and a determination is made as to whether a plurality of the magnetic field data thus stored lie within a same plane in a three-dimensional orientation space. When it has been determined that the plurality of the magnetic field data lie within the same plane in the three-dimensional orientation space, center coordinates of a circular arc where the stored magnetic field data lie are calculated, as provisional offset values, on the basis of the magnetic field data and in accordance with a predetermined algorithm. Magnetic field data measured after the calculation of the provisional offset values is corrected with the provisional offset values, and an arithmetic operation is performed for determining orientation data on the basis of the corrected magnetic field data.

Abstract: The compass system of the present invention utilizes an improved calibration routine in which a processing circuit of the compass recalibrates the compass each time three data points are obtained from a magnetic field sensor that meet predetermined criteria. One such criterion is that the three data points define corners of a triangle that is substantially non-obtuse. When three data points have been obtained that define a triangle meeting this criterion, the processing circuit calculates a center point for a circle upon which all three data points lie by solving the equation x2+y2+Ax+By+C=0 for A, B, and C, using the coordinate values (x,y) for the three data points and defining the center point as (?A/2, ?B/2).

Abstract: A vehicle compass system for compensating for magnetic disturbances caused by a moveable vehicle accessory includes a magnetic field sensor and a control circuit coupled to the moveable vehicle accessory and the magnetic field sensor. The magnetic field sensor is positioned at a distance from the moveable vehicle accessory and is configured to determine an orientation of the magnetic field sensor with respect to the Earth's magnetic field and to generate magnetic field data.

Abstract: A magnetism detection device includes a geomagnetism detection element for detecting geomagnetism of each transverse axial component and a nonvolatile memory element of a thermal metamorphic type for storing one piece or a plurality of pieces of correction data for correcting the detected geomagnetism values. Each piece of correction data is expressed as a value of a ration of inter-axial correction coefficient to the axial sensitivity correction coefficient of either axis.

Abstract: The disclosure relates to micro-electromechanical systems (MEMS) and magnetic MEMS sensors. The sensors include a substrate having a surface, a first magnetic field detector positioned on the surface, a second magnetic field detector positioned on the surface proximate to the first magnetic field detector, and a third magnetic field detector positioned on the surface proximate to the first and second magnetic field detectors. Each of the first, second and third magnetic field detector is capable of detecting external magnetic fields that are mutually orthogonal along three directions. In certain embodiments, the magnetic MEMS sensors may be useful as electronic compasses. The disclosure also relates to fabricating a magnetic MEMS device, such as an electronic compass, from or on a single wafer, which includes multiple MEMS sensors.

Abstract: An input device using a geomagnetic sensor includes a geomagnetic sensor outputting a voltage corresponding to geomagnetism, and a control part calculating an azimuth using the voltage output from the geomagnetic sensor and calculating the rotation angle by comparing the azimuth to a previously measured azimuth, thereby generating the input signal corresponding to the rotation angle when the input device is tilted within a certain range. Accordingly, unwanted generation of the input signal is prevented when the input device is tilted by more than a certain angle.

Abstract: A compass compensation system is provided for automatically and continuously calibrating an electronic compass for a vehicle, without requiring an initial manual calibration or preset of the vehicle magnetic signature. The system initially adjusts a two axis sensor of the compass in response to a sampling of at least one initial data point. The system further calibrates the compass by sampling data points that are substantially opposite to one another on a plot of a magnetic field and averaging an ordinate of the data points to determine a respective zero value for the Earth magnetic field. The system also identifies a change in magnetic signature and adjusts the sensor assembly.

Abstract: A simple self-contained, hand-held instrument for reading an azimuth or bearing in relation to the earth's magnetic field either out in the field or on the water with substantial accuracy. Means are provided that places the far object into the same focal plane (or focal point) as the close up bearings on the compass disc face, thus allowing the eye to instantly see both images without adjustment between near-sight and far-sight. Means are also provided for the adjustment of the instrument for the local variation or declination of the earth's magnetic field versus that of true north.

Abstract: In a method according to the invention for estimating the accuracy of azimuthal orientations (a) of a measuring device (1) having an electronic magnetic compass (2), a plurality of determinations of an azimuthal orientation (a, a?, a?, a??, a??) are carried out, in which the measuring device is aligned with one and the same measuring points at different measuring locations (P, P?, P?, P??, P??) adjacent to one another. On the basis of these determined azimuthal orientations (a, a?, a?, a??, a??), the value of the accuracy is automatically estimated by the measuring device (1) by means of a computational method. The adjacent measuring locations (P, P?, P?, P??) are advantageously located one above the other or along a straight line to the measuring point. By means of this method, stationary stray fields of local scale can be detected and the effects thereof on the accuracy can be estimated. Further methods according to the invention are designed in each case specifically for further types of stray fields.

Abstract: In a compass sensor unit, an azimuth data computing method is carried out by the steps of: inputting a signal from a geomagnetic sensor to measure magnetic field; determining whether to store measurement data of the magnetic field based on a distance from the last stored measurement data; calculating an offset value based on the stored data; making a comparison for each component of a plurality of measurement data used for calculating the offset value, and judging the offset value to be valid when a difference between the maximum and minimum values of each component is a given value or more; updating the already stored offset value to the offset value judged to be valid; and correcting newly provided measurement data by the updated offset value to compute azimuth data.

Abstract: A method for correcting a vehicle compass measurement for an interfering magnetic field generated by a vehicle accessory, where the interfering magnetic field has an intensity sufficient to cause a compass measurement error, includes monitoring the operation of the vehicle accessory and detecting a characteristic of operation of the vehicle accessory. A measurement or timing signal is then generated based on the characteristic of operation. A magnetic field for direction is measured in response to the measurement signal and an offset or correction value is determined based at least one the measured magnetic field and the characteristic of operation of the vehicle accessory.

Abstract: A structure and associated method to accurately read an encoder tape in an encoder system. The encoder system comprises, a read head, a shoe structure adjacent the read head, and an encoder tape. The encoder tape is adapted to be read by the read head. The shoe structure is adapted to locally support the encoder tape and locally dampen a vibration of the encoder tape as the encoder tape is read by the read head.

Abstract: A magnetic compass includes: a three-axis magnetic sensor for detecting geomagnetic vector as geomagnetic components in directions of three orthogonal axes x, y, and z; a data-plane calculating unit for calculating a data plane on which output data of the three-axis magnetic sensor are present in a sensor coordinate system of the three axes x, y, and z; a unit vector calculating unit for calculating unit vectors of a horizontal coordinate system of three orthogonal axes X, Y, and Z whose Z-axis runs vertically and X-Y plane defines a horizontal plane relative to the earth; a horizontal coordinate system conversion unit for converting geomagnetic components in the sensor coordinate system detected by the three-axis magnetic sensor into geomagnetic components in the horizontal coordinate system; an azimuth calculating unit for calculating azimuth based on the converted geomagnetic components in the horizontal coordinate system; and a display unit for displaying the calculated azimuth.

Abstract: A magnetism detecting device includes a magnetometric sensor, a bias magnetic field generating unit, a voltage applying unit, a detecting unit, and an operating unit. The detecting unit calculates a first output corresponding to a difference between two voltage values each corresponding to the positive and negative bias magnetic fields, and the positive voltage; and a second output corresponding to a difference between two voltage values each corresponding to the positive and negative bias magnetic fields, and the negative voltage. The detecting unit eliminates an offset voltage included in the first output and the second output by taking difference between the first output and the second output.

Abstract: An electronic compass assembly includes a first collection portion and a second collection portion that each collect magnetic field data. The magnetic field data collected by the second collection portion partially overlaps the magnetic field data collected by the first collection portion. A processor module determines a calibration output based upon the magnetic field data from the first collection portion if a first predetermined condition exists and determines the calibration output based upon magnetic field data from the second collection portion if a second predetermined condition exists. An example method for controlling the electronic compass includes calibrating the electronic compass based upon one of a first magnetic field data set or a second, partially overlapping magnetic field data set.

Abstract: A portable terminal apparatus is mounted in a casing and has a magnetic sensor that detects a magnetic field around the casing with an offset and outputs magnetic data representing the detected magnetic field, and a tilt sensor that detects a tilt of the casing and sequentially outputs tilt data representing the detected tilt. In the portable terminal apparatus, a capture part sequentially captures the magnetic data from the magnetic sensor at a given time interval. A calculation part calculates the offset of the magnetic sensor based on a plurality of the magnetic data sequentially captured by the capture part. A detection part detects an orientation variation of the casing based on the tilt data sequentially outputted from the tilt sensor. A change part changes the time interval for sequentially capturing the magnetic data in accordance with the detected orientation variation.

Abstract: A method for controlling an electronic compass includes receiving raw magnetic field data into a calibration module and determining a calibration output based upon the raw magnetic field data. The raw magnetic field data is also received into a compass heading module for determining compass heading outputs based upon the raw magnetic field data. The calibration module filters the raw magnetic field data and validates the calibration outputs independently from output data filtering and results validation in the compass heading module.

Abstract: Data are input from a geomagnetic sensor that detects magnetic fields in three axial directions, and magnetic field data are measured on the basis of the input data. The measured magnetic field data are sequentially stored, and a determination is made as to whether a plurality of the magnetic field data thus stored lie within a same plane in a three-dimensional orientation space. When it has been determined that the plurality of the magnetic field data lie within the same plane in the three-dimensional orientation space, center coordinates of a circular arc where the stored magnetic field data lie are calculated, as provisional offset values, on the basis of the magnetic field data and in accordance with a predetermined algorithm. Magnetic field data measured after the calculation of the provisional offset values is corrected with the provisional offset values, and an arithmetic operation is performed for determining orientation data on the basis of the corrected magnetic field data.

Abstract: An example method for controlling an electronic compass includes determining compass tracking angles in a coordinate system for magnetic field data points that correspond to magnetic field sensor signals produced as a vehicle rotates relative to a surrounding magnetic field. The magnetic field data points produce an expected curve in the coordinate system. The rotation of the vehicle is tracked relative to the surrounding magnetic field based upon the compass tracking angles and whether the vehicle has rotated a desired amount is determined based at least partially upon the expected curve and the compass tracking angles.

Abstract: Method and system to detect orientations of a moving object using one or more magnetic compasses. The method and system minimize magnetic field interference in a space where an object is moving such that the orientations of the moving object can be precisely detected. The method includes setting one or more earth magnetic field (EMF) conditions without a magnetic field interference component to determine whether the one or more magnetic compasses are located in an EMF area, calculating a magnitude of a magnetic field applied to the moving object using the one or more magnetic field compasses, and detecting an orientation of the moving object by determining whether the calculated magnitude of the magnetic field satisfies the one or more EMF conditions.

Abstract: A method is designed for measuring a magnetic offset of a geomagnetic sensor equipped in a portable information terminal apparatus having a storage. The geomagnetic sensor has a magnetic sensitivity to a geomagnetic field and is affected by magnetization to cause the magnetic offset. In the method, an output of the geomagnetic sensor is measured to successively provide measurement data of the geomagnetic field from the output of the geomagnetic sensor. The measurement data is stored in the storage. The measurement data is read out from the storage when a number of the measurement data stored in the storage reaches a predetermined number, and an offset value of the magnetic offset is estimated based on the predetermined number of the measurement data read out from the storage.

Abstract: In an azimuth/inclination-angle detection apparatus, a measurement data obtaining unit obtains first and second measurement data sets g and h from acceleration and magnetic sensors, respectively. A first computation unit calculates an azimuth ?0, an elevation angle ?0, and a geomagnetism depression angle ?0 from the measurement data sets g and h. An averaging unit accumulates and averages the geomagnetism depression angle ?0 so as to obtain a value to be used as a geomagnetism depression angle ?. A second computation unit calculates an azimuth ? and an elevation angle ? from the second measurement data set h and the geomagnetism depression angle ?. When a plurality of solutions exist, they are stored as candidates (?1, ?1) and (?2, ?2). A selection unit selects a detection value (?, ?) from the candidates (?1, ?1) and (?2, ?2) with reference to the above-described values ?0 and ?0 serving as reference values.

Abstract: A geomagnetic sensor and method are provided. The geomagnetic sensor has a geomagnetic detection module for outputting an electric signal value corresponding to a geomagnetism, a tilt detection module for detecting a tilt angle with reference to a reference plane, a memory for storing a constant for each azimuth angle, and a central processing unit for performing a first azimuth computation using an initial value of the constants, the electric signal value and the tilt angle, and for performing a second azimuth computation by detecting from the memory a constant corresponding to the resultant azimuth of the first azimuth computation and using the detected constant. The method includes outputting an electric signal corresponding to a geomagnetism; normalizing the output electric signal; detecting a tilt angle with respect to a reference plane; performing a first azimuth computation; detecting a constant corresponding to the resultant azimuth; and performing a second azimuth computation.

Abstract: A mobile terminal apparatus 1 uses an acceleration sensor as a tilt angle sensor 24, and realizes various applications based on this detection result. A processing unit 10 counts the number of steps of a human based on acceleration components of low frequency detected by the tilt angle sensor that detects the acceleration components. At that time, the acceleration component of an axis among three axes which most approximates a gravity axis is mainly used. A viewpoint relative to a three-dimensional object or a three-dimensional space displayed on a display unit 36 is moved. By effectively utilizing the detection result of the tilt angle sensor, it is possible to realize a mobile terminal apparatus 1 featuring greater usefulness.

Abstract: There is provided a quadrilateral insulating substrate, and plural magnetic sensors are provided on the substrate. An IC is provided on the substrate for supplying driving signals to the magnetic sensors and receiving magnetic detecting signals from the magnetic sensors to output magnetic information depending on strength of magnetism. The magnetic sensors and the IC are encapsulated by an encapsulation member to integrate the substrate and magnetic sensors and IC.

Abstract: The compass system of the present invention utilizes an improved calibration routine in which a processing circuit of the compass recalibrates the compass each time three data points are obtained from a magnetic field sensor that meet predetermined criteria. One such criterion is that the three data points define corners of a triangle that is substantially non-obtuse. When three data points have been obtained that define a triangle meeting this criterion, the processing circuit calculates a center point for a circle upon which all three data points lie by solving the equation x2+y2+Ax+By+C=0 for A, B, and C, using the coordinate values (x,y) for the three data points and defining the center point as (?A/2, ?B/2).

Abstract: A geomagnetic sensor for auto-calibration of a deviation and a method of using the geomagnetic sensor. The geomagnetic sensor includes a geomagnetic detector including X-axis and Y-axis fluxgates orthogonal to each other and receiving a drive signal to detect an electromotive force corresponding to a geomagnetism, a signal processor converting the electromotive force output from the geomagnetic detector into X-axis and Y-axis output values and outputting the X-axis and Y-axis output values, and a drive signal generator applying the drive signal to the geomagnetic detector. Each of the X-axis and Y-axis fluxgates includes cores, a solenoid type exciting coil, and at least two detection coils winding around the cores in a solenoid form. Accordingly, as an azimuth is measured using output values detected by the separated detection coil, the azimuth can be exactly and easily detected regardless of an external magnetic field.

Abstract: A geomagnetic sensor which informs a user that information with respect to a distorted azimuth angle may be detected. The geomagnetic sensor includes a geomagnetism detection module including an X axis fluxgate and a Y axis fluxgate orthogonal to each other and detecting a predetermined amount of electrical signals corresponding to a geomagnetism of each of the fluxgates; a signal processing unit for converting the electrical signal output from the geomagnetism detection module to predetermined X axis and Y axis output values and outputting them; a display unit for displaying a predetermined warning message on a screen; and a control unit for determining whether the output values of the X and Y axes are distorted, and controlling the display unit to display the predetermined warning message upon determination that the output values are distorted. Accordingly, the possibility of a distorted azimuth angle may be detected and informed to a user.

Abstract: A geomagnetic sensor supporting a dip angle detection function. The geomagnetic sensor includes a rotation angle measurement part for measuring pitch and roll angles of the main body with respect to the surface of the Earth; a geomagnetic measurement module for outputting an electric signal corresponding to the geomagnetic field; a memory for storing predetermined reference azimuths and output values of the geomagnetic measurement module corresponding to changes of the pitch and roll angles; and a controller for calculating azimuths by use of the output values of the geomagnetic measurement module, the pitch and roll angles, and predetermined dip angles. The controller establishes at least two dip angles, calculates the azimuth for each dip angle, compares the azimuth to the reference azimuth, and determines a dip angle at the azimuth having a smaller azimuth error as a current dip angle. The geomagnetic sensor can measure a precise dip angle using a simple method.

Abstract: There is provided an electronic device having a built-in compass, comprising: a processing unit for controlling functions of the electronic device; an input device for giving control commands; an acceleration sensor for measuring tilt angle of the electronic device. The processing unit is configured to set a horizontal condition required for the built-in compass, the horizontal condition indicating admissible values of tilt angle of the electronic device, to detect activation of a navigation application on the basis of the input device, to send a control command to the acceleration sensor for measuring a tilt angle of the electronic device when activation of the navigation application is detected, to compare the measured tilt angle with the horizontal condition for the built-in compass, and to calculate a compass direction when, on the basis of the comparison, it is detected that the electronic device meets the horizontal condition required.

Abstract: Provided a method and apparatus for using a magnetic field. The method includes: measuring and storing magnetic field data indicating magnitudes of a magnetic field in different directions at each time by rotating sensors over a space; and checking whether a disturbance of the magnetic field exists, using curve fitting parameters such as amplitude and offset of at least one of magnetic field trajectories formed by the stored magnetic field data.

Abstract: A geomagnetic sensor includes a geomagnetic detection module configured to output an electrical signal having a magnitude corresponding to a magnetic field; a memory configured to store an azimuth measured in a horizontal plane; an accelerometer module configured to measure a tilt at present, and to compute a tilt angle therefrom; and a controller configured to calculate a dip angle by using the electrical signal outputted from the geomagnetic detection module, the tilt angle, and the horizontal azimuth. A method for detecting a dip angle by a geomagnetic sensor includes outputting an electrical signal having a magnitude corresponding to an external geomagnetic field; detecting an azimuth in a horizontal plane and storing the detected azimuth; measuring a tilt at present and computing a tilt angle thereof; and calculating a dip angle by using the electrical signal, the tilt angle, and the azimuth measured in the horizontal plane.

Abstract: A method for characterizing distortions in the earth's magnetic field caused by a vehicle having a magnetometer affixed therein is described. The method includes repeatedly measuring the distorted magnetic field utilizing the magnetometer and obtaining a three-dimensional orientation of the vehicle axes with respect to the earth at a time of each magnetometer measurement. The method also includes receiving undistorted earth magnetic field data for the vicinity of the vehicle relative to the earth at the time of each magnetometer measurement and characterizing distortions caused by one or more of the vehicle and magnetometer errors utilizing the magnetic field measurements, the orientations of the vehicle, and the undistorted earth magnetic field data.

Abstract: The compass system of the present invention utilizes an improved calibration routine in which a processing circuit of the compass recalibrates the compass each time three data points are obtained from a magnetic field sensor that meet predetermined criteria. One such criterion is that the three data points define corners of a triangle that is substantially non-obtuse. When three data points have been obtained that define a triangle meeting this criterion, the processing circuit calculates a center point for a circle upon which all three data points lie by solving the equation x2+y2+Ax+By+C=0 for A, B, and C, using the coordinate values (x,y) for the three data points and defining the center point as (?A/2, ?B/2).

Abstract: A direction indicating device in which a current display direction is determined in consideration of the historical information of a direction of vehicle specified by a direction specifying unit 1 and a previous display direction, to be specific, in a case where the current direction of vehicle specified by the direction specifying unit 1 agrees with a previous direction of vehicle, the current display direction is changed to agree with the current direction of vehicle, and in a case where the current direction of vehicle specified by the direction specifying unit 1 is different from the previous direction of vehicle, the current display direction is made to agree with the previous display direction.

Abstract: A method for measuring a directional of a body in a three-dimensional space defined by an X-axis (magnetic north), a Y-axis, and a Z-axis is proposed. A geomagnetic force along an x-axis, which is the direction towards which the body points and an x-axis tilt angle, which is an angle between the horizontal plane and the x-axis, are detected. The x-axis tilt angle is determined as a rotation angle, which an angle by which the x-axis needs to be rotated around the Y-axis so as to be in the XY-plane. An azimuth of the body is calculated from the geomagnetic force and the rotation angle.

Abstract: Provided are an apparatus and method of calibrating azimuth of a mobile device. The apparatus includes: a magnetic field measuring unit having a plurality of magnetic sensors aligned in a constant angle interval on the mobile device and measuring magnetic field data indicating magnitudes of a magnetic field in different directions; and a controller generating a calibration table indicating a correspondence between an actual magnetic field trajectory formed by the magnetic field data and a theoretical magnetic field trajectory and calibrating azimuth of the mobile device using the calibration table.

Abstract: A compass device includes a platform defining an xz-plane and an x-axis. A first accelerometer is coupled to the platform at an angle such that the first accelerometer is sensitive to movement of the first accelerometer in the xz-plane. The first accelerometer includes a first flexure plate generating a first accelerometer signal in response to movement of the first flexure plate. A second accelerometer is coupled to the platform at an angle such that the second accelerometer is sensitive to movement of the second accelerometer within the xz-plane. The second accelerometer includes a second flexure plate generating a second accelerometer signal in response to movement of the second flexure plate. A processor receives the first accelerometer signal and the second accelerometer signal and generates a platform control signal, thereby rotating the platform in response to an inequality between the first accelerometer signal and the second accelerometer signal.

Abstract: The present invention aims to achieve that geomagnetism can be sensed in high precision while eliminating an adverse influence by magnetic noise with respect to a geomagnetic sensor provided in a housing, and correct azimuth information can be acquired. A portable terminal apparatus according to the present invention is arranged by that both a first housing (11) and a second housing (12) are coupled to each other by way of a hinge portion (13) under pivotable condition, a geomagnetic sensor (33) is provided on a circuit board (32) in the second housing (12), and also, a speaker (19) is provided on the side of a rear surface thereof. Both this geomagnetic sensor (33) and a speaker (19) corresponding to a component for generating magnetic noise which gives an adverse influence with respect to the geomagnetic sensor (33) are provided in the vicinity of each other within the same second housing (12), and both the members are arranged on the same plane.

Abstract: A compass system comprises an electronic compass capable of providing a raw compass reading, at least one adjustment factor relating to a position of the electronic compass, and a compensation device selectively providing a compensated compass reading based on the raw compass reading and the adjustment factor. Further, at least one adjustment factor relating to the position of the electronic compass is defined and may be stored in a memory.

Abstract: A digital display compass for mounting on vehicle rear view mirrors, including a direction sensor module generating signals corresponding to a direction that it is facing attached to the inside of the vehicle windshield, an electronic housing attached to the back side of the rear view mirror, and a digital display attached to the front side of the rear view mirror. A flexible transmission cord extends from the directional sensor module to the electronic housing, and transmits the signals from the direction sensor module. The electronic housing contains a battery power source and electronics for converting the signals received from the transmission cord to drive a digital display representative of the direction sensed by the direction sensor module. A flexible cable extends from the back side of the mirror to the front side of the mirror and provides electronic communication from the electronic housing to the digital display.

Abstract: The compass system of the present invention utilizes an improved calibration routine in which a processing circuit of the compass recalibrates the compass each time three data points are obtained from a magnetic field sensor that meet predetermined criteria. One such criterion is that the three data points define corners of a triangle that is substantially non-obtuse. When three data points have been obtained that define a triangle meeting this criterion, the processing circuit calculates a center point for a circle upon which all three data points lie by solving the equation x2+y2+Ax+By+C=0 for A, B, and C, using the coordinate values (x,y) for the three data points and defining the center point as (?A/2, ?B/2).

Abstract: A system, method, device and computer code product is disclosed for stabilizing compass heading under tilt error conditions from an uncorrected electronic compass reading. Exemplary embodiments include a stabilizing filter configured to filter out tilt errors incorporated into the uncorrected electronic compass reading and a filter adaptation module configured to control the stabilizing filter response based on the signal radius of the uncorrected compass reading and a pre-calibrated ideal radius for the compass. The filter adaptation module can be configured to calculate a filter response parameter as a function of the relative difference between the signal radius of the uncorrected compass reading and the pre-calibrated ideal radius. The filter response parameter can be passed to the stabilizing filter for controlling its operation.

Abstract: A method of finding a dip angle in a tilt-compensated electronic compass includes the steps of a) setting a predetermined azimuth angle indicative of a horizontal status of a geomagnetic sensor to a reference azimuth angle; b) if the compass is slightly tilted, stepwise-increasing a dip angle within a predetermined dip angle search range, and calculating azimuth angles associated with individual dip angles; c) comparing the calculated azimuth angles with the reference azimuth angle, and finding one azimuth angle, which is closest to the reference azimuth angle, among the calculated azimuth angles; and d) setting the dip angle applied to the closest azimuth angle to a specific dip angle associated with a corresponding azimuth angle, such that a more accurate azimuth angle can be detected by the on the basis of the calculated dip angle.

Abstract: In a signal processor for use in an electronic compass for controlling an offset voltage generated in an analog signal process and automatically controlling an amplification gain, an analog signal processor 52 amplifies signals Sx and Sy, and controls an offset voltage and amplitude A generated during an amplification process. An analog/digital (AD) converter 53 converts analog signals Vadcx and Vadcy from the analog signal processor 52 into a digital signal. A digital signal processor 54 measures a maximum value Vadc—max and a minimum value Vadc—min associated with the digital signal from the AD converter 53, and outputs, to the analog signal processor 52, an offset control signal Soc and a gain control signal Sgc based on the maximum value Vadc—max and minimum value Vadc—min. The signal processor can maintain levels of signals, to be inputted into the AD converter, to be within a reference voltage range.

Abstract: An electronic compass system includes a magnetic sensor circuit having at least two sensing elements for sensing perpendicular components of the Earth's magnetic field vector. A processing circuit is coupled to the sensor circuit to filter, process, and compute a heading. The processing circuit further selects an approximating geometric pattern, such as a sphere, ellipsoid, ellipse, or circle, determines an error metric of the data points relative to the approximating pattern, adjusts the pattern to minimize the error, thereby obtaining a best fit pattern. The best fit pattern is then used to calculate the heading for each successive sensor reading provided that the noise level is not noisy and until a new best fit pattern is identified. The electronic compass system is particularly well suited for implementation in a vehicle rearview mirror assembly.

Abstract: A compass compensation system is provided for automatically and continuously calibrating an electronic compass for a vehicle, without requiring an initial manual calibration or preset of the vehicle magnetic signature. The system initially adjusts a two axis sensor of the compass in response to a sampling of at least one initial data point. The system further calibrates the compass by sampling data points that are substantially opposite to one another on a plot of a magnetic field and averaging an ordinate of the data points to determine a respective zero value for the Earth magnetic field. The system also identifies a change in magnetic signature and adjusts the sensor assembly.

Abstract: A method and system is presented for acquiring calibration data for a three-axis electronic compass by positioning and rotating the compass so that each sensitive axis in the compass experiences variation in the magnetic field while rotating the compass. Acquiring the calibration data occurs by measuring output signals that reflect the magnetic fields acting on the electronic compass while rotating the compass. Positioning of the compass includes moving the compass so that at least one of the sensitive axes travels a path that approximately forms a cone when the compass is rotated around a gravity vector. Calibration data from three sensitive axes experiencing variation in the magnetic field is available during a single rotation of the compass.

Abstract: An automatic calibration method for use in an electronic compass. Using the automatic calibration method, the electronic compass automatically calculates and corrects offset and scale values of a geomagnetic signal by detecting one rotation of a geomagnetic axis during a predetermined period of time. The electronic compass calculates an azimuth angle upon receiving geomagnetic data from the geomagnetic sensor, and finds maximum and minimum values of sensor signals of individual axes of the geomagnetic sensor using the received geomagnetic data such that it can correct or calibrate deviation of the azimuth angle. When a time consumed for calibration is the same or shorter than a maximum calibration effective time, the electronic compass determines whether a current state of the detected entry signal indicates a predetermined steady-state flow.

Abstract: A method for characterizing distortions in the earth's magnetic field caused by a vehicle having a magnetometer affixed therein is described. The method includes repeatedly measuring the distorted magnetic field utilizing the magnetometer and obtaining a three-dimensional orientation of the vehicle axes with respect to the earth at a time of each magnetometer measurement. The method also includes receiving undistorted earth magnetic field data for the vicinity of the vehicle relative to the earth at the time of each magnetometer measurement and characterizing distortions caused by one or more of the vehicle and magnetometer errors utilizing the magnetic field measurements, the orientations of the vehicle, and the undistorted earth magnetic field data.