Abstract: A sourceless orientation sensor having an azimuthal sensor which determines the azimuthal orientation relative to a planetary magnetic field, and a tilt sensor which determines the direction and magnitude of the displacement from vertical using the planetary gravitational field. The tilt sensor includes a transparent gas and a transparent viscous fluid in a spherical shell, a light emitting diode (LED) mounted at the top of the shell, and four photodetectors mounted at the bottom of the shell. As the tilt sensor is rotated the path of the light cone emanating from the LED and refracting at the gas/fluid interface is altered, thereby altering the intensity of light incident on the photodetectors. The magnitude of the light incident on the photodetectors is processed to provide the tilt angles. A thin transparent disk floats at the gas/fluid interface to damp surface waves caused by reorientation of the device.

Abstract: Provided is a magnetomoter apparatus for measuring low-level magnetic fields. The magnetometer utilizes a coil pair wound on cores of a high permeability material. These coils are driven to magnetic saturation by an energizing circuit, and develop a uniquely shaped distortion spike in their back emf having an amplitude which is directly related to the ambient magnetic field. The resulting back emf of the coils can be compared and processed to generate a measurement of the ambient magnetic field.

Abstract: A sensor for detecting a magnetically permeable mass by the disturbance of the earth's magnetic field in the vicinity of the sensor comprises a ferromagnetic strip with a conductive winding wrapped thereabout, a means for magnetically biasing the strip such that regardless of orientation the earth's magnetic field and the strip placing the ferromagnetic strip in a position on its BH curve where the slope is substantially linear, a means for generating an analog signal indicative of the inductance of the winding as the earth's magnetic field is disturbed in the vicinity of the ferromagnetic strip causing a change in the inductance of the winding, a means for digitizing the analog signal at spaced time intervals to produce a series of digitized values, and a digital computer means for processing the digitized signal values to characterize the presence and/or motion of the permeable mass.

Abstract: A variable reluctance saturable core proximity sensor assembly comprising a target and a sensor. The target consists of a magnet having a high field strength, a base plate having a high relative permeability, and a nonmagnetic metal housing surrounding the magnet and base plate. The sensor consists of a core made from a material having a high relative permeability, a coil surrounding the core and a housing made from a nonmagnetic material surrounding the core and coil. At its distal end of the core is a flux director that intercepts the magnetic field produced by the target. The flux director comprises a plurality of radially extending arms having the same permeability as the core. The flux director has a cross-sectional area selected so that the flux director and core saturate at substantially the same time. The sensor assembly may be used in either a slide-by or head-on mode.

Abstract: Apparatus and method for detecting the presence of extraneous magnetic fields having a predetermined weak magnitude include a transformer having an excitation winding, an output winding, and a saturable core which will saturate in a magnetic field of a predetermined saturation magnitude. The core is made of amorphous metal alloy and is shaped to cancel the electromagnetic effects of magnetic fields having flux lines which are substantially parallel with respect to the transformer. An excitation circuit is connected to the excitation winding for generating a magnetic field having an excitation magnitude of lesser magnitude than the saturation magnitude of the core. The excitation magnitude and the weak magnitude of the extraneous magnetic fields combine to create a magnetic field of greater magnitude than the saturation magnitude of the core. A detector circuit is connected to the output winding for detecting and indicating saturation of the core.

Abstract: An apparatus is disclosed for manipulation by an operator or user for detecting magnetically detectable plastic pipe and other sources of magnetic fields from a distance having a horizontally oriented support member with a handle extending at an acute angle therefrom. A magnetic field gradiometer comprising a hollow non-magnetic tube with two flux-gate magnetometers therein is supported at the distal end of the support member a substantial distance ahead of the operator in a substantially vertical position. A microprocessor is supported on the support member operatively connected through a differential amplifier to the gradiometer for processing signals therefrom. An electronic read-out module is supported on the handle spaced from the gradiometer and operable to receive signals from the microprocessor and convert them into an audible or visual display to be sensed by the operator or user.

Abstract: A magnetism detecting apparatus of this invention includes a magnetic sensor (11) constituted by a ferromagnetic core (12) and a detection coil (13) wound around the core (12), a parallel resonance circuit (15) constituted by the detection coil (13) of the magnetic sensor (11) and a capacitance element (14) connected in parallel with the detection coil (13), an oscillation circuit (18), which is constituted by an amplifier (16) to which the parallel resonance circuit (15) and a resistor (17) are connected as a feedback circuit, and the parallel resonance circuit (15), and excites the core (12) to a saturation region by using an oscillation current, and a waveform change detecting circuit (22, 24) for detecting a change in waveform of an output signal from the oscillation circuit (18).

Abstract: Device for measuring intensity of magnetic field, displacement, speed and acceleration of magnetized and ferromagnetic objects in external magnetic field including source of external magnetic field, sensor sensing intensity of magnetic field and having toroid type ferromagnetic core, primary and secondary windings, circuitry for activating primary winding with alternative current, circuitry for detecting and measuring peak voltage of the output pulses at the secondary winding, components controlling intensity of external magnetic field. Displacement of controlled objects in external magnetic field changes intensity of the magnetic field near the sensor. This displacement is measured by measuring peak voltage of the output pulses. The alternative current in primary winding induces positive and negative output pulses in secondary winding, remagnetizing the core along the hysteresis loop.

Abstract: A device is disclosed for measuring low-flux magnetic fields with a sensor operating according to the core saturation principle. The sensor is provided with a ferromagnetic core, an excitation coil and a measuring coil. The measuring coil, the excitation coil and the ferromagnetic core are electrically insulated from one another, each being disposed in a single, separate, parallel layer on a support material.

Abstract: A device is disclosed for detecting the presence and/or determining the configuration of a magnetic substance. The device includes a magnetic circuit having a magnetic core and an air gap. Coupled to the magnetic circuit are an excitation coil, for periodically driving the magnetic circuit into saturation, and a measurement coil, for measuring the effective appearing permeability of the magnetic circuit in the presence of the magnetic substance.

Abstract: A single core triaxial flux-gate magnetometer including a tall-toroidal core having a radial excitation winding, two orthogonal sets of axial or circumferential output windings, and an equatorial output winding oriented orthogonal to both axial output windings. The core is fabricated from a strip of magnetic tape material wrapped to form a toroid having a height approximately equal to its diameter. Each end of the strip is uniformly tapered along the top and bottom edges such that the tapered segments extend around an integer multiple of complete revolutions of the wrapping, the length of each tapered segment thereby being equal to the inner or outer circumference of the toroid or an integer multiple thereof.

Abstract: A magnetic field generating member is attached to a rotable object the angle of which is to be detected. The apparatus includes first and second magnetic sensors located in the magnetic field generated by the magnetic field generating member, first and second detectors for generating first and second sine wave singles responsive to outputs of the first and second magnetic sensors, first and second limiters for limiting the first and second sine wave signals; and, a synthesizing circuit for synthesizing outputs of the first and second limiter to thereby obtain a synthesized output.

Abstract: A magnetometer technology is provided based on a simple axial sensor which operates using the non-linear nature of saturating magnetic core material. The sensor appears electrically as an inductor with a non-linear inductance that varies both with magnetic field applied externally and the field created by the coil current. By using this sensor as the inductor of an LR relaxation oscillator, a change in applied magnetic field will cause a change in inductance, which will in turn cause a change in the oscillator period. The period of the oscillator can be converted to a digital form by using simple counting techniques. By introducing an enhancement of this scheme whereby two different periods are measured with different oscillator characteristics, the magnetometer will have no output drift when no field is applied.

Abstract: A magnetic field detecting device, particularly for detecting the earth's magnetic field, includes one or more amorphous or microcrystalline magnetic fibres having two bistable magnetization states and surrounded by one single measuring coil (103). The measuring coil is supplied with a periodically changing control signal (101a) which is superposed with a detected signal (103a) contingent on the sensed magnetic field. The detected signal is caused to control a flip-flop (122) which influences the working direction of an integrator (101), the output signal of which forms a performance signal in addition to forming said control signal. The performance signal (101c, 106a) is processed in a microprocessor (107), to which a control signal (122b) is also delivered from the flip-flop, and is able to restart the circuit when a control signal fails to appear.

Abstract: A high sensitivity magnetic field sensor comprises a high permeability magnetic circuit (10) and excitation means (L.sub.e) for periodically saturating the magnetic circuit. Two identical windings (L.sub.1, L.sub.2) are symmetrically wound around symmetrical parts (A, B) of the magnetic circuit. Identical first and second capacitors (C.sub.1, C.sub.2) are respectively connected to the terminals of the windings. The voltages on the windings determine the value of the magnetic field.

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: A magnetic detection apparatus (magnetic locator) comprises a housing constituted by a first integral molded plastic unit and a second integral molded plastic unit that are joined. The first unit has a tube with a plate at one end thereof transverse to the length of the tube, the plate having an opening through which a magnetic sensor assembly is inserted into the tube. The second unit has a cover open at one end and having a tubular handle at the opposite end, by which the user may grasp the apparatus. Attachment of the cover to the plate closes the open end of the cover to provide a casing. Magnetic sensors are mounted on a channel or angle structural member that is rigidly attached to the chassis of an electrical unit mounted in the casing. Sound from a loudspeaker mounted on the chassis is transmitted through the handle to the exterior of the apparatus. The chassis also supports a meter that is visible through an opening in an end wall of the cover adjacent to the handle.

Abstract: An apparatus detects a magnetic tag implanted in an organism as detector is moved past the organism by detecting a magnetic field difference between two positions. Prior to examination of a specimen under test, the outputs of a plurality of loops detecting magnetic fields are balanced in a uniform magnetic field. As a consequence, when one of the coils is exposed to a different magnetic field than the other of the coils this difference is detected and an alarm is sounded to indicate that the magnetic tag has been detected.

Abstract: A magnetometer having only a single coil winding for sensing the magnetic field along a single axis. Functionally, the invention comprises an oscillator, an integrator, and a voltage-controlled current source. The oscillator uses a saturating inductor which also serves as the magnetic-field-sensing element. The inductor is driven with a positive voltage and when the current through the inductor exceeds a value which indicates that the core is saturated, the driving voltage switches to an equal-magnitude negative value. This negative drive is maintained until the current again indicates the core to be saturated, at which point the driving voltages switches back to the positive value. With no externally applied field, the inductor current averages to a zero value. An externally applied field helps the core saturate in one direction and hinders it in the other, resulting in a change in average inductor current.

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 magnetic detection apparatus (magnetic locator) comprises a housing constituted by a first integral molded plastic unit and a second integral molded plastic unit that are joined. The first unit has a tube with a plate at one end thereof transverse to the length of the tube, the plate having an opening through which a magnetic sensor assembly is inserted into the tube. The second unit has a cover open at one end and having a tubular handle at the opposite end, by which the user may grasp the apparatus. Attachment of the cover to the plate closes the open end of the cover to provide a casing. Magnetic sensors are mounted on a channel or angle structural member that is rigidly attached to the chassis of an electrical unit mounted in the casing. Sound from a loudspeaker mounted on the chassis is transmitted through the handle to the exterior of the apparatus. The chassis also supports a meter that is visible through an opening in an end wall of the cover adjacent to the handle.

Abstract: A magnetometer and method for measuring magnetic field strength particularly adapted for use in an electronic flux gate compass. A core of magnetic material in the shape of a toroid is coupled to a drive coil and to two sense coils oriented along orthogonal axes. A current limited, current source coupled to the drive coil periodically saturates the core, drives the core out of saturation at an intermediate current level, and saturates the core again. Each sense coil is coupled to a sense circuit which measures the current in the sense coil induced by the periodically changing flux density in the coil resulting from an external magnetic field coupled to the sense coil, produces a dc feedback signal to cancel out the external magnetic field, and provides the dc signal as an output representative of the external magnetic field strength along the axis of the sense coil. The dc signal is produced by synchronously detecting the amplified ac current in the sense coil.

Abstract: The effects of non-equal saturation spikes in a magnetic oscillator magnetometer utilizing a magnetic core sensing inductor are compensated by adding the average inductor current to both the high and low current magnitude limits. In particular, each of the current limits is selected to be a fixed current (which is greater than that required to saturate the core) offset by the average current flowing in the core.The effects of magnetic core hysteresis and series resistance between the inductor and its drive sources are compensated by controlling the drive voltage levels so that the time during which the inductor is driven by current in one direction is equal to the time during which it is driven by current in the other direction.

Abstract: A device for measuring a weak magnetic field is disclosed. The device includes a substrate, a magnetic core having a high magnetic permeability and in the form of a surface film on a substrate, and at least two coils magnetically coupled to the magnetic core. A pulse generator is connected to one of the coils and is used to drive the magnetic core into intermittent saturation. The other coil is used to generate an output signal. The device can be used for measuring the weak magnetic fields associated with bank notes for identifying the values of the bank notes.

Abstract: A roll-independent magnetometer which may be used for example in a towed array magnetometer system comprises a first magnetic field sensor having iso-angular flux sensitivity about a roll axis and a second magnetic field sensor having sensitivity along the roll axis, the arrangement being such that a component of a magnetic field along the roll axis is measured by the second unidirectional sensor and the component of the field lateral to the roll axis is measured by the first sensor. Corrections may be applied for the inclination of the sensor and the angle of dip of the Earth's field. The angle of dip may be measured either in the towing vessel, in the towed body, or provided in look-up tabulated form.

Abstract: A device for measuring a magnetic field which is constant or varies over time, includes at least one core (3, 4) consisting of a material having high permeability, a coil (5, 6) for the magnetization of this core via an alternating current source (I) connected to the coil, and at least one measuring coil (7, 8) in which a voltage is induced corresponding to the magnetic field resulting in the coil produced by means of the applied alternating current and the external magnetic field to be measured. In order to measure very small magnetic fields and relative changes in the fields, an integrating device (9) connected with the measuring coil (7, 8), an arrangement for subtracting the d.c. voltage component from the alternating voltage component of the measurement voltage (U.sub.ai) and a device for detecting the peak values of consecutive half-waves of the output signal (U.sub.x) of the subtracting arrangement (13, 10) are provided.

Abstract: A device for measuring a weak magnetic field is disclosed. The device includes a substrate, a magnetic core having a high magnetic permeability and in the form of a surface film on a substrate, and at least two coils magnetically coupled to the magnetic core. A pulse generator is connected to one of the coils and is used to drive the magnetic core into intermittent saturation. The other coil is used to generate an output signal. The device can be used for measuring the weak magnetic fields associated with bank notes for identifying the values of the bank notes.

Abstract: A current sensor having an element made of amorphous magnetic metal is disclosed herein. The current sensor includes an element located near a conductor and made of amorphous magnetic metal whose magnetic property varies in accordance with the intensity of a magnetic field generated from a current flowing through the conductor, magnet applying a DC-bias magnetic field to the element, a coil exhibiting electrical property corresponding to the magnetic property of the element, and output device for outputting a signal corresponding to the electrical property of the coil. The coil has a specific positional relationship with the element, such that at least part of the magnetic flux generated by the coil passes through the element.

Abstract: The instant invention is a magnetic field sensor intermittently shielded by a controllable, saturable, magnetic shield. The magnetic shield is periodically driven into saturation by means of an excitation coil. The magnetic field to be measured is not disturbed by the shield during those time intervals when the shield is saturated. Intermittent sensing of the magnetic field to be measured, by the intermittently shielded magnetic field sensor, yields a magnetic field measurement unaffected by l/f noise and offset errors.

Abstract: An apparatus for detecting a magnetic field includes a magnetic core, an excitation current source unit, a magnetic flux detecting unit, and a current control source unit. The excitation current source unit includes a first excitation winding disposed around the core, an amplifier having an output coupled to the first excitation winding, and a subtractor for applying to the amplifier a first difference between a voltage corresponding to a supplied excitation current and a voltage corresponding to a current passing through the first excitation winding. The magnetic flux detecting unit includes a second excitation winding disposed around the core, a waveform shaping circuit for shaping the waveform of a voltage induced in the second excitation winding, a pulse generating circuit for outputting pulses in synchronism with the shape waveform voltage, and a sample-and-hold circuit for sampling and holding the voltage corresponding to the supplied excitation current.

Abstract: A fluxgate magnetometer having wide temperature range accuracy, without adding temperature compensating components, is obtained by: (1) a fluxgate adjusted by aligning a permeable magnetic tape core relative to the secondary winding of the fluxgate so as to substantially equalize each of the pulses induced in the secondary winding by the transition from core saturation to unsaturation in both directions, and (2) increasing the fluxgate magnetometer primary drive current above what is normally considered saturation current to reduce sensitivity of the output to temperature and primary drive changes.

Abstract: A direct-coupled fluxgate current sensor which is driven to hard saturation to achieve a sudden change in magnetic properties of the sensor, has: (a) a first closed loop core of ferromagnetic material encased in a sleeve wound with a first toroidal drive winding, the winding for the first core extending around the circumference of the first core; (b) a second closed loop core of ferromagnetic material encased in a sleeve wound with a second toroidal drive winding independent of the first winding, the winding for the second core extending around the circumference of the second core; and, (c) a closed loop core casing which is adapted to cooperate with the first core and the second core, the closed loop core casing and the first and second core being wound as a unit with a toroidal sense winding independent of the first and second toroidal drive windings, the winding for the closed loop core casing extending around the circumference of the closed loop core casing.

Abstract: A terrestrial magnetic sensor has a bobbin body having a magnetic core inserting groove, a silicon gel filled in the magnetic core inserting groove, a magnetic core buried in the silicon gel filled in the magnetic core inserting groove, and a bobbin cover for closing the magnetic core inserting groove of the bobbin body. Thus, this terrestrial magnetic sensor can suppress the decrease in the magnetic permeability by burying a magnetic core in a silicon gel and can be hardly affected by the influences of the variations in an environmental temperature and an external stress.

Abstract: A fluxgate magnetometer includes a body of magnetic material, a drive coil and a sensing coil. At least one of the drive coil and the sensing coil is composed of two portions, each of the two portions being disposed in generally parallel planes which are spaced apart and respectively include an electrically insulating substrate and a spiral shaped portion which is electrically conductive supported by the electrically insulating substrate, the two portions being electrically connected such that electric current flows in the respective spiral shaped portions in opposite rotational senses relative to the body of magnetic material.

Abstract: A device for measuring a weak magnetic field is disclosed. The device includes a substrate, a magnetic core having a high magnetic permeability and in the form of a surface film on a substrate, and at least two coils magnetically coupled to the magnetic core. A pulse generator is connected to one of the coils and is used to drive the magnetic core into intermittent saturation. The other coil is used to generate an output signal. The device can be used for measuring the weak magnetic fields associated with bank notes for identifying the values of the bank notes.

Abstract: A magnetometer having only a single coil winding for sensing the magnetic field along a single axis. Functionally, the invention comprises an oscillator, and means for measuring the duty cycle thereof. The oscillator uses a saturating inductor which also serves as the magnetic-field-sensing element. The inductor is driven with a position voltage and when the current through the inductor exceeds a value which indicates that the core is saturated, the driving voltage switches to an equal-magnitude negative value. This negative drive is maintained until the current again indicates the core to be saturated, at which point the driving voltages switches back to the positive value. With no externally applied field, the inductor current averages to a zero value and the duty cycle of the driving voltage is fifty percent. An externally applied field helps the core saturate in one direction and hinders it in the other, resulting in a change in average inductor current and drive duty cycle.

Abstract: A system for measuring X and Y vector components of a composite magnetic field including static portions such as those produced by the earth's magnetic field, and time varying portions such as those produced by current flowing in a target anomaly to thereby permit determination of the distance and direction from a sensor to the anomaly is disclosed. Highly sensitive fluxgate magnetometers sense total field X and Y axis vector components of the composite magnetic field of interest and produce output signals which are fed through corresponding detector and null circuits to produce total field signals corresponding to the components being measured. These total field component signals are fed through corresponding signal conditioning circuits to equalize the time varying and static field portions of the signal components.

Abstract: A magnetometer sensor is described for a borehole survey. The magnetometer features a bobbin made from a metal alloy such as copper-nickel, which has a very low magnetic permeability, on the order of 1.0001, which can be joined to a magnetic metal alloy, such as Permalloy, by welding, which can be treated by annealing at a temperature of 1500 degrees Fahrenheit and which has a thermal coefficient of expansion generally on the order of the magnetic alloy. In one particular embodiment, the magnetometer sensor comprises a strip of magnetic metal alloy wrapped around the aforesaid bobbin to define a magnetic core, one excitation winding wrapped around the core, a plastic frame for carrying the magnetic core and excitation winding and at least one sense winding wrapped around the frame, the core and the excitation winding.

Abstract: A magnetic detector for detecting the magnetic field of a magnetic field generating substance including an even number of saturable coils aligned in a straight line with the distance between adjacent ones larger than the width of the magnetic field generating substance. The saturable coils are separated into at least two pairs, and a high frequency oscillator is provided to supply a high frequency voltage through a resistor circuit to each pair of the saturable coils. A rectifying voltages circuit is arranged across the resistors in a differential manner as an output. When the magnetic field generating substance is displaced over an interval wider than the width thereof relative to the saturable coils, the magnetic detector generates a linear output voltage.

Abstract: A magnetic sensor including an annular iron core, an annular hollow bobbin for a primary winding which incorporates therein the annular iron core, the bobbin having a plurality of protruded portions which are arranged along a circumference of the annular bobbin with an equal distance, each of the protruded portions being extended in a direction parallel to a center axis of the annular iron core, the primary winding being wound on the annular bobbin at respective portions between adjacent protruded portions with an equal number of turns, a bobbin for a secondary winding having a positioning means for the primary winding in association with the protruded portions of the bobbin for the primary winding when the bobbins for the primary and secondary windings are assembled, the secondary winding being wound on the bobbin to form more than two pairs of winding groups.

Abstract: A direction sensor includes at least one sensor element including a ring-shaped core formed from at least one flexible wire made of zero-magnetostrictive amorphous magnetic material, two pairs of series connected coils spaced from each other at equal intervals about the core for sensing an external magnetic field, with the core being formed by threading the wires through the coils, the coils being excited by an alternating frequency f, wherein voltages of frequency f are produced across each pair of coils; and a process circuit for providing a differential voltage between the voltages of frequency f produced across each pair of coils.

Abstract: A magnetometer (11) for time coded measurement of magnetic fields, which comprises at least one sensor (15) having a magnetizable, rod-shaped core (20) and a winding (19) disposed on the core. To generate an auxiliary alternating field, the winding (19) carries an alternating current, which together with the magnetic field that is to be measured generates in the winding a measurement voltage, the positive and negative half-waves of which deviate from one another as a function of the magnitude of the magnetic field that is to be measured. To attain a simple and accurate evaluation of the measurement voltage, this measurement voltage is applied to the input of the limit-value switch (25), the output (26) of which produces a rectangular voltage, the duty cycle of which directly represents a measure for the magnetic field detected by the core (15) of the sensor.

Abstract: A magnetometer with a time coding is proposed, which serves to measure magnetic fields in the motor vehicle and in particular to measure the direction of the earth field and to determine the driving direction. The magnetometer includes at least one sensor having a horizontally disposed, magnetizable rod-shaped core and a winding disposed on the core. The winding carries an alternating current for generating an auxiliary alternating field, in order to magnetize the core in alternation up to and into saturation. In order to measure the magnetic field detected by the sensor and to generate the auxiliary alternating current, a controlled alternating current source (18) is connected on the one hand to one and the same winding (19), and on the other hand a measurement voltage that can be picked up at this winding (19) is connected to an evaluation circuit (21, 25, 12, 13).

Abstract: Gradient meter to measure the spatial derivatives.DELTA.Hi/.DELTA.j (i=x, y, z ; j=x, y, z)of a magnetic field.This gradient meter comprises two magnetic sonds (7a, 7b) with thin layer, of which the geometric axes of the counterreaction windings are aligned in the direction of axis i, said sonds being spaced from each other along the axis j, the counterreaction current of the first sond being injected in the second sond, the counterreaction current of said second sond being then representative of the value.DELTA.Hi/.DELTA.jto be measured.

Abstract: An electrical drive dircuit for a flux-gate magnetic sensor used in a digital compass for a vehicle provides signals for application to the primary of a flux-gate sensor to assure the core is saturated at a predetermined time during each cycle of the drive signal.

Abstract: A magnetic amplifier employing a single four-legged ferrite core having orthogonally disposed through holes in the core. Biasing is provided of the magnetic core so as to provide operation in the non-linear parts of the core's hysteresis cycle. A first coil on the ferromagnetic core has an AC excitation signal applied thereto and a second coil on the core is wound orthogonally to the first coil and is adapted to have an output signal derived therefrom. A control or input current in a third coil is used to unbalance the magnetic bridge formed by the four legs, so as to produce a mutual inductance different from zero between the first and second coil. The biasing may be provided by a fourth coil or by permanent magnet means.

Abstract: In a zigzag running warning system for automotive vehicles which detects and gives a warning of zigzag running of a vehicle, a terrestrial magnetism sensor generates an electric signal having an amplitude varying in dependence on the direction of travel of the vehicle with respect to the direction of the terrestrial magnetism. An electronic unit in the system discriminates that vehicle is running in a zigzag direction when the amplitude of the electric signals changes in excess of a predetermined value at a period which is less than a predetermined time, and informs the driver of the zigzag running by a speaker, lamp or the like.

Abstract: A flux gate sensor having sense windings for providing an output proportional to the strength of an external magnetic field in which the sensor is placed. A gating circuit which is responsive to a pulse which is generated when the core of the sensor is driven into and out of saturation gates the output of the sense windings to a pair of filters which in turn provide an output proportional to the intensity of the external magnetic field. With two sense windings the outputs of the filters may be used to determine the direction of the magnetic field relative to the sensor and thereby be used as a compass.

Abstract: A system for accurately measuring the direction in which a magnetometer is to be set has a simple construction and is little affected by iron structures on a hull. The system has a magnetometer which includes an excitation source, a magnetic core, an excitation AC winding and an output winding which are both wound around the magnetic core. The output winding is composed of two series connected coils which are wound around the magnetic core and have an equal number of turns. The measuring system applies an alternating current to the core having an amplitude large enough to saturate the magnetic core, and obtains an output from the output winding corresponding to the angle formed between the geomagnetic field direction and an imaginary line obtained by interconnecting the point of connection of the two coils and the central point of the magnetic core.

Abstract: A self-resonant magnetometer using the inductance and interwinding capacitance of a sense winding to establish the frequency of operation. A sense winding signal is amplified to provide a driver current for a driver winding. The driver winding current with the addition of a dc offset current causes the mu (permeability) of a ferrite core to vary in a non-linear region of its B/H curve. The change in the mu of the ferrite core produces a change in flux in the magnetic core if an external magnetic field is present. This change in flux induces a signal in the sense winding.