Abstract: A solid state compass having a pair of flux gates orthogonally disposed on a gimballed platform and coupled by a single pair of conductors to an electronic subsystem which includes a current source for energizing the respective flux gates and a detection and control circuit to provide control of flux gate energization and to detect signals derived from each flux gate and from which compass heading is derived.

Abstract: In order to measure a magnetic field, an exciting current rising in small increments is applied to a measuring probe so that the coil of the probe traverses the entire range from the negative saturation up to the positive saturation. At the secondary side, respective voltage pulses which decay according to an e-function are measured at the coil. The time constant of the voltage pulses corresponds to the respective coil inductance. Since the coil inductance is shifted relative to the zero point of the exciting current due to an external magnitude field, more voltage pulses with a high time constant are produced on one side of the zero point than on the other side. By means of digital counting of all voltage pulses whose time constant exceeds a minimum value both given a negative exciting voltage as well as given a positive exciting voltage, one obtains two measured values whose difference directly produces a measured value for a strength of the external magnetic field.

Abstract: A heading detecting apparatus is attached to a moving object and includes a geomagnetic field sensor for detecting the direction of the earth's magnetic field in terms of orthogonal first and second signals and a computing circuit responsive to orthogonal first and second electric signals from the geomagnetic field sensor. In the computing circuit, when any one of the orthogonal first and second electric signals from the geomagnetic field sensor is a predetermined value, the value of the other electric signal is detected so that in accordance with the detected value an offset value is computed and stored, and the electric signals from the geomagnetic field sensor is corrected in accordance with the offset values.

Abstract: A magnetic field measuring apparatus including a magnetic sensor having an excitation winding and orthogonal first and second output windings for generating a first and a second output signal indicative of the orthogonal components of an external magnetic field, adjusting circuits for adjusting the amplitude and frequency of the sensor output signals, circuits responsive to common timing signals whereby the outputs of the adjusting circuit are subjected to sample-and-hold operation and A/D conversion and the resulting converted outputs are counted to generate count outputs, and a first and a second display unit for simultaneously displaying the count outputs.

Abstract: A vehicle's heading indicating apparatus includes a direction-finding sensor having a pair of external field sensing windings wound perpendicular to each other, a sensor exciting oscillator circuit, a signal sampling timing circuit, sample-and-hold circuits, comparators, a logic circuit and an indicator circuit. The output of each of the sensor windings is divided into predetermined (N+1) signal levels such that the heading or direction of travel of a vehicle is detected and indicated in accordance with the combination of each two signal levels sensing the heading, and also large disturbance of the earth's magnetic field is sensed such that the just preceding direction of travel obtained is indicated when the earth's magnetic field is excessively low or high.

Abstract: A suspension system suitable for a flux gate compass having compass windings (14) includes a ball joint (4,5,6) which permits both tilt and twist about a vertical axis, and a separate alignment element (16) for causing the windings to follow twisting motion of the fixed structure. The alignment element takes the form of a flexible printed circuit made into a double spiral form and carrying electrical conductors to provide the electrical connections to the windings. A zig-zag shape may be used instead of a spiral. The suspension does not suffer from the geometric imperfections of a Hooke's joint and avoids the need for separate flexible conductors which can interfere with the suspension operation and can break.

Abstract: A three axis orientation sensor for sensing the orientation of an attached object such as an aircraft with respect to the earth's magnetic field. The sensor can be aligned and used in the presence of ferrous materials and magnetic fields which are inherent in the surrounding environment of the aircraft.

Abstract: Disclosed is a magnetic course detector capable of accurately detecting the bearing of the course of a traveling body independently of the position a magnetic bearing sensor is installed in the traveling body through rotatably mounting the magnetic bearing sensor and making corrections for the offset and sensitivity of its output.

Abstract: A gradiometer for measuring magnetic field gradients. The gradiometer is formed by a number of magnetic field sensing devices. Each device has its own axis of sensitivity and produces a signal proportional to the magnetic field strength in the direction of its axis of sensitivity. The devices are mounted so that the different axes of sensitivity are at different angles to each other and so that at least some of the devices are displaced from each other along a common axis. The signals from the devices are combined so as to balance out unwanted components, particularly those due to the earth's magnetic field.

Abstract: A direction detection apparatus comprising a magnetic sensor which senses a geomagnetic azimuth, a turning-angle sensor which senses a turning angle dynamically, a magnetic-disturbance detector which detects a magnetic disturbance on the basis of the output of the magnetic sensor, and a signal switching device which transmits either the magnetic sensor output or the turning-angle sensor output to a display device in accordance with a signal from the magnetic-disturbance detector. The traveling direction of a moving object can be detected as a precise geographic azimuth even when the moving object lies in a place subject to the magnetic disturbance.

Abstract: The present invention incorporates a flux-gate sensor for a vehicle compass. The sensor is mounted in association with the mounting system for a rearview mirror mounted to the vehicle windshield. In one embodiment of the present invention, the flux-gate sensor is contained in the mounting bracket for the rearview mirror. This location isolates the sensor from the undesired effects of the metallic mass of the vehicle as well as the dashboard, typically housing the vehicle's wiring.

Abstract: A magnetic field detecting system for use with a flux-gate sensor includes an oscillator, the output of which is applied to a digital bandpass filter and frequency divided and also applied to the sensor, and phase detectors such that the frequency and phase of the output signals from the flux-gate sensor have a predetermined relationship to the excitation signal. In one embodiment of the invention, the direction indicating output signals from the phase detectors are applied to a suitable interface circuit for a microprocessor which converts the signals to a digital format employed for application, to an alpha-type display for displaying the octal magnetic orientation of a vehicle.

Abstract: Devices for vectorially summing two signals. In a first embodiment (FIG. 3) the vectorial summation is implemented by a mechanical sin/cos mechanism in which a crank 22 drives two linear potentiometers 27 and 29, 90.degree. out of phase. In a second embodiment (FIG. 6) a polarized light resolver generates the sin and cos functions. In a third embodiment (FIG. 8) a printed circuit resolver generates the sin and cos functions.

Abstract: An azimuth determinating apparatus wherein the azimuth sensor is oriented to a specified direction, and the deviation of the two-component detection signals of the azimuth sensor from the pointing direction of the azimuth sensor are corrected by the adjustment of the two-component detection signals with the adjusting circuit in accordance with the indication on the amount of deviation indicated by the indicating circuit, whereby distortion of the output signals due to the residual magnetism of the azimuth sensor is corrected and the true azimuth can be determined.

Abstract: A digital compass including a two-axis earth's magnetic field sensor and a earing processor computes the bearing for local display or transmission from a remote site to a local site for display and/or storage. The bearing processor portion of the digital compass includes an analog-to-digital converter configured for ratiometric measurements to compute the ratio of the x-axis and y-axis signals (smaller divided by the larger) from the aforementioned two-axis earth's magnetic field sensor. A programmable memory unit controlled, inter alia, by the data line outputs of the analog-to-digital converter, contains the arc tangent function for angles from 0.degree. to 90.degree.. The data line outputs from the memory unit defines a quadrant displacement angle in the range of 0.degree. to 90.degree. which is subsequently added to the cardinal point forming the lower boundary in bearing of the host quadrant.

Abstract: In a direction indicator including a direction sensor having an excitation coil wound on a core and two output coils wound thereon to cross at the right angles with each other, a direct current of given amount is supplied to the two output coils and a direct current magnetic field is produced so that the maximum values of the output signals is made equal by adjusting the gain of the output signals.

Abstract: A magnetic sensor is disclosed which features an arrangement that relies upon the principle of a fixed, non-pendulous magnetic sensing device (2), which is rendered insensitive to the effect of the earth's vertical magnetic field component by means of an adjacent cooperating magnetic member (20) pendulously-supported to maintain its axis along the true vertical. Means (34, 44, 46, 48, 50) are disclosed whereby the magnetic field provided by the pendulously-supported magnetic member is automatically adjusted to cancel the earth's vertical field even when the latter changes for any reason.

Abstract: A direction finding system of the type finding a present direction on 4N direction divisions defined by 2N boundary levels for automotive vehicles, said system comprising a magnetic sensor circuit for generating a pair of electric signals indicating two perpendicular components of the earth's magnetic field, a logic circuit for signal-converting the electric signals, discriminating and latching to generate direction indicating 2N binary signals with reference to predetermined 2N boundary indicating levels, a sorting circuit for sorting the binary signals to generate one of 4N direction signals and a display device for displaying a corresponding direction.

Abstract: The magnetic field strengths in two perpendicularly oriented ferromagnetic core members are converted to voltages and summed to form a composite field strength voltage. The core members are mounted in a vehicle and the slope polarity and amplitude of the composite field strength voltage are used to determine the heading of the vehicle.

Abstract: In a magnetic compass compensation system suitable for use within a ferrous land vehicle, a secondary magnetic sensor senses, the total magnetic field as components along a three axis system drawn vertical, lateral and transverse to the ferrous vehicle. Compensation signals corresponding to the permanent and induced magnetic fields of the vehicle are isolated from the total magnetic field. The compensation signals are applied to compensation coils surrounding a primary magnetic sensor for providing an output equivalent to the horizontal components of the earth's undisturbed magnetic field.

Abstract: Apparatus for determining the positional coordinates of a moving object including a plurality of magnetic field vector detecting devices, an inclination detecting device for detecting inclination of the magnetic field vector detecting devices, a distance detecting device for detecting the distance that the moving object has travelled, and arithmetic means which receives outputs from the magnetic field vector detecting devices as well as from the inclination detecting device, calculates the horizontal component force vector of the geomagnetic field by using the outputs from the magnetic field vector detecting devices and from the inclination detecting device, further calculates the vector in the progress direction of the moving object by referring to the horizontal component force vector, and integrates the product of the vector in the progress direction and the output from the distance detecting device, whereby the positional coordinates are obtained as the output of the arithmetic means, and the coordinates

Abstract: The drive signal applied to the drive winding of a magnetometer is provided by a voltage controlled oscillator. The average current flowing through the drive winding is monitored, and a signal representative of the average current is applied to the input of the voltage control oscillator. The sense windings of the magnetometer are connected to a servo-loop which causes a current to flow in the sense windings which produces a magnetic field cancelling the sensed components of the earth's magnetic field. The magnetometer uses a drive signal which saturates the core for only a short duration of time thereby reducing the power required by the magnetometer while ensuring complete saturation of the core.

Abstract: A system for detecting magnetic field direction comprising a pair of orthogonally positioned rods each having a rectangular shaped BH curve, a switching winding, and detectors for detecting the switching of magnetic polarity of each rod to either of its remanent states. A switching current having a triangularly shaped waveform is supplied through said switching windings to drive said rods between their remanent states at times depending upon their angular relationship with the external magnetic field. Counters record the difference in time, measured from the immediately preceding zero current crossover points between the switching of each rod first to one of its remanent states and then to the other of said states. The time difference in one rod is proportional to the sine of the angle between the external field and said one rod and to the cosine of the angle between the external field and the other said other rod.

Abstract: An improved earth's magnetic field sensing compass utilizes a flat, toroidal flux valve in which pickoffs sense mutually perpendicular components of the magnetic field and the fields are nulled by the closed loop feed back of nulling currents into respective pairs of the sensor pickoffs.

Abstract: A compass device for underwater use and having substantially no magnetic nature or influence utilizes three Hall effect generators in an array wherein two of the generators have their principal axes of magnetic response extending normal to one another and at 45.degree. to the axis of the third generator. The array is rotatable relative to a base carrying three lights and solid state analog logic circuitry for causing the lights to be variously lighted and extinguished to indicate a need to turn left, to turn right, or being on course.

Abstract: Set out herein is an electronic compass suitable for public use having a conventional pin supported magnetic needle which is placed over a set of magneto diodes or Hall devices arranged in quadrature. The magneto diodes or Hall devices are thus exposed to the highly enhanced magnetic field around the needle and will thus provide a direct readout, in electrical form, of the deviation from magnetic North. In this manner a relatively conventional arrangement of a magnetic needle may be utilized to provide the necessary signal source for electronic pick-off with the same accuracy obtained by a conventionally suspended arrangement practiced in the past.

Abstract: A detector to detect angular positions of a rotatable magnet, i.e., a magnetic compass, having one or more flux-sensitive components, namely Hall-elements. The detector includes a substantially flat and circular carrying body to be mounted on the top or bottom of a compass. On the carrying body the Hall-elements are mounted parallel to and close to the flat surface and positioned on diameters perpendicular to axes of symmetry of the flat surface. The carrying body can be rotatably fastened on the compass case and locked in desired predetermined positions.

Abstract: A gyroscopic device of the type having a short-circuited rotor winding or conductor so shaped so as to produce axial and radial flux components when rotated in the earth's magnetic field is coupled to a coaxial sensing coil coaxial which gyroscopically stabilized thereby, signals induced in the sensing coil due to the axial flux component of the rotor is used to derive magnetic heading information and there is provided at least one further coil on the supporting body and inductively linked to the sensing coil and rotor such that when the sensing coil is gyroscopically stabilized by the rotor, the coil supported on the supporting body in relation to the gyroscopically stabilized sensing coil is such that any changes in angular orientation of the supporting body relative to the gyroscopically stabilized sensing coil introduces changes in the signal voltages induced in the coils.

Abstract: A solid state compass system for use with automobiles or the like. The system consists of a dashboard mounted readout unit which receives signals provided thereto from a remotely located solid state magnetic bearing sensor, the latter being responsive to the earth's magnetic field. The solid state magnetic bearing sensor described herein, includes a pair of Hall effect semiconductors and ancillary electronic circuits. Two ancillary circuit types are described. One circuit is designed to output digital codes indicative of magnetic heading; the other circuit is designed to output two currents which are indicative of sine and cosine components of magnetic heading. The circuit designed to output digital codes includes sinusoidal waveform generators, a binary counter, a differential comparator amplifier and digital latch and decoding circuits. The circuit designed to output currents indicative of sine and cosine components of magnetic heading are comprised of a pair of linear differential buffer amplifiers.

Abstract: An inclination responsive device including a coil energized to produce a magnetic field extending along a normally vertical axis of the device, and a flux gate assembly adapted to respond to a horizontal component of that field upon tilting movement of the axis to an inclined non-vertical position, and to thereby produce an output which varies in response to changes in inclination. The flux gate assembly is desirably also responsive to the earth's magnetic field or another ambient field to also produce an output representing directional orientation of the device with respect to the ambient field.

Abstract: A flux gate unit for producing an output representing the directional orientation of the unit with respect to the horizontal component of the earth's magnetic field, and in which a saturable flux gate magnetic core structure is mounted for leveling movement relative to associated flux gate coil means, in a manner enabling maintenance of the core structure substantially continuously in level condition while avoiding the necessity for leveling movement of the flux gate coils, and thereby avoiding the necessity for connection of electrical leads to a movable part.

Abstract: A magnetic compass in which the compass magnet is an electromagnet energized only when in a horizontal disposition to provide a correct heading indication without error due to tilting of the compass magnet.

Abstract: A direction finding device employs a magnetic field sensor utilizing a vibrating magnetic reed switch with adjustable magnetic bias to vary the sensitivity or dead band. By sensing magnetic North, it indicates audibly, visually or by nerve stimulus any departure from a preset course. When attached to a moving object or person it serves as a warning or guidance system.

Abstract: An orientation system adapted to be mounted within a vehicle, comprising a display including a rotational heading indicating compass card fabricated from an image retaining electronic display panel responsive to bearing data signals.

Abstract: A navigational device for use by underwater swimmers and divers in which a telescopically extensible boom is releasably and pivotally attached to the swimmer or diver. A compass device such as a magnetometer or fluxgate sensor is mounted at the end of the boom and is connected to an audio signal generator so that signals are generated if the swimmer deviates to either side of a predetermined course. The swimmer or diver wears a bone conduction transducer on each side of his head, which are connected to the audio signal generator via a gating device so that he can receive an audio signal, presented selectively on either side of his head, which is indicative of deviation from his predetermined course.

Abstract: A solid state magnetic sensor system for indicating the direction of an applied magnetic field and more specifically as a compass system for use with automobiles or the like. The system consists of a dashboard mounted readout unit which receives signals provided thereto from a remotely located solid state magnetic bearing sensor, the latter being responsive to the earth's magnetic field. The solid state magnetic bearing sensor described herein, includes a pair of Hall effect semiconductors and ancillary electronic circuits. Two ancillary circuit types are described. One circuit is designed to output digital codes indicative of magnetic heading; the other circuit is designed to output two currents which are indicative of sine and cosine components of magnetic heading. The circuit designed to output digital codes includes sinusoidal waveform generators, a binary counter, a differential comparator amplifier and digital latch and decoding circuits.

Abstract: A magnetism detecting system, in which reference magnetic fields sequentially scan many radial scanning lines obtained by dividing a plane to be detected at regular intervals of a desired angle with respect to an origin positioned at the common intersecting point of said scanning lines. At least one parametrically excited second harmonic oscillator detects the direction and magnitude of a magnetic field to be detected along each of the scanning lines. A display device is provided for scanning and displaying the plane with respect to the origin in synchronism with the scanning of each of the scanning lines. A detected output is applied to the display device when the magnetic field to be detected and the reference magnetic field coincides with each other in direction and in magnitude.

Abstract: An apparatus is disclosed for determining a measured direction such as the direction of a ship or airplane relative to an external magnetic field such as the magnetic field of the earth. This apparatus comprises means for establishing a magnetic field rotating at constant angular velocity, located to influence the external magnetic field. The rotating magnetic field vector bears a known angular relationship as a function of time to the measured direction. A detector is located to be influenced by the rotating and external fields for detecting the occurrence of a predetermined angular relationship between the rotating and external magnetic field vectors.

Abstract: A timing circuit receives substantially square wave clock signals and generates Sine and Cosine driving signals therefrom at a predetermined frequency for application to first and second mutually perpendicular Hall effect generators. The output signals from the Hall effect generators are algebraically summed to provide a heading signal, the phase displacement of which with respect to the driving signals, is representative of the orientation angle between one of the Hall effect generators and magnetic north. A counter is synchronized to begin to count clock pulses at the beginning of each period of the driving signals. A logic circuit is effective to disable the counter when the count therein is representative of the orientation angle. The count is stored in a memory and displayed on a readout device which is, in turn, updated at the end of each period of the driving signals' frequency.

Abstract: A flux valve compass heading repeater system is provided with a compensating system which, when connected to a three-legged flux valve, provides fully compensated, three-wire output signals of the synchro data transmitter type for direct use in apparatus requiring precision three-wire heading data. The compensating system includes control circuits for generating sine and cosine components of magnetic heading and for compensating them for typical compass errors such as those induced by changes in operating latitude and two cycle and index errors. Latitude compensation is accomplished by a novel proportional automatic gain control; two cycle cardinal heading error compensation is accomplished by a compensation circuit having only a single manual control, while index error compensation is similarly accomplished by a compensation circuit requiring only a single manual control.

Abstract: A thin film compass apparatus utilizing a plurality of thin film magnetometers arranged in an orthogornal coordinate system to provide an earth reference compass having total tilt immunity.

Abstract: A flux valve compass heading repeater system is provided with a compensating system which, when connected to a three-legged flux valve, provides fully compensated, three-wire output signals of the synchro data transmitter type for direct use in apparatus requiring precision three-wire heading data. The compensating system includes control circuits for generating sine and cosine components of magnetic heading and for compensating them for typical compass errors such as those induced by changes in operating latitude and two cycle and index errors. Latitude compensation is accomplished by a novel proportional automatic gain control; two cycle cardinal heading error compensation is accomplished by a compensation circuit having only a single manual control, while index error compensation is similarly accomplished by a compensation circuit requiring only a single manual control.

Abstract: A flux valve compass heading repeater system is provided with a compensating system which, when connected to a three-legged flux valve, provides fully compensated, three-wire output signals of the synchro data transmitter type for direct use in apparatus requiring precision three-wire heading data. The compensating system includes control circuits for generating sine and cosine components of magnetic heading and for compensating them for typical compass errors such as those induced by changes in operating latitude and two cycle and index errors. Latitude compensation is accomplished by a novel proportional automatic gain control; two cycle cardinal heading error compensation is accomplished by a compensation circuit having only a single manual control, while index error compensation is similarly accomplished by a compensation circuit requiring only a single manual control.

Abstract: A static non-swinging device for determining the course on board a vehicle comprising a magnetometer having three axes for determining the components of the earth's magnetic field along three axes connected to the vehicle, a vertical gyroscope and a computer for calculating the direction with respect to the vehicle of the horizontal component of the earth's magnetic field, wherein said magnetometer comprises on each axis a single coil having a saturable core controlled in such manner as to furnish a d-c voltage which is proportional to the component of the magnetic field along said axis.