Abstract: An electronic compass has a compass housing. An electronic magnetic field sensor is disposed in a fixed position relative to the compass housing. A magnet is rotatably mounted relative to the magnetic field sensor and independently aligned with a terrestrial magnetic field. The magnet has a magnetic field with a magnetic field direction and the electronic magnetic field sensor is located within a range of influence of the magnetic field. The electronic magnetic field sensor has a first magnetoresistor with a first fixed reference axis and an electric resistance of the first magnetoresistor is a function of a first angle of rotation between the fixed first reference axis and the direction of the magnetic field. The electronic magnetic field sensor defines a first differential bridge circuit and the first magnetoresistor is disposed in the first differential bridge circuit which during operation of the compass, supplies an output voltage dependent on the first angle of rotation.

Abstract: An apparatus for mounting a magnetometer including a frame and a platform mounted for rotation within the frame. The magnetometer and one or more counterweights are mounted within the platform such that gravity acting on the counterweights maintains the magnetometer in a horizontal orientation. A first coil is coupled in parallel with the magnetometer and is wound around the perimeter of the platform. A second coil is wound around the perimeter of the frame such that the first and second coils form an air core transformer. The second coil terminates in two terminals which provide a communication port. A sensing circuit coupled to the port electrically communicates with the magnetometer via the inductive coupling provided by the transformer. In alternative embodiments, each of the first and second coils is implemented as two coils with associated diodes.

Abstract: Continuous vectorial magnetometer having a magnetostrictive pickup including a capacitive pickup which contains a capacitor at least one of whose electrodes is constituted of a material having magnetostrictive properties, and means for measuring the variation of the capacity of the said capacitive pickup under the action of an external magnetic field. The invention also relates to a gradiometer entailing the application of two capacitive pickups of the kind used in a magnetometer. The magnetometer is applied to the measurement of continuous or slowly varying magnetic fields, and the gradiometer to the measurement of a magnetic field gradient.

Abstract: The invention relates to a navigational instrument for automatically controlling the stability of a mobile target, or locating the position of the target with respect to one of several reference planes. The arrangement includes a moving part A whose base G is weighted so that the moving part takes the form of an anchor which pivots about an axis B located on a fixed part fastened to or defined by the moving target. The base G of the moving part has two arms. In an AC embodiment of the invention, the arms are provided with electrically conductive windings and the fixed part includes two electrically conductive windings energized by alternating current. If the fixed part is tilted, one of the windings in the moving part will penetrate the fixed winding to a depth proportional to the tilt angle. At this point, an alternating current, proportional to the tilt angle, will be induced in the winding in the moving part.

Abstract: A quick ranging technique controlled by a microcomputer, makes predetermined stepped adjustments to the charge times in a ranging circuit to bring the charge time into a required range, thusly minimizing calibration time for an electronic compass; a digital filter also controlled by the microcomputer smooths out the magnetic field component signals.

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: An aircraft heading correction system utilizing the horizontal field strength of the earth's magnetic field to determine the tangent of the dip angle generally associated with a given field strength. The tangent of the dip angle is then used to generate a signal which corrects the flux valve heading during accelerated flight.

Abstract: Multiplexing a bandpass filter circuit to work with a flux-gate sensor output to minimize the amount of electronic circuitry required to work with the control system and to reduce the effect of gain on the circuit by emphasizing repeatability.

Abstract: A remote indication compass, a sensor of which is formed by a magnetic compass (1) and magnetoresistive sensors (2) attached thereto, by means of which sensors the field created by the magnetic compass is measured. The signal of the sensors is analogous as well as cyclic with respect to the angle between the fastening plate of the sensors and the northern direction indicated by the magnetic compass, the length of a cycle being 360.degree.. The angle between the sensors is selected in such a manner that the flat areas of the signals do not coincide.The sensor signals are amplified and digitalized and scaled. The determination of direction is carried out by comparing the sensor readings to tabulated sensor readings corresponding to different directions or alternatively by comparing the ratio of the sensor readings to the ratios of the tabulated sensor readings. The direction data so obtained is further corrected by means of a deviation correction table created in the operating condition and stored in a memory.

Abstract: A technique is provided to combine software and hardware; the hardware being used to place voltage levels into narrow ranges and the software being used to perform the precise calibration.

Abstract: A magnetic direction sensor having a head constituted by a magnetic wound core composed of a ferromagnetic metal ribbon; a winding for exciting the magnetic wound core; a first output winding wound around the core such that it encircles two opposite portions of the core and a second output winding wound around the core at a certain angle with the first output winding such that it encircles two other opposite portions of the core; the first and second output windings providing output signals for determining the direction of the external magnetic field with respect to the head, and the inner and outer ends of the ribbon overlapping each other circumferentially by a certain angle .theta. may be between 0.5 and .theta..sub.max satisfying the equation: .theta..sub.max =1/4D+1.5.alpha.+1 wherein D represents the outer diameter of the core and .theta. represents a desired direction accuracy. This structure of the sensor head enables it to obtain a high direction accuracy.

Abstract: A drive circuit applies an oscillating signal to the drive coil of the fluxgate thereby generating output pulses from the detection coils of the fluxgate, which pulses have an area proportional to the magnetic flux through that coil. The output pulses are integrated sequentially by an integrator. The output may be used directly to obtain the orientation of the fluxgate, and hence of a vessel in which the fluxgate is mounted but it is preferable on the grounds of accuracy and speed of response to apply a predetermined number of pulses from each detection coil, apply a constant signal to the integrator and measure the times between the application of that constant signal and the integrator output attaining a predetermined value. This may be measured digitally giving a more accurate measurement of the fluxgate orientation. Suitable error elimination means may be provided.

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: An inclinometer has a ferromagnetic ball levitated between pairs of electromagnets. When the inclinometer changes attitude, the ball moves in response to the change in relative gravity direction. Alternating currents are applied to the proper electromagnets and in the magnitudes needed to re-center the ball. The same signals which determine the re-centering currents are the inclinometer outputs.

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: 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: The peaks of synchro or step data representative of compass heading are detected and the resulting logic levels are latched into a register by an enable pulse generated in response to the data itself. Three outputs from the register are fed directly to the computer input port and provide 1/6.degree. resolution and 1.degree. range. Two of the register outputs are decoded and used to operate an up/down counter. The output of the counter is applied to the computer input port and provide 1.degree. resolution and 16.degree. range.

Abstract: An apparatus for sensing the orientation of an inclinometer in both direction and magnitude for determining the velocity and direction of currents in a body of water having a magnetic north seeking sphere buoyantly supported in a housing. Implanted on the sphere is a plurality of tuned circuits of different resonant frequencies set at right angles to each other and a sense-drive winding or coil mounted about the housing. Upon applying a series of pulses of voltage to the sense-drive coil, the tuned circuits will oscillate with decaying amplitude at their resonant frequencies in the intervals between the pulses of voltage. The mean voltage across each of the tuned circuits is a measure of the amount and direction of tilt of the housing caused by the currents. The sense-drive coil senses these voltages across the tuned circuits and between the induced pulses of voltages, will transmit them to conventional recording equipment whereby a continuous determination of the currents velocity and direction are obtained.