Abstract: A system for testing the accuracy of an electronic compass is disclosed. The system includes a circular track, a compass seat, an electromagnetic element, a driver, a power source, a calculator, and a magnetic shielding chamber. The electromagnetic element is disposed on the circular track and powered by the power source to generate a magnetic field. The electronic compass is installed on the compass seat and surrounded by the circular track. As such, the electronic compass can measure the magnetic field of the electromagnetic element and calculate direction relative to the electromagnetic element at different points of the circular track when the electromagnetic element is driven by the driver to move along the circular track. The magnetic shielding chamber is for shielding the electromagnetic element and the electronic compass from interference of external magnetic fields.

Abstract: A method for calibrating the attitude of a compass in relation to the platform on which the compass is installed. The compass includes an attitude determining device and an optical sighting device and the compass is integrally mounted on a platform. The method includes the steps of determining the angle between the optical sighting device and the attitude determining device, determining the attitude between the optical sighting device and the platform, and determining the attitude between the attitude determining device and the platform.

Abstract: An improved electronic magnetometer has a flux-concentrating core making grazing contact with a magnetically conductive element which is preferably part of a piezoelectric transducer. The core and transducer are mounted so as to make non-coherent, chattering contact when the transducer is caused to vibrate. A pickup coil attached to a signalling device enables a user to find a null in a field of magnetic flux with novel accuracy.

Abstract: A magnetic sensor mounting assembly embodying the present invention includes a base plate having cradles for pivotally receiving and adjustably locking a sensor supporting platform thereto. The base plate can be attached to an existing rearview mirror mounting member. The assembly further includes a cover providing access for adjusting the platform to a horizontal position and for allowing the rearview mirror mounting stem to extend therethrough.

Abstract: In an azimuth signal generator for an automobile navigation system a change in the rotational rate of an inertia rotary member, which has its rotary shaft held vertically and is driven at substantially a constant speed, is detected as a direction changing rate of the car and the direction changing rate is integrated by an integrator to obtain an azimuth signal. On the other hand, the azimuth of geomagnetism is detected by a geomagnetic azimuth sensor and a correcting signal is produced based on an error between the azimuth signal and the geomagnetic azimuth signal. The correcting signal is negatively feedback to the input side of the integrator, causing the azimuth signal to follow the geomagnetic azimuth signal.

Abstract: Concentrated lines of flux through two loosely mounted magnetically contacting reeds are intermittently mechanically interrupted by breaking the contact infinitesimally, thus deriving a near-maximum generated EMF in a coil surrounding the contact. A piezo transducer driven in feedback arrangement by an oscillator provides an energy-efficient drive for a hammer that irregularly strikes one of the reeds. A compass based on this noncoherent modulation of a flux path is shown and other devices based upon this principle are mentioned.

Abstract: A vehicle orientation detecting device mounted in an automotive or other vehicle cancels an erroneous signal component of a first alternating voltage signal generated as a conductor is rotated so as to intersect a geo-magnetic field. The erroneous component is cancelled by electrically adjusting two phases and magnitudes of a second alternating voltage signal having the same period as the rotating conductor and a 90.degree. phase shifted second alternating voltage. The vehicle orientation is correctly derived from the phase difference between the normal first alternating voltage signal without the erroneous signal component and the second alternating voltage signal.

Abstract: The invention contemplates use of a single magnetic-field (flux) sensor mounted within an elongate probe housing, to continuously generate telemetered electric signals from which the instantaneous orientation of the housing is at all times known and from which changes in orientation may be tracked as a function of probe depth within the borehole in which the probe housing may be displaced. The telemetered electric signals provide accurate and current indications of (a) magnitude of the horizontal component of the earth's magnetic-field lines, (b) direction and magnitude of probe-axis tilt with respect to the gravitational vertical, and the direction of the earth's magnetic field, and (c) a probe-housing frame-angle reference; provision being made within the probe housing for performing substantially all discriminating, detecting and other problem-solving functions, whereby the telemetered signals are directly utilizable by recording and/or display equipment at surface end of the borehole site.

Abstract: Our invention relates to a novel electromechanical method and apparatus for detecting and representing the north direction and/or the heading of an object or vessel in analog and/or digital representation.

Abstract: A phase-sensitive device for determining the direction of a primary magnetic field is disclosed which includes an electrically conductive rotor mounted for rotation about a predetermined axis. The rotor includes means for defining at least one electrical path. The device further comprises means for detecting those secondary magnetic field components induced by rotation of the rotor in the primary magnetic field which are of a frequency equal to the rotation frequency of the rotor and for providing a corresponding first electrical signal responsively to these secondary field components. Means are also provided for detecting the angular position of the rotor with respect to the rotation axis and for providing a second electrical signal corresponding to said angular position of the rotor. The relative phase shift of the first and second electrical signals can then be determined. This relative phase shift is related to the direction of the primary field.

Abstract: A rotation sensor and output signal processing apparatus is presented. The rotation sensor is a ring core flux gate magnetometer whose output varies as a function of the earth's magnetic field. The phase angle of the second harmonic of the magnetometer output is sensed to provide an indication of the state of rotation of the magnetometer. When a state of no rotation is sensed, actuating signals are delivered to a control system to sense borehole parameters and telemeter the parameters to the top of the borehole.