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: An apparatus and method for detecting anomalies in ferrous pipe structures is presented. A sensor having one or more sensor shoe members is placed in the interior of a ferrous pipe structure to be inspected. Each sensor shoe member has one or more magnetic field generating apparatus, with a three-axis fluxgate magnetometer for detecting magnetic fields in the region of the ferrous pipe structure adjacent to which the sensor shoe member is placed. Any magnetic fields in the pipe structure, whether imposed externally, or remnant, which are detected, are sensed and resolved into components in three mutually orthogonal directions for enhanced accuracy.

Abstract: An apparatus and method for detecting anomalies in ferrous pipe structures is presented. An electrical current is passed through the ferrous pipe structure so as to create a magnetic field in the pipe. A sensor having one or more sensor shoe members is placed in the interior of a ferrous pipe structure to be inspected. Each sensor shoe member has one or more magnetometer elements for detecting the magnetic fields in the region of the ferrous pipe structure adjacent to which the sensor shoe member is placed.

Abstract: An improved fluxgate instrument for measuring heading as well and pitch and roll angles is disclosed. A plurality of fluxgate sensors are continuously energized with a DC feedback signal derived from the reading of each sensor so as to minimize magnetic cross-coupling between the sensors. In addition while two sensors are gimbally mounted to sense the horizontal components of the earth's magnetic field, the vertical field is sensed by two sensors strapped down relative to the instrument casing for sensing the earth's vertical magnetic field in order to compensate for latitude. Finally, sine and cosine coils surround the gimbally mounted sensors and generate AC fields which are sensed by the gimbally mounted sensors and are used to calculate the pitch and roll angles.

Abstract: An inductively coupled electronic lock system wherein the key has a clock driven variable pulse width generator with alterable pulse sequence input to an inductor. The lock part of the system has an inductive pick-up which discriminates against all but a preselected sequence of pulses, converts the received signals to DC and powers a motor to open the lock.