Abstract: A method and receiver system for identifying a location of a magnetic field source using two horizontally displaced tri-axial antennas. In a preferred embodiment two tri-axial antennas are positioned at opposite ends of a receiver frame. Each antenna detects in three dimensions a magnetic field from a source or transmitter. The receiver is maintained in a horizontal plane and the receiver is moved in the horizontal plane until a flux angle measured at each of the two points is zero so that the receiver is in the vertical plane perpendicular to the axis of the source. The depth and location of the source in three dimensions relative to the receiver is determined using the detected field values. The receiver is moved in a direction defined by a line containing the two points of the receiver until a magnitude of the magnetic field detected at each of the two points is substantially the same so that the receiver is positioned above the source.

Abstract: Multi-component induction measurements are made using a resistivity logging tool in an anistropic earth formation. The X-signal (quadrature) is insensitive to borehole eccentricity. A subset of the multi-component measurements are inverted to first determine horizontal resistivities. Using the determined horizontal resistivities and another subset of the multi-component measurements, the vertical resistivities are obtained. Results of using the in-phase signals are comparable to those obtained using multifrequency focusing of quadrature signals.

Abstract: A rotation detecting apparatus capable of increasing the angle detecting precision without being affected by an offset signal resulting from a stress in a silicon chip. The rotation detecting apparatus includes a magnetic sensor array and a magnet rotatable in face-to-face relation with the magnetic sensor array. The magnetic sensor array includes a plurality of groups of sensor elements, each group including four sensor elements. The four sensor elements of each combined sensor element group are so arranged as to be oriented vertically and horizontally in four directions and connected parallel to each other.

Abstract: A method of determining the amount of travel of a rotating component that includes a rotor shaft includes providing a self-contained magnetically-powered encoder. The encoder includes an encoder rotor that extends outward from a sealed housing such that a clearance gap is defined between the rotor and housing. The method also includes rotatably coupling the encoder to the rotor shaft. The method further includes measuring a first position of the encoder rotor and determining a first rotational position measurement of the rotor shaft based on the encoder rotor. The method also includes rotating the rotor shaft to a second rotational position and determining a direction of rotation and a second rotational position measurement of the rotor shaft using the encoder. The method further includes determining a total rotational distance traveled by the rotor shaft between the first rotational position and the second rotational position.

Abstract: Test methods and components are disclosed for testing resistances of magnetoresistance (MR) sensors in read elements. Test components are fabricated on a wafer with a first test lead, a pseudo sensor, and a second test lead. The test leads and MR sensor are fabricated with similar processes as first shields, MR sensors, and second shields of read elements on the wafer. However, the pseudo sensor in the test component is fabricated with lead material (or another material having similar resistance properties) instead of an MR thin-film structure like an MR sensor. Forming the pseudo sensor from lead material causes the resistance of the pseudo sensor to be insignificant compared to the lead resistance. Thus, a resistance measurement of the test component represents the lead resistance of a read element. An accurate resistance measurement of an MR sensor in a read element may then be determined by subtracting the lead resistance.

Abstract: An inductive detector operable to measure relative displacement along a measurement path of a first body including an electrical intermediate device and a second body including at least three windings. At least one winding is a transmit winding and at least one other is a receive winding. The windings are arranged such that relative displacement of the two bodies causes a change in inductive coupling between at least one transmit winding and at least one receive winding. At least two windings are formed by a convoluted conductor with a first portion extending along the measurement path on a first surface of the substrate and a second portion returning back along the measurement path on an opposite second surface of the substrate. The first and second portions are connected via a connection extending between the first and second surfaces.

Abstract: An electronic metal detector having, a transmit coil arranged and adapted to transmit an alternating magnetic field associated with a reactive transmit coil voltage, the transmit coil being connected to transmit electronics arranged and adapted to generate a transmit signal, the transmit electronics having at least two power sources, a first power source and a second power source, wherein the first power source is adapted and arranged to connect to the transmit coil for at least a first period, and the second power source is adapted and arranged to connect to tie transmit coil for at least a second period, the said transmit electronics including at least one servo control negative feedback loop, a first servo control negative feedback loop, which is adapted and arranged to monitor a transmit coil current for at least part of the said first period, and to control at least part of the said transmit signal, the transmit electronics being adapted and arranged to control the transmit signal to produce the reactive

Abstract: A source arrangement for generating electrogmagnetic (EM) wavefields, comprising an EM signal generator, at least three electrodes (141-144) connected to the generator, and a control system. The electrodes are spaced apart but not all in line. The control system is arranged to apply non-coincident time-varying signals or transmissions from the generator between different pairs of the electrodes. The non-coincidence can be by applying the signals sequentially or by applying the signals out of phase.

Abstract: The invention relates to a method for measuring the magnetic permeability of a magnetic material by measuring the magnetic interaction of an electromagnetic field with this material by using a measuring device including a measuring cell connected through a microwave frequency cable (13) to a vector network analyser (12), said method comprising steps for gauging/calibrating said measuring device, for determining corrective coefficients to be applied to the measurements obtained by means of this device, for verifying the non-drift of this device, these steps being carried out with the help of a reference sample, wherein a reference sample is used, comprising at least one inclusion which enables creation, in a given volume, of a local artificial permeability, each inclusion being achieved by combining at least one inductive component possibly associated with a combination of at last one capacitive and/or resistive and/or active component, the frequency response of the electromagnetic properties of each volume be

Abstract: A service tee marker fixture comprises a disk marker and a cylindrical attachment sleeve fastened concentrically to the disk marker and constructed of a flexible material which provides a releasable friction fit with a service tee cap. For certain sleeve materials a stiffener plate is used to secure an end portion of sleeve adjacent to the disk marker. Detents are formed inside the attachment sleeve to grip matching ribs on the cap. An integrally formed inwardly-extending annular flange at an open end of the sleeve helps retain the sleeve on the cap. When installed the wire coil is horizontal and the marker shields the tee, and is further centered over a centerline of the main pipe. A novel method is also disclosed for using the service tee marker fixtures to survey and locate service line end points.

Abstract: A device for generating a magnetic field in a goal area with at least two coils arranged in parallel to a goal area defined and bounded by a goal, wherein a first coil is attached in an area behind the goal and a second coil is attached closer to the goal than the first coil or identical to the goal, wherein the first coil and the second coil respectively have a coil impedance, wherein the coil impedance of the second coil is set so that a magnetic field of the second coil generated due to a magnetic field of the first coil reduces the magnetic field of the first coil at a location within the second coil by at least 20%.

Abstract: A sensor having a signal generation module including a first magnetic sensor, an analog signal processing module, and a signal inversion module for inverting a first waveform and a second waveform, wherein the signal inversion module outputs the first and second waveforms in a first region spanning a first range of angular position of the magnet and outputs the first and second inverted waveforms in a second region spanning a second range of angular position of the magnet.

Abstract: A multimeter includes a case defining an interior cavity in which components of the multimeter are located. The case has a top portion defining a plurality of first button apertures. A rotary selector knob is also provided for selecting a multimeter function. The multimeter further includes a separate front panel juxtaposed to the top portion of the case. The front panel has a plurality of second button apertures in respective register with at least some of the first button apertures. The top portion of the case may define a recess in which the front panel is received.

Abstract: A wireless system for collecting data indicative of a tire's characteristics uses at least one open-circuit electrical conductor in a tire. The conductor is shaped such that it can store electrical and magnetic energy. In the presence of a time-varying magnetic field, the conductor resonates to generate a harmonic response having a frequency, amplitude and bandwidth. A magnetic field response recorder is used to (i) wirelessly transmit the time-varying magnetic field to the conductor, and (ii) wirelessly detect the harmonic response and the frequency, amplitude and bandwidth, associated therewith. The recorder is adapted to be positioned in a location that is fixed with respect to the tire as the tire rotates.

Abstract: An apparatus, method and computer-readable medium for evaluating an earth formation are disclosed. A logging tool which has two coplanar antennas disposed at a known distance from an axis of the logging tool is conveyed into a borehole. The presence of a borehole effect is determined from a difference between outputs of the two antennas. The borehole effect may include eccentering of the logging tool in the borehole. Measurements made by an additional antenna and/or the two coplanar antennas may be corrected for the effects of eccentering. Horizontal and vertical formation resistivity as well as additional petrophysical properties may be determined.

Abstract: A magnetic screening system uses directional gradiometers with high resolution and accuracy to measure magnetic field signatures of target objects (e.g., gun, knife, cell phone, keys) in a volume of interest. The measured signatures can be compared to signatures of known objects stored in a local database. Various mathematical processes may be used to identify or classify target object signatures. A magnetic screening system network according to embodiments of the present invention includes gradiometers, gradiometer processors, screening computers, and a management computer. The gradiometers sense target objects in a subject volume and the gradiometer processors process data obtained from the gradiometers. The screening computers process data output of the gradiometer processors and maintain local databases of signatures associated with known target objects.

Abstract: The present invention provides a method for testing a disc shaped mold structure having a convexo-concave pattern formed on a surface thereof based on a desired design pattern, including at least: transferring a magnetic signal corresponding to a convexo-concave pattern formed on the entire surface of the mold structure to a medium in a direction perpendicular to the surface of the medium, obtaining a reproduction signal by electrically reproducing the magnetic signal from the medium onto which the magnetic signal has been transferred, and comparing the desired design pattern with the reproduction signal.

Abstract: A boring tool is moved through the ground in a region which includes at least one electrically conductive in-ground line and which is subject to static magnetic fields including the magnetic field of the earth.

Abstract: Discriminating between a cable locating signal and a false cable locating signal is described. A reference signal, which contains a locating signal frequency impressed on it, is transmitted in a way which provides for detection of a phase shift between the locating signal and the false locating signal. Based on the phase shift, a receiver is used to distinguish the locating signal from the false locating signal.

Abstract: To provide a rotation angle detecting device, in which undesirable noises from an angle calculating circuit can be reduced to increase a detection accuracy, outputs of four linear magnetic sensor arrays arranged on a non-rotatable member confronting a magnetic generating element and arranged in a plane perpendicular to the axis of rotation, the sensor arrays being arranged along four sides of an imaginary rectangular shape, are read out by signal read-out circuits, and then converted into digital signals by AD converting circuits in order to calculate an angle of rotation of the magnetic generating element by an angle calculating circuit. The signal read-out circuits and the AD converter circuits are arranged outside of the magnetic sensor arrays arranged in a generally rectangular pattern, and the angle calculating circuit is arranged inside of the magnetic sensor arrays, all being mounted on a semiconductor chip.