Abstract: A high-resolution magnetic encoder system includes a magnetic resistive sensor, a fixed suspension, and a mechanism. The magnetic resistive sensor is mounted to the fixed suspension above a magnetic medium having at least one magnetic track. The fixed suspension is attached to the mechanism, such as a housing, a substrate, and/or an electronic board. The sensor is adapted to perform a relative movement with respect to and in close contact to the surface of the magnetic medium. The magnetic medium may be protected by an overcoat layer. The magnetic resistive sensor may be Giant Magnetic-Resistive (GMR) sensor and/or a Tunneling Magnetic-Resistive Sensor (TMR).

Abstract: The present invention relates to methods for determining the existence and location of parasitic stress-inducing forces on a substantially cylindrical rod portion defined along a first axis and when this rod is made of a magnetostrictive material. The method according to the invention is essentially characterized in that it consists in magnetizing the wall of the rod portion in a pseudo-helix 10 centered on the first axis, in applying a forced stress between the two ends of the rod portion, in measuring, along the rod portion, the magnitude of the magnetic field created by the rod portion after it has been subjected to the forced stress, these measurements being taken in a direction substantially parallel to the first axis, and from these measurements, in deducing the existence and location of the parasitic stress-inducing forces on the rod portion. The invention also relates to a device for implementing this method.

Abstract: A magnetic anomaly detector includes a magnetically active device which produces analog signals in response to magnetic fields. The analog signals are time quantized and then discrete-time differentiated. The differentiated signals are applied to a low-pass filter. The filtered signals are Fourier transformed into an amplitude-frequency spectrum. An error detector compares at least one reference amplitude-frequency spectrum with the reference spectrum to identify the presence or absence of a magnetic anomaly. The resulting error is displayed on a monitor or operates an alarm.

Abstract: A magnetic field sensor device includes at least two magneto-resistive sensor elements and one switch which is connected to the at least two magneto-resistive sensor elements, and makes at least one magneto-resistive sensor element of the at least two magneto-resistive sensor elements electrically connectable into a magnetic field detection arrangement.

Abstract: A method of manufacturing a sensor module includes providing a substrate comprising a magnetically sensitive sensor element. The sensor element and the substrate are encapsulated with at least one mold material that is configured to apply a bias magnetic field to the sensor element.

Abstract: A magnetoresistive sensor system includes a plurality of chip carriers, such that each integrated circuit among the plurality of chip carriers is associated with a respective magnetoresistive sensing components. A plurality of magnetoresistive sensing components can be arranged in a rotary array, wherein each magnetoresistive component among the plurality of magnetoresistive components is associated with a respective integrated circuit among the plurality of chip carriers and wherein the plurality of magnetoresistive sensing components comprises sensing components that are spaced irregular from one another in order to optimize the performance of the rotary array and meet requirements of a particular magnetoresistive sensing application.

Abstract: A high-Q human-portable, battery-powered self-correcting tunable resonator in a transmitter apparatus for inducing alternating currents of high quality in buried conductors to facilitate their location. The transmitter apparatus employs an FET-driven capacitive tuning circuit and a coil design that achieves high precision, high-quality transmission signals, and which is equipped with a high-voltage booster for facilitating fault-localization applications.

Abstract: Transient measurements made at two spaced apart receivers responsive to separate activation of two transmitters symmetrically disposed about the two receivers. The transmitters and receivers are on an instrument having a conductive body induces currents in the earth formation. The effect of the conductive body is removed by using deconvolving the signal at one receiver using the measured signal at the other receiver. The symmetric transmitter configuration also enables compensation for receiver differences.

Abstract: A method for making directional resistivity measurements includes sequentially transmitting first and second axial and transverse electromagnetic waves in a borehole and receiving substantially pure axial and transverse components of each of the transmitted waves. A composite ratio of the received components is computed and may be utilized as an indicator of various formation parameters. The invention advantageously provides for the acquisition of compensated directional resistivity measurements.

Abstract: In one aspect an induction resistivity tool incorporated into a downhole tool string comprises an outer wall of a downhole component comprising an outer diameter and at least one induction transmitter assembly disposed along the outer diameter. The at least one transmitter assembly comprises at least one induction transmitter coil wound about at least one core. The at least one transmitter coil is adapted to project an induction signal outward from the outer wall when the at least one transmitter coil is carrying an electrical current. The transmitter assembly is adapted to create electromagnetic fields that originate the induction signal from outside the outer wall and substantially prevent the signal from entering the outer wall.

Abstract: The object is to produce a magnetic encoder having a large outer diameter at a low cost, provide a sensor case which is compact in size and can be easily mounted and dismounted with a sensor element received therein, and to provide a double row rolling bearing with a preload application device and a rotational speed sensor which comprises a small number of parts and thus can be assembled easily. A magnetic member 12 of the magnetic encoder 11 is made of a magnetic material bound by rubber. The magnetic member 12 is bonded to an annular presser member 8, which also serves as a metal core, by an adhesive 13, thus eliminating the need for a mold and other facilities for vulcanization bonding. This makes it possible to manufacture a magnetic encoder 11 with a large outer diameter at a low cost.

Abstract: A metal detector for detecting the presence of a ferrite object in the proximity of inductively coupled sensor having overlapping D shaped transmitter and receiver coils. The metal detector has a phase shift circuit to phase shifting a sensor output signal by a known amount and a switch operating in synchronization with an excitation signal of the sensor for sampling the amplitude of the phase shifted output signal.

Abstract: A plurality of transmitters on a logging tool are activated simultaneously at substantially the same frequency. When the transmitter outputs are phase-modulated using a mutually orthogonal set of modulating functions, it is possible to recover, from the signal at each receiver, a response corresponding to each of the transmitters.

Abstract: An displacement measurement device and associated method where displacement measurements of a movable member are obtained by an electromagnetic field sensor that need not move relative to the magnet or other electromagnetic field source. The electromagnetic field sensor senses disruptions in the electromagnetic field caused by movement of the movable member to provide an output indicative of the position of the actuator.

Abstract: A pre-amplifier circuit for connection to an antenna of a human-portable locator includes a differential amplifier/mixer pair and means for allowing a common-mode “phantom” signal to modulate a transfer function of the differential amplifier/mixer pair. The common-mode phantom signal modulates the transfer function of the differential pre-amplifier “onboard” the antenna without the usual requirement for onboard power supply and signal oscillator. This technique uses the same electronic components to provide both pre-amplification and mixing functions, thereby improving circuit performance-to-cost ratio, reducing mixer power consumption, situating the necessary signal oscillator remotely from the mixer, and greatly improving the available system bandwidth by limiting spectral transmission demands to the mixed signal bandwidth alone.

Abstract: Disclosed is a base module for a motion sensor, particularly a tacho generator, phase transducer, or transmission sensor for a motor vehicle. Said base module (22) comprises at least one busbar (11) for contacting an integrated circuit (36) used for sensing a motion. The base module (22) further comprises at least one wiring means (12, 14) which is arranged on the busbar (11). The busbar (11) and the wiring means (12) are surrounded at least in part by a sheath (26).

Abstract: A device rotates at least one static magnetic field about an axis, producing a rotating magnetic dipole field, and is movable in relation to the surface of the ground. The field is periodically sensed using a receiver to produce a receiver output responsive to the field. A positional relationship between the receiver and the device is monitored using the output. In one aspect, changing the positional relationship, by moving the device nearer to a boring tool which supports the receiver, causes an increase in accuracy of depth determination. In another aspect, determination of an actual overhead position of the boring tool, and its application, are described. Use of a plurality of measurements over at least one-half revolution of each magnet is disclosed. Establishing a surface radial direction toward a boring tool and resolution of multi-valued parameters is described. Calibration techniques, as well as a three transmitter configuration are also described.

Abstract: It is an object of the present invention to provide a method for investigating magnetic domains, the method capable of easily grasping behavior of the magnetic domains in a head manufacturing process, and further to provide a testing method of a magnetic head capable of evaluating whether the writing performance of the magnetic head is good or not. The method for investigating magnetic domains comprises supplying direct current (DC) to a coil of an electromagnetic transducer provided in a magnetic head for writing data onto a magnetic recording medium; measuring an inductance of the electromagnetic transducer at each current value while varying the current value of the direct current; and investigating behavior of magnetic domains in a magnetic core of the electromagnetic transducer based on a relationship between the current values and the inductances.

Abstract: To provide a tilt angle sensor that is capable of detecting acceleration, a tilt angle, and the like of a device to which the tilt sensor angle is mounted, and also capable of reducing the size and the cost with a simple structure. The tilt angle sensor comprises: a spring member having a fixed end a free end that has a flexibility to be bent at least in one direction; a magnetic field generating device for generating a magnetic field, which is mounted at the free end of the spring member; a magnetic field detecting device provided by facing the magnetic field generating device for detecting a direction of the magnetic field generated by the magnetic field generating device; and a damping device for giving a damping force to a bending action of the spring member.

Abstract: A resistivity device for downhole use with a nonconducting mud injects a current at a frequency sufficiently high to pass capacitively through the mud and a mud cake into the formation. The frequency is further selected so that the impedance due to the dielectric constant of the formation is small compared to the formation resistivity. Dual frequency measurements may be used to further minimize the effects of the mud and mud cake resistivity. When multiple frequency measurements are used, frequency focusing may be used to get an estimate of formation resistivity that is independent of near borehole effects.