Abstract: The method and sensor unit allow the location and detection of metallic or metal-containing objects and materials. A coil arrangement (1.2) comprises a transmission coil and a reception coil, which are arranged on top of one another, wherein the reception coil generates a reception coil output signal. A closed compensation control regulates the reception coil output signal in the receiving coil for compensating changes which occur in the detection range of the reception coil and influence the reception coil. To this end, compensation currents are fed into the receiving branch of the reception coil and are controlled relative to each other such that the reception coil output signal or average values which are detected from the reception coil output signal after demodulation are continuously regulated relative to each other to zero even in the case of metal influence. As a result, a coil with an unregulated transmission current can be used, in which a zero output signal is continuously generated.

Abstract: A magneto-optic surface includes a support; at least two moving elements; each of the moving elements including at least one anchoring point to the support and at least one moving part movable with respect to the support, the moving part including at least one magnetic part; the support and the moving elements being laid out in such a way that under the effect of an external magnetic field, at least one of the moving elements moves with respect to the support such that the optical properties of the magneto-optic surface are modified.

Abstract: The system utilizes electroscan equipment including a voltage source and current meter with a cable having one end grounded and one end having an electric probe thereon sized to fit within an underground pipe. The probe is able to complete an electric circuit back to ground when the probe is adjacent a defect through which electric currents can pass, thus producing varying electric current. A cable reel is provided with portions of the cable supported thereon and with a cable distance sensor coupled to the reel along with the current meter and voltage source in the form of a battery. The current meter and distance sensor transmit wireless signals to an on-site processor, such as a smartphone, for on-site data evaluation. Such unconditioned data is also transmitted to a remote location for conditioning of the data and retransmission of the conditioned data back to the on-site processor.

Abstract: A measuring device configured to detect a metal object includes two emission coils configured to produce superimposed magnetic fields. The measuring device also includes a device configured to determine a differential voltage between the emission coils. The measuring device further includes a control device configured to supply the emission coils with alternating voltages such that the value of an AC voltage component of the differential voltage, which is time synchronized with the alternating voltage, is minimized. The control device is configured to detect the metal object when the ratio of the alternating voltages does not correspond to the ratio of the impedances of the emission coils when the metal object is not there.

Abstract: A downhole activation system within a tubular. The system includes an axially movable mover. A first magnet attached to the mover. The first magnet axially movable with the mover. A second magnet separated from the first magnet. The second magnet magnetically repulsed by the first magnet. A biasing device urging the second magnet towards the first magnet; wherein movement of the first magnet via the mover towards the second magnet moves the second magnet in a direction against the biasing device. Also included is a method of activating an activatable member in a downhole tubular.

Abstract: Embodiments related to the generation of magnetic bias fields for magnetic sensing are described and depicted. In one embodiment, a sensor includes at least one magnetosensitive element, and a magnetic body with an opening, the magnetic body comprising magnetic material, the magnetic body having inclined surface sections shaped by the opening, wherein the sensor is arranged within the opening such that the magnetosensitive element is in lateral directions bounded by the inclined surface sections.

Abstract: Disclosed is a Hall Effect instrument with the capability of compensating for temperature drift consistently, accurately and in real time of operation. The instrument embodies a four-point ohmmeter circuit measuring Hall Effect sensor resistance and tracking the effect of temperature on the Hall Effect sensor. The instrument takes into account a relationship between the temperature and a temperature compensation index on a per probe basis, which has exhibited a deterministic difference observed by the present inventor.

Abstract: Inductive adjustment of the core-fitted coil (16) of an eddy-current distance sensor (11) can be avoided if the coil (16) fills a physically predetermined annular space between the winding support (17) of the plastic coil former (15) and its flanges (18-19) as well as the wall (21) of a pot (20) composed of ferromagnetic material, which is placed over the rearward, smaller flange (18) and whose end face (21) rests against an annular area of the front, larger flange (19) with the same diameter as the pot (20). The ferromagnetic coil core (31) which engages coaxially in the winding support (17) can therefore be arranged on the base (24) in the pot (20) and can therefore be mounted as part of the pot (20).

Abstract: A hall effect current sensor including a mounting bracket, a sensor assembly, and a sensor core. The sensor assembly includes a flux sensor. The sensor core includes a first portion and a second portion. The first portion and the second portion define a first air gap and a second air gap between the first portion and the second portion. The first air gap is adapted to receive the sensor assembly.

Abstract: A substantially planar eddy-current sensor having durability enhancing pillars in an active region is provided. The pillars are distributed and sized so as to have limited effect on the sensor's performance. When the sensor is mounted on a component such that the sensor experiences forces on a top and bottom surface, the pillars bear the load reducing the load bore by the active elements (e.g., drive winding, sense elements). A sensor with redundant drive windings and/or redundant sense elements is disclosed. The redundant elements may be connected to separate electronics. Another aspect relates to providing a reference transformer for calibration of a sensor. The secondary windings of the reference transformer are connected in series with the sense elements of the sensor to be calibrated. Transimpedance measurements are made when the drive winding of the reference transformer is excited. The measurements are used to correct transimpedance measurements made when the drive winding of the sensor is excited.

Abstract: A resistivity measuring tool used in a drillstring having a drill bit on a distal end for drilling a wellbore in a formation includes a tool body having a longitudinal axis, a sensor configured to measure the angular position of the tool body relative to the wellbore, at least one axial antenna including a wire winding for generating an axial magnetic moment parallel with the longitudinal axis, and at least one transverse antenna. The transverse antenna includes an antenna body disposed within a pocket extending radially inward from an outer surface of the tool body and one or more turns of wire wound around the antenna body, the wire winding generating a transverse magnetic moment orthogonal to the longitudinal axis.

Abstract: Embodiments relate to magnetic field sensors, such as magnetic field angle sensors with generally on-axis arrangements of sensor elements relative to a rotation axis of a magnet or shaft. The shaft comprises or is coupled to an end portion that comprises a soft magnetic material, in embodiments, with the end portion having an end surface proximate the sensor that is rotationally asymmetric with respect to the rotation axis running through the length of the shaft. The sensor comprises at least three magnetic field sensing elements arranged in a plane generally perpendicular to the shaft and rotation axis. Circuitry forming part of or coupled to the sensor is configured to estimate a rotational position of the shaft by combining the signals of the at least three magnetic field sensing elements.

Abstract: One embodiment of the present invention relates to a method and apparatus for removing the effect of contact resistances for Hall effect device contacts. In one embodiment, the apparatus comprises a Hall effect device comprising a plurality of force and sense contact pairs. The force and sense contact pairs comprise a force contact and a separate and distinct sense contact. The force contact is configured to act as a supply terminal that receive an input signal while the sense contact is configured act as an output terminal to provide an output signal indicative of a measured magnetic field value. By utilizing separate contacts for inputting a signal (e.g., an applied current) and reading out a signal (e.g., an induced voltage) the non-linearities generated by contact resistances may be removed, thereby minimizing the zero point offset voltage of the measured magnetic field.

Abstract: A magnetic medium is magnetized in the relative movement direction at a predefined pitch km and a magnetic sensor includes plural magnetoresistive elements whose electrical resistance value changes depending on a magnetic field at a place where the magnetoresistive element is disposed. A position where the magnetoresistive element is disposed is defined as a reference position and, in addition to the magnetoresistive element of this reference position, the magnetoresistive elements as harmonic reducing patterns are disposed at the following positions, with P(n) defined as the n-th prime: a position offset by ?m/(2·P(n)) from the reference position toward at least one side of the relative movement direction, wherein N?n>1 and N is a natural number satisfying N>3, and a position further offset by ?m/(2·P(L+1)) from a position offset by ?m/(2·P(L)), wherein 1<L<N.

Abstract: A steering tool is movable by a drill string to form an underground bore along an intended path. A sensing arrangement of the steering tool detects its pitch and yaw orientations at a series of spaced apart positions along the bore, each position is characterized by a measured extension of the drill string. The steering tool further includes a receiver. At least one marker is positioned proximate to the intended path, for transmitting a rotating dipole field to expose a portion of the intended path to the field for reception by the receiver. The detected pitch orientation, the detected yaw orientation and the measured extension of the drill string are used in conjunction with magnetic information from the receiver to locate the steering tool. The steering tool may automatically use the magnetic information when it is available. A customized overall position determination accuracy can be provided along the intended path.

Abstract: An optical pumping magnetometer is provided that is capable of improving the response of the magnetometer with respect to a magnetic field that varies with a period shorter than the transverse relaxation time of electron spin of an alkali metal atom.

Abstract: A real-time calibration system and method for a mobile device having an onboard magnetometer uses an estimator to estimate magnetometer calibration parameters and a magnetic field external to the mobile device (e.g., the earth magnetic field). The calibration parameters can be used to calibrate uncalibrated magnetometer readings output from the onboard magnetometer. The external magnetic field can be modeled as a weighted combination of a past estimate of the external magnetic field and the asymptotic mean of that magnetic field, perturbed by a random noise (e.g., Gaussian random noise). The weight can be adjusted based on a measure of the statistical uncertainty of the estimated calibration parameters and the estimated external magnetic field. The asymptotic mean of the external magnetic field can be modeled as a time average of the estimated external magnetic field.

Abstract: A system for position sensing includes an incremental track including a plurality of sectors and a measurement subsystem. The measurement subsystem includes at least two differential read-heads each having at least one primary coil and at least two differential secondary coils, the at least two differential secondary coils of one of the at least two differential read-heads configured to generate output signals having their amplitudes modulated by the sectors of the incremental track and the at least two differential secondary coils of the other of said two differential read-heads configured to generate output signals having their amplitudes modulated by the sectors of the incremental track.

Abstract: A liquid density sensor has a sensing module, a sensing rod and a floating device. The sensing module has a control circuit having computing functions. The sensing rod has a sensing line electrically connected to the control circuit. The floating device has a first magnetic unit and a floating ball mounted therein. The sensing rod is mounted through the floating device and the floating ball. The floating ball has a second magnetic unit. A specific gravity of the floating ball is lower than that of the floating device. The control circuit calculates a liquid density of liquid based on a distance between the first magnetic unit and the second magnetic unit according to a linear formula.

Abstract: A variable-reluctance magnetic detection head delivers an electrical signal (Uin) and a rising wavefront of the electrical signal is compared with a first threshold (Th) in order to switch from a first state (B0) to a second state (B1), and a falling wavefront is compared with a second threshold (Tb) lower than the first threshold (Th) in order to switch from the second state (B1) to the first state (B0). In a diagnostics step, the first threshold (Th) or the second threshold (Tb) is modified, bringing these thresholds closer together, and a magnetic detection head is diagnosed as being defective if the duty cycle of the second state (B1) is modified during the diagnostics step by a value higher than a diagnostics threshold predetermined in relation to a reference level.