Abstract: A method of computing the rotating speed of a rotating body includes the steps of setting speed computation reference time periods with respect to a pulse train signal obtained from the output of a rotating speed sensor; measuring time length from the last pulse edge in the previous speed computation reference time period to the last pulse edge in the current speed computation reference time period; and computing the rotating speed of the rotating body on the basis of the result of the time length measurement. The time point when the previous procedure of speed computation terminated corresponds to the time point when the current procedure of speed computation starts, thus making it possible to achieve continuous speed computation. In this way, an enhanced accuracy can be achieved in speed measurement for low speed range, which leads to improved control performance in anti-lock control and traction control for the low speed range.

Abstract: A device for determining the rotary-angle position of rotary drives which can also determine the rotary speed. A magnet rotor generating a rotating magnetic field is provided for the purpose of determining the rotary speed with a cam disc suited for screening magnetic field lines, and to arrange coacting inductive transmitter and receiver heads on both sides of the cam disc, for determining the rotary-angle position. Due to the fact that the electromagnetic radiation emitted by the transmitter head is screened, the output signal of the receiver heads obtained is an envelope-modulated signal which can be evaluated for determining the position, for example by phase comparisons with additional envelope-modulated output signals of other receiver heads. The axial magnetization lines emanating simultaneously from the magnet rotor serve for inducing electric voltages in flat coils arranged axially before the magnet rotor, in overlapping annular shape.

Abstract: In a method for calibrating multi-channel SQUID systems having gradiometers of an arbitrary order, calibration coils, each having the same number of ampere turns are symmetrically arranged at identical distances between the parallel coil planes with respect to every gradiometer coil, so that every gradiometer coil is penetrated by a common, oppositely directed magnetic field generated by the calibration coils. The field that the calibration coils produce at the locations of the gradiometer coils are numerically calculated to obtain a net gradient field value which is divided by the measured voltage at the output of the allocated SQUID electronics in order to calculate the calibration factor.

Abstract: An array of SQUID detectors to map the magnetic field associated with test currents flowing in the component to be tested. The SQUID is an ultrasensitive, miniature device that transduces a faint magnetic field to a measurable voltage. Perturbation occurs in the test currents and the associated magnetic field at physical defects or inhomogeneities. Multi-dimensional test currents are injected into the component being tested; the injection being made between specific electrodes by varying the direction of the current until it is normal to the direction of the defect to maximize and amplify the effect of the perturbation. The perturbation is detected by the SQUID grid which pinpoints the location, orientation, and size of the defect. The frequency of the injected current can be made to sweep the spectrum from DC to the highest response limit of the SQUID to scan for defects at various depths.

Abstract: A Hall sensor has at least one Hall element connected to the input of a differential high pass filter which includes a series branch circuit made up of two outer resistors and a central capacitor connected between the two resistors, a first summing circuit with inputs connected across the capacitor plus one of the branch resistors, a second summing circuit connected across the capacitor plus the other of the branch resistors, and a subtraction circuit having the input connected to the outputs of said first and second summing circuits. The subtraction circuit may be a differential amplifier or a differential comparator such as a differential Schmitt trigger circuit. This sensor is particularly advantageous in an electrically noisy environment, for example in use as a combustion-engine-vehicle gear tooth counting sensor, where the high common mode rejection feature of this Hall sensor reduces the chances for false counting.

Abstract: In a method for nondestructive measurement of the heat affected zone of an identification code on a nuclear fuel rod tube, the change in impedance of an electromagnetic coil produced by a portion of the tube to be etched with a bar code is measured before and after the etching of the bar code is performed by use of laser power. The impedance change in the coil produced by the bar code-bearing tube portion is compared with the impedance change produced in the coil by the same tube portion before the bar code is generated thereon to determine whether a maximum allowed depth of the heat affected zone of the tube portion has been exceeded.

Abstract: A tachometer device having a sensor generating an electrical signal at a frequency which is proportional to a speed to be detected, an operating drive member, and electrical link means connecting the sensor to the operating drive member. A device for limiting frequency variations in the pulses applied to the operating drive member is interposed between the sensor and said operating drive member.

Abstract: An assembly formed by an electronic circuit in which a microprocessor is included that emits a signal from which additional signals are generated by a frequency synthesizer. These signals are applied to coils which form the emitting antenna, after being filtered and amplified. From these signals, the sample signal is generated and is picked up by other receiving antennas. After being amplified and filtered and all the distortion elements removed, the picked up signals are applied to proper frequency filters to obtain at the output signals having amplitudes proportional to those generated in the sample.

Abstract: A system (apparatus and method) for measuring a revolution speed of a rotary member improves accuracy by estimating the speed during a unit operation period in response to pulse signals detected from the rotary member. When a pulse signal is not detected, the system obtains the revolution speed by selecting the lesser of a first estimated value and a second estimated value. The first estimated value is determined on the basis of the calculated revolution speed during the previous unit operation period and also the calculated acceleration during that previous operation period. The second estimated value is determined on the basis of a lapse time between a detected time of the last signal and the completion time of the current unit operation period.

Abstract: In an eddy-current measuring device, a permanent magnet (2) which is arranged fixed for rotation on a drive shaft (1) is magnetized axially. An eddy-current element (4) has the shaped of a disk and is located with slight axial spacing from the permanent magnet (2) on a pointer shaft (3). On the top of the eddy-current element (4) and below the permanent magnet (2), a congruent flux return element (8,9) is provided in each case.

Abstract: The present invention is a thin bed resistivity well logging system and method which includes a transmitter transmitting electromagnetic energy into an earth formation, from within a borehole traversing the earth's formation, at a frequency lying within a range of frequencies from 500 kilohertz to 4 megahertz. The system, a portion of which is located in the borehole, determines the true resistivity of a thin strata in accordance with the transmitted electromagnetic energy that has propagated through the earth's formation.

Abstract: When observing or setting changeable positions of respective movable components of a machine, such as movable saws of a multiple cut sawing machine, each linear position-displacement transducer used has the wave guide housing thereof, made of sufficient length to receive, instead of one permanent magnet, several overall cylindrical electromagnets serving as flux generators. Each electromagnet: has a centered hole, to permit the movement thereof along the wave guide; and has four electromagnets equally radially spaced in a radial plane, with their commonly positioned north poles, forming an overall central north pole, surrounding the center hole, which is formed by a non ferrous tube, and with their radially spaced south poles being adjacent to an encircling soft iron band.

Abstract: A wheel speed sensor comprises a Hall device disposed in a pocket in a cavity of a plastic housing. The cavity is filled with potting compound to capture and enclose the Hall device. Flux issued from a magnet that rotates with the wheel acts upon the Hall device and is concentrated on the Hall device by ferromagnetic fragments interspersed throughout the potting compound.

Abstract: A reference standard and a method for manufacturing a reference standard for use in calibrating an eddy current probe is disclosed. The reference standard is produced from a block of metal that is deformed by an indentation tool to provide a notch of prescribed dimensions. The reference standard is compressed along an axis substantially transverse to the longitudinal axis of the notch to substantially close the notch. A family of reference standards formed in this manner can be produced to calibrate an eddy current probe prior to use of the probe in evaluating metal components such as aircraft framework for the presence of fatigue cracks and the like.

Abstract: A non-contact level measurement system for monitoring distances with very high accuracy between a sensor coil and a metallic object such as a molten liquid level over either very narrow or extended distances. Means are provided for compensating for temperature and other non-linear effects including other inductive fields, environmental changes and the like. The system incorporates an L-C resonant circuit connected between the output of an oscillator and the input of an operational amplifier.

Abstract: A linear displacement transducer comprises a winding, a magnetic core which is linearly displaceable relatively to the winding, and a source for energizing the winding with a constant RMS alternating current at a frequency sufficiently high for the resistive losses in the magnetic core to cause the voltage across the winding to vary substantially linearly relative to the linear displacement of the magnetic core. The frequency may, for example, be in the range 10 to 20 kHz, and a temperature sensing winding may be associated with the winding to enable the output from the transducer to be compensated for temperature changes, or the winding may be used in time-division multiplex for this purpose.

Abstract: A pulsed eddy current testing system for detecting defects in a part. A probe carries an exciting pulse in one coil and receives a measuring signal in a second coil. The measuring signal is sampled at two instants defined by short and long time lags. The two amplitudes obtained are plotted in a representative plane having two reference axes. The point having the signals as coordinates describes a figure eight, when the part has a defect. The size and orientation of the figure gives information on the defect in the part.

Abstract: A displacement transducer utilizes a torsional strain waveguide having a magnetic member that is adjustable positioned along the length of the waveguide, when an electrical current pulse is passed along the waveguide and reaches the magnet torsional strain wave is created in the waveguide. The torsional strain wave will be reflected back toward a mounting end of the waveguide where a converter or sensor is positioned to sense the strain wave signal and convert it to an electrical output signal. The strain wave signals have signal lobes of a time period. A waveguide mounting block supports the waveguide at the mounting end and provides a reflection point for the torsional strain waves. The waveguide mounting block is on an opposite side of the signal sensor from the magnet.

Abstract: A flux scanner head generates a unidirectional magnetic field external to the head adjacent a scanning surface thereof. Workpieces to be subjected to magnetic particle inspection may be successively passed through, held in, or otherwise associated with, the unidirectional field at different angles to achieve magnetization along multiple axes, without physical or electrical contact with the workpiece. The scanner head is usable with both residual and continuous methods of magnetic particle inspection, and as either a hand-held or fixed-mount system. The scanner head itself incorporates a coil having a plurality of turns with a ferromagnetic core separating such turns so as to intensify and direct outward and external to the surface of the scanner head the magnetic field generated by current flow through the coil.

Abstract: The invention is directed to an apparatus for determining the proportion of substances having paramagnetic characteristics, such as oxygen, in a mixture of substances. The apparatus has a housing and the mixture of substances is passed along an arrangement of four magnetic field sources by a rotatable cuvette arrangement mounted in the housing. The apparatus is improved in that the effect of external disturbing influences on the penetration of the cuvette by the magnetic field is reduced and so that the measuring characteristics are independent of the position of the plurality of magnetic field generating units. For this purpose, the arrangement of the magnetic field sources is simply disposed at one side of the housing lying opposite to the rotating surface of the cuvette arrangement facing toward the drive shaft. The arrangement of magnetic field sources includes a carrier plate on which the magnetic field sources are accommodated and carry respective measuring field coils.