Abstract: Two A.C. output signals amplitude-modulated in accordance with two function values (sine and cosine) differing from each other in correspondence to a position-to-be-detected are received from a position sensor such as a resolver. By performing an addition or subtraction between a signal derived by shifting the electric phase of one of the received A.C. output signals by a predetermined angle, and the other received signal, two electric A.C. signals (sin(.omega.t .+-.d.+-..theta.), sin(.omega.t.+-.d-.theta.)) are electrically synthesized which have electric phase angles (.theta.) corresponding to the position-to-be-detected and are phase-shifted in opposite directions. ".+-.d" here represents phase variation error caused by factors, other than the position-to-be-detected, such as temperature change. In the synthesized two signals, the phase variation errors (.+-.d) appear in the same direction, while the phase differences (.theta.

Abstract: A magnetic force microscope for measuring a magnetic field near a surface of a magnetic sample includes a cantilever having a ferromagnetic probe at one end thereof and receiving a magnetic force from the surface of the magnetic sample. An oscillation device is fixed to another end of the cantilever for oscillating the cantilever. A voltage application device applies an alternating voltage to the oscillation device. A deflection detecting device detects the oscillation of the cantilever. A magnetic field generating device supplies a magnetic field near the ferromagnetic probe. By this construction, it is possible to correct fluctuations in magnetic field measurements using probes with different magnetic characteristics and magnetic field detecting sensitivity, and to measure an absolute value of the detected magnetic field. Further, since the ferromagnetic probe can be magnetized, it is possible to increase the magnetic sensitivity of the ferromagnetic probe.

Abstract: The invention relates to a method and a device for detecting a flashover between conductors in power transmission lines of different voltage levels suspended from the same towers and wherein the power lines are included in a power network where one of the power lines is stated to be a high-voltage power line (1) and where the other power lines are connected to the high-voltage line via transformers of a known transformer ratio (am) and internal impedance (ZXm) and wherein the line impedances (ZL) are known. Specific to the invention is that the fault current which is caused by a flashover is set to be equal to a detected current change in any of the phases in the high-voltage line. With this assumption an equation system can be set up with the aid of which the relative distance to fault n (0<n<1) can be determined. If the produced value of n lies within the stated region, this is interpreted as if an internal flashover has occurred.

Abstract: A highly sensitive magnetic field detecting system includes a DC superconducting quantum interference device (DC SQUID) for detecting a magnetic field to produce a signal voltage, and a flux locked loop (F.L.L.) circuit device for driving the DC SQUID. A phase detecting circuit forming part of the F.L.L. circuit device is composed of two phase detecting circuits having different phases to be detected. By adding the individual output signals of the two phase detecting circuits, the outputs can be unvaried at a phase difference equal to that of the detected phases of the two detecting circuits. The added signal is also unvaried with respect to the phase variations of the detected signal so that the metering procedures can be simplified without any necessity for phase adjustment. Further, the output signals obtained can be stable relative to the phase drifts of the signal to be transmitted from the DC SQUID to improve the metering precision.

Abstract: Position indicating apparatus that allows position detection with windings provided on only one of two members and an output signal in which the position of one of the members relative to the other member is directly encoded in the phase of the output signal. A first member has a plurality of spaced ferromagnetic protuberances. A second member, movable with respect to the first member, contains at least first, second and third poles located in proximity to the protuberances and spans 360 spatial degrees. Each pole contains a winding with one terminal of each winding connected to a common point. The windings are driven at a fundamental carrier frequency with individual signals of equal amplitude but different temporal phases that span 360 temporal degrees. Circuit means detect the phase of the resulting carrier signal at the common point, which phase is linearly representative of position.

Abstract: The present invention relates to a device and method for using a logging probe of small diameter with resect to a well in which it is to operate. The device of the invention is characterized in that it includes a widener for widening the diameter of said probe.

Abstract: A second receiver coil system (45a,45b) at right angles to the primary receiver coil system (40) in an induction logging tool (10) detects the skewness in the logging tool field pattern caused by the presence of assymmetrical formation structures (30). This skew signal, which provides a composite measure of the asymmetry of the formation structures (30), can be used to correct for horns produced in formation conductivity logs when the logging tool sonde (14) traverses interfaces between dipping beds. The skew signal can also be used to determine the dip and strike angles between such dipping beds.

Abstract: The subject of the invention is a device for non-destructive testing of long bodies (14) for structural faults by means of magnetizing the respective body (14). At least one magnetic field is directed onto the body (14). The structural faults in the body cause changes in the magnetic field pattern. The changes are picked up by magnetic field sensors (50, 52) arranged on or near the body surface. The respective body (14) is moved through the magnetic field, which has an inclination of preferably 45.degree. to the transportation direction (26) of the body (14). The magnetic field sensors (50, 52) are oriented transverse to the direction of the magnetic field.

Abstract: Apparatus for monitoring the dielectric composition of articles, particularly articles such as blisterpacks and laminated boards. The apparatus comprises an amplifying circuit including a capacitor between the electrodes (1, 3) of which an article (22) is moved in use. The gain of the amplifying circuit varies with the capacitance of the capacitor so that the amplifying circuit provides an output signal, the peak value of the output signal varying with the dielectric constant of the article (22) between the capacitor electrodes (1, 3). Typically the amplifying circuit includes an operational amplifier (9) the non-inverting input (10) of which is connected to a ground potential (6) and the inverting input (8) is connected to one electrode (3) of the capacitor. A feedback loop (11) is applied between the output (14) of the operational amplifier (9) and the inverting input (8) of the operational amplifier to force the inverting input to the same potential as the non-inverting input.

Abstract: For enabling a resolver to have absolute position sensing over a wide displacement range while still obtaining the resolution, accuracy and precision obtainable by operation in an incremental mode, the resolver is provided with a number of terminals for providing offset pitch phase indications as a function of position. A microcomputer is programmed to execute a decoding procedure for reading the offset pitch phase indications and from them computing the absolute position. This method is applicable to linear as well as rotary position sensing. By using multiplexing, digital signal processing and large-scale circuit integration of interfacing the resolver to the microcomputer, the method can achieve absolute position sensing with high reliability and low cost. The offset pitch phase indications are readily provided by inductive coupling between a multiplicity of windings, including a set of offset pitch windings connected to the terminals.

Abstract: A method and system for tracking a borehole by means of a probe and an externally produced magnetic field. The magnetic field is produced by a current configuration which facilitates the calculation of the magnitude and direction of the magnetic field at any point in space. In order to locate the probe, magnetometers within the probe are used to measure the magnetic field. Accelerometers within the probe allow the determination of the probe's orientation which enables the measured field vector to be compared to the calculated field vector and the probe's location thereby ascertained.

Abstract: The device includes a comparator (4) fed by a quasi-sinusoidal signal (3) delivered by a variable reluctance sensor, for converting alternations of the signal into pulses acceptable by digital computing means. According to the invention, the device includes a selectively connectable feedback resistor (R5) for varying the threshold of the comparator in such a way as to check, at a given frequency of the signal, the correctness of the amplitude of the signal (3) provided by the sensor. The device may be used for the checking of the operational state of a variable reluctance sensor delivering a signal indicating the speed of rotation of a shaft fitted in a motor vehicle.

Abstract: A method and apparatus for the determination of thickness of plastic materials, as well as of bonding and coating materials, by high frequency electric and magnetic alternating fields. The method enables a simple test of components, as well as of coatings and bondings, even if the plastic parts to be tested or the coatings or bondings to be tested are not yet completely cured and the surfaces to be tested are located, so as to be concealed or are accessible only with difficulty. The method and apparatus consists in that electrically conductive or ferromagnetic particles are added to the materials to be measured and subsequently the electrical conductivity or magnetic permeability is measured at the completed or coated test specimen by high-frequency electrical and magnetic alternating fields, whose progression in space and time is adapted to the measuring task.

Abstract: A differential transceiver transmission line integrity detector detects both open and short circuits in the transmission lines. The two transmission lines are terminated at both ends by selected impedances. A driver coupled to each of the transmission lines drives the lines with data signals. Signal levels on the lines are detected and compared with expected levels to generate line integrity indications. Both open and short conditions are detected and indicated by the line integrity indications.

Abstract: Machine for testing planar magnetic film with magnetic bubbles and which comprises a testing device and a magnetic head, wherein the magnetic head incorporates two polarization coils in the Helmholtz position and whereof the common axis is normal to the plane of the magnetic film and two flat coils whose axes are perpendicular to one another and parallel to the plane of the magnetic film, the first of the polarization coils being arranged within the flat coils which are themselves arranged one within the other and on the same side of the magnetic film, while the test device and the second polarization coil are arranged on the other side of the magnetic film.

Abstract: An electric meter particularly characterized by a small number of moving parts and simplified assembly by virtue of fixed cooperating locating surfaces on the elements and sub-assemblies of the meter. A magnetic circuit including a yoke and magnet are constructed to snap into an insulating base in a predetermined position on the base. A coil assembly initially including integral elements for connection of pivot bearings or taut bands is accurately positioned for rotation on the supporting base by inserting the assembly into the base. Cooperating locating surfaces provide for accurate predetermined positioning of the axis of rotation of the coil relative to the magnetic circuit.

Abstract: This disclosure is concerned with novel current-tracing of short circuits in printed circuit boards and similar systems by novel test excitation of the conductors with tracing of the phase polarities of the fields generated therein.

Abstract: The present invention relates to a process and a device for prospecting the ocean bed by measuring electromagnetic fields.A loop 4 emitting electromagnetic rays is towed by its electricity supply cables 3. These cables are twisted and possess a sufficient cross section to reduce their electrical resistance. The loop per se has a low reactance owing to the low frequency which is used. The pick-ups for the components of the magnetic or electric fields, which make it possible to detect the variations in resistivity of the ground, are situated with the supply generator for the loop 4 on the boat 1.The present invention is intended for use in prospecting for mineral resources situated under water and, more generally, for all geological studies carried out on ground covered by water.

Abstract: An induction balance metal detector is described which is capable of discriminating between different types of metal objects, such as bottle caps and coins, by amplitude discrimination of their corresponding receive signals. In addition, the detector is provided with a tuning control which is used to eliminate the effect of ferrous mineral soil on the output signal of the receive coil. The discriminate control changes the phase of the residual output signal of the receive coil to set the quiescent operating point of the metal detector to a selected angle between about zero and -90.degree. relative to the component of the receive coil signal produced by the presence of magnetic mineral soil, and the tuning control adjusts the amplitude of the residual signal to an audio threshold level.