Abstract: Tone wheel testing apparatus and the test method using the apparatus are disclosed. Tone wheel testing apparatus comprising a surface adjusting means for holding in the horizontal position an annular object to be tested to which a tone wheel is attached, the means comprising a pair of pressing members between which the object is held, and the one of the pressing members having a reference surface with which the tone wheel is contacted in order to make the tone wheel align in the rotary axis direction of the object, a rotatable chucking means for seizing the object so as to make the center of the object align with its rotary center when the object is held by the surface adjusting means, and a magnetic testing sensor disposed adjacent to the tone wheel of the object so as to face each other.

Abstract: A planar induction sensor for sensing of security features of documents having changing magnetic and (or) conducting properties is of a multilayer printed circuit board design. The sensor comprises a planar current transformer with a spiral-type primary coils and one or several turns of secondary coil in an adjacent layer of the printed circuit board. The secondary coil of the current transformer is connected to an operating coil, which is situated at a sensing edge of the sensor. The operating coil can be formed by external wires or can be incorporated in the circuit board of the current transformer. When a security element, made from the magnetic or conductive material moves past the sensing edge of the sensor, a change in inductance of the induction sensor occurs. In a preferred embodiment, two induction sensors with individual associated electronic circuits were located on opposite sides of validator channel.

Abstract: In a magnetically passive position sensor, a mechanical axis (11) and a magnetic axis (12) of a magnet (2) point toward the same contact spring element from two or more contact spring elements (5, 6). This results, in particular, in the end regions of the position sensor achieving a particularly high accuracy. The magnet (2) has a guide polygon (8) which is used to hold the magnet (2) in a holder (10) such that it cannot rotate.

Abstract: When cables run side by side over a longer distance, an alternating-current signal used for cable location can couple or ‘bleedover’ to neighboring cables. The coupled current flowing in the neighboring cable creates field distortion and makes position determination of the targeted cable difficult. The resulting magnetic field of both (or more) cables has a non-circular shape and is commonly known as a distorted field. Established methods for finding the position of the cable under investigation lead to inaccuracies or even wrong locates. The method described herein eliminates the field distortion that is due to the coupled cables by demodulating a phase reference signal placed on the cable by a transmitter into two signal strength constituents. The inphase signal represents the field strength of the targeted conductor and is substantially free of field distortion. The other quadrature signal contains the component of the field associated with distortion.

Abstract: A multi-mode resistivity tool measures at multiple depths into the near-borehole formation. By use of a four mode tool, measuring to four depths at the formation, a more accurate invasion zone resistivity measurement may be made than previously known. The tool itself is shown as including six concentric electrodes, although not every electrode is necessary for every mode.

Abstract: An apparatus and method is disclosed for inspecting contours formed along a predetermined region of a surface on a workpiece formed of an electrically conductive material using eddy current. A probe includes a longitudinal axis and is moveable along a path of travel to a static testing position stationary with respect to the predetermined region to be inspected on a workpiece. At least two coils are spaced longitudinally from one another and supported by the probe to be electrically excited with a predetermined frequency and amplitude while at the static testing position with the stationary probe. Sensors are provided for measuring the excitation voltage of each coil as eddy currents are induced in the electrically conductive material of the workpiece by the coils supported on the probe stationary at the static testing position with respect to the workpiece.

Abstract: A method is provided for conducting an electromagnetic induction survey of a geological formation penetrated by a borehole lined with a conductive casing. The method includes positioning a transmitter in the borehole, whereby the transmitter generates a transmitter magnetic moment, and positioning a distant receiver external of the borehole to detect a magnetic field induced by the transmitter, whereby the distant receiver is disposed across part of the formation from the borehole. Furthermore, an auxiliary receiver is positioned in the borehole proximate the transmitter to detect a magnetic field induced by the transmitter and attenuated by the conductive casing. Subsequently, a first casing attenuation factor that is applicable to the magnetic field measured by the auxiliary receiver is determined from a ratio of the measured magnetic field at the auxiliary receiver and the transmitter magnetic moment.