Abstract: An eddy current probe for the nondestructive testing of electrically conductive material parts comprises four identical active elements (10a, 10b, 10c, 10d), at lease in pairs, whose centers are arranged in accordance with a square or a quadrilateral, whose diagonals intersect at right angles and have an intersection point located in the center of one of them. The major axes (18a, 18b, 18c, 18d) of said elements are oriented perpendicular to the plane of the square or intersect at the same point on the normal to the center of the square. The active elements are generally windings. Preferably, opposite windings (10a, 10c and 10b, 10d) of the square are connected pairwise in series, so as to produce magnetic fields, which are summated according to the diagonals of the square and the two pairs are connected to one another according to a differential arrangement or circuit.

Abstract: A device for the simultaneous demodulation of a multifrequency signal comprising a processor in which demodulation takes place by calculation. An injector's output signal is multiplied by a complex signal having sinusoids of varying frequencies corresponding to frequency-shifted carriers, thereby transposing the injector's signal on intermediate frequencies.

Abstract: The present invention relates to a digital oscillator comprising an oscillator (40), a counter (41), a memory (42), a digital-analog converter (43) and a low-pass filter (44). The memory is able to directly store a complex signal, rendering the use of a real time calculating unit unnecessary.

Abstract: For the nondestructive testing of an electrically conductive part (T), an eddy current sensor (22a) is proposed having two transmitter windings (26) and one receiver winding (28). These three windings are arranged symmetrically with respect to a reference plane (P1) oriented perpendicular to the surface of the part (T). The receiver winding (28) is placed between the active portions (26a) of the emitter windings (26) and perpendicular to the plane (P1), whereas the transmitter windings (26) are substantially parallel to said plane. The coils and connections of the transmitter windings are such that the receiver winding is not traversed by any current in the absence of a fault. A tool for testing a tube (T), such as a steam generator tube, has two sensors oriented at right angles to one another.

Abstract: Probe-holding apparatus for holding a probe for checking steam generator tubes particularly in a nuclear reactor installation. The apparatus comprises a telescopic arm supported via a ball and socket joint from a support mounted in or near an access aperture in a chamber at one end of the steam generator. A probe guide is carried by a carriage pivotally mounted at the other end of the telescopic arm. The carriage includes an endless belt having a series of spaced projections which engage into the ends of the tubes, the projections being spaced by a distance equal to the tube pitch or a multiple thereof. The belt is driven by a stepping motor in order to move the carriage and place the probe guide opposite different ones of the tubes.