Commissariat a L'energie Atomique

Francis Robach

Roland Blanpain

Jean Berthier

Pascal Manet

A process is described to detect conducting objects buried in the ground by sending a series of electromagnetic pulses and the return signal. The signal characteristics stored in the database are sets of numerical data which each define characteristics of decreasing curves of the values of previously-received signals then, in a search phase, the numerical values of samples ranked 1, 2, . . . n are recorded, representing a real decreasing curve of a received signal. The average real decreasing curve is created by determination of the average value of the samples, each of which represents the average value of the values of the samples of the same rank. A value representing the difference between the set of characteristics of the real average decreasing curve and each of the sets with the same database characteristics is calculated. The smallest of the differences is compared with the threshold value. There is detection if at least one difference is less than the predetermined threshold, the object and its burying depth being defined as the object in the database which had the minimum difference value.

Process for electromagnetic detection of conducting objects

The apparatus includes a pair of electrodes which makes it possible to channel a current density creating the current which induces a magnetic field in one or more induction coils. This magnetic field is measured with the aid of one or more magnetometric transducers. The electric/magnetic transfer rate of the coils and the conductivity of the conductive medium are known, so that the value of the electric field is deduced on the basis of Ohm's law. The local magnetic field is previously measured so as to take account thereof when measuring the induced magnetic field.

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Biviers, France

Francis Robach