There are so many metal detectors capable of discriminating targets based on. 2) This system may be subjected either to a pressure stress, or an acoustic.
System of Electromagnetic Detection and Identification of Objects by Acoustic Excitation.This device makes it possible to locate and identify remotely, any object comprising a Piezo-Electro-Magnetic (PEM) sensor. The system relates to both the PEM sensor, the exciter or device for exciting it by an acoustic wave, and the receiver-reader or device for reading the electromagnetic signal returned by the sensor. This device is designed for the remote detection of objects carrying or integrating this type of PEM marker through a medium that can be homogeneous or heterogeneous solid, liquid or gaseous type. The present invention relates to a system for the electromagnetic detection and identification of objects by acoustic excitation makes it possible to locate and identify remotely any object comprising a Piezo-Electro-Magnetic (PEM) sensor. The patented system concerns both the PEM sensor, the exciter or device for exciting an acoustic wave, and the receiver-reader or device for reading electromagnetic signal returned by the sensor.
(Figure 1) The originality of this invention lies in the possibility offered by this type of PEM marker to be detected remotely through a medium that can be homogeneous or heterogeneous liquid or gaseous solid type. DEFINITIONS A marker will be called a material or set of materials or complex device, placed near or on an object for which remote location is desired, and capable of delivering a characteristic signal.A piezoelectric component is made from a polarizable material, under the action of an external pressure (stress) or under the action of a vibration, delivers electric current component electromagnetic consists of a material or inductance capable of generating a field or an electromagnetic wave (conventional coil inductance L).
This marker system is capable of being excited by an acoustic wave and emitting an electromagnetic wave.Hence our definition of ' Piezo-Electro-Magnetic marker' or PEM marker. Examples of piezoelectric material adapted: Sintered ceramic PZT with approximate chemical formula Pb Zr 0.5 Ti 0.5 03.STATE OF THE ART.The search for buried objects has been the subject of numerous studies. There are thus many metal detectors capable of discriminating the targets as a function of their conductivity and freeing themselves from the mineralization of the soil (1, 2 and 3).These detectors are based on the principle of detection by eddy currents. These are easily detectable to depths of about 60 cm, using coil-type antennas (magnetometers) 4.Other detection systems currently exist on the market: these are mining exploration radars. These can locate objects or metals buried at great depths (200 - 300 m), but provided they are large volumes. Detectors are essentially based on measurements of magnetic moments and hyteresis measurements (5 and 6).magnetic location detection and positioning systems already exist, particularly in the field of underwater navigation. 1) transceiver system describes a principle of location and identification of objects at a distance, without contact, objects being buried or apparent.
The principle used for the detection of piezoelectromagnetism. 2) The transmitter is a system generating a pulse in the form of a wave or an acoustic wave train. 3) The marker is a system consisting of a piezoelectric element P connected to an antenna via a possible transfer device T (non-linear element, electronic chip, coding device, etc.). 4) The transfer device T is a non-linear element, an electronic chip, a coding device. 5) The piezoelectric element P is a ceramic material shaped to be tuned to characteristic frequencies. It is capable of delivering an electric pulse, correlated to the acoustic excitation, to the transfer circuit, then to the antenna A. 6) The antenna A is a conductive device (inductance type or RLC circuit) capable of generating a field magnetic correlated with the electric current delivered by the piezoelectric device transfer function.
7) receiver consists of a receiving antenna adapted to the emission of the marker, and connected to a signal processing system. 8) receiver is coupled to the transmitter. 9) signal processing makes it possible to analyze the shape of the return signal, the amplitudes and phase shifts.
10) The detection is carried out through homogeneous or heterogeneous solid media, liquid and possibly gaseous. The selective character of the detection is ensured by a distribution or association of markers with diversified characters (frequency, transfer function, etc.). 12) The association of different markers makes it possible, as a differential measure, to evaluate the distance between the transmitter and the marker. 13) The system described above allows the location and identification of any object that has been associated with a given marker. 14) Potential applications. 15) By way of example, some applications - locating cables, pipes and buried or buried structures; - location of clothing (avalanches, eboulements.); - mine detection; - detection of marking markers (public works); - coding of car spare parts, avionics, industrial.