Abstract
The authors theoretically and experimentally substantiated the use of the spectral method for processing a signal of the vortex-current metal detector for dichotomous differentiation between metals. Results of experimental research that prove the possibility of using spectral analysis for differentiation between metals were presented. The vortex-current method for detection of hidden metal objects was analyzed. It was indicated that amplitude of output VCD signal is determined by electric conductivity of material of a hidden object and its magnetic permeability. It was shown that the spectral density of a signal can be an informative feature. The authors designed and fabricated a mockup of the vortex-current device, the special features of which include modularity, which, if necessary, makes it possible to replace quickly each of the modules. The developed algorithm of normalization of signals allows an operator to choose freely a scan mode and compare correctly VCD signals with reference signals. Research results show that it is possible to distinguish easily between the spectra of ferrous metals and those of non-ferrous metals. Spectral methods can be applied both for dichotomous analysis of hidden metal objects and for analysis of the type of metal in the subgroup of non-ferrous metals under condition of using highly sensitive spectroanalyzers with measurement error not exceeding 1 %. It was shown that advantage of the spectral method for analysis of signals of vortex-current transducer is identification of hidden objects by type of metal. The use of spectral methods for detection of hidden metals offers a new property – distant analysis of composition of detected metal objects.
Highlights
The problem of detection of hidden metal objects in different media has always been important
Metal detectors are usually based on the vortex-current method for detection of the objects [1], which by their electrical or magnetic properties are different from the medium, in which hidden items are found
The problem of identification and analysis of the composition of metal objects without their being damaged, including the ones hidden in another dielectric medium is relevant
Summary
The problem of detection of hidden metal objects in different media has always been important. The disadvantage of X-ray fluorescent devices can be the fact that they do not register elements with a number by order less than eleven, which does not allow analysis of materials containing carbon, which applies to iron and steel. They are less accurate, and the surface of an object under investigation must be cleaned from paint and rust. That is, this method requires existence of a sample of metal and does not make it possible to determine its composition at the distance, without laboratory tests. The problem of identification and analysis of the composition of metal objects without their being damaged, including the ones hidden in another dielectric medium is relevant
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