Summary of Non-traditional Methods for Metal Detection and Discrimination

This paper describes three different possibilities how to detect and distinguish between different metal garbage and mine (especially Anti-Personnel mines - AP) or UXO (unexploded ordnance). A comparison of three unconventional excitation polyharmonic signals for an eddy current metal detector is presented. These signals are linear frequency sweep sinusoidal, step sweep sinusoidal, and sinc signals. Thanks to this we obtained a frequency characteristic of a detected object over a wide range of frequencies and obtained more detailed view about object than with classical methods. Amplitude and phase spectra, polar graphs as well as real and imaginary parts ot detector signal output are presented. Based on the measurements and the analyses, the distinguishing between different objects can be done in terms of the electromagnetic properties (conductivity and permeability). Polar graphs could be used for an object's interpretation and for the manual discrimination.