Patent ID: 8166820

Claim:
Method for detecting a sonic imprint of a three-dimensional object, wherein there is provided a plurality of vibration detecting means, firmly fixed in predetermined detection points on the external surface of the object, the method comprising the following steps: a) induction of vibrations in the object by means of a source of mechanical strain in a point of predetermined application points for the application of said strain; b) acquisition of analogical signals coming from said detecting means and conversion of the signals from analogical to digital ones; c) repetition of the steps a) and b) for a predetermined number of times; d) repetition of the steps a) to c) for the remaining predetermined application points for the application of the strain; e) spectral analysis of resonance frequencies for each of the detecting means and for each set of inductions of vibrations in a same application point for the application of the strain; f) normalization of the frequency spectra, comparison of the normalized spectra and selection of one or more groups of normalized spectra which are similar each other; g) processing of the average of the one or more groups of similar normalized spectra, obtaining one or more normalized averaged spectra defining the sonic imprint of the object; wherein there is provided a coding of said one or more normalized averaged spectra, having as output a digital cryptic bar code and/or an analogical bar code.