1. Method of detecting and identifying substances or mixtures and/or determining their characteristics, which comprises irradiation of the inspected object by pulse signals of fixed duration, reception of the signal reflected by controllable object, amplification and analogue-to-digital conversion of the received signal and comparison of parameters of the converted signal to prerecorded reference values, wherein the inspected object is irradiated by a single wave pulse with a frequency of 20 kHz to 200 MHz or a series of such pulses, the analogue-to-digital conversion of the received signal is up to at least 128 discrete values followed by: formation of output detailing wavelet coefficients Di,k (where i varies from 1 to N) and of output approximating wavelet coefficients A N ,k by means of fast discrete wavelet transformation of the digitized signal, performed by Mallat's pyramidal algorithm and orthogonal base functions (of Haar, of Daubechies, coiflets, simlets, etc.), when using a suitable number of transformation levels N, comprising high frequency ( 4. i ) and low frequency ( 5. i ) wavelet filtering and binary decimation ( 6. i ) after each filtering at each level i, until at least one approximating and at least one detailing wavelet coefficient is obtained after the last transformation level, whereat only the approximating wavelet coefficients Ai,k are subjected to successive transformation by a wavelet filter at high frequencies ( 4. i ) and by a wavelet filter at low frequencies ( 5. i ) and binary decimation ( 6. i ), until the last level N is reached; filtering ( 7 ) of the output approximating A N ,k and detailing Di,k wavelet coefficients up to preselected ones, according to the type of inspected object; comparison of the filtered approximating and/or detailing wavelet coefficients in their capacity of recognition attributes with preselected respective reference coefficients by classifying device ( 8 ), by a preselected image recognition method, where after, according to the comparison result, the presence and type is determined and/or the studied characteristics of the inspected object is determined.