ИСТИНА

The SDA (Spectral Dynamics Analysis) method was applied for the detection and identification of two mixtures of explosive (Hexogen-Trinitrotoluene-Penthryte and Hexogen-Trinitrotoluene-Octogen) hidden under various coverings - the thin, rough, thick layers of Polyethylene foils and a layer of cotton. The main difficulty for identification consists in fact that the mixtures have practically identical spectral properties both in the Stand-Off (reflection nearly at 90°) and Specular (reflection at 45°) mode. The presence of covering makes additional difficulties for identification because it distorts the spectral properties of the reflected THz signal. Nevertheless, it is possible to find the identifiers characterizing the presence of the individual explosive in the mixtures under the covering analyzing the spectrograms and dynamics of spectral lines of the main pulses and the sub-pulses following the main pulse.