The experimental approach (hardware and software) to the study of the elastic anisotropy of rocks on spherical samples under hydrostatic pressure up to 400 MPa is discussed. A substantial innovation of the existing measuring system and processing methods enabled us to make a detailed investigation and evaluation of the kinematic as well as dynamic parameters of elastic waves propagating through anisotropic media. The innovation is based on digital recording of the wave pattern with a high sampling density of both time and amplitude. Several options and results obtained with the innovated laboratory equipment are presented.

One of the fundamental problems in non-destructive testing and geophysics is the precise determination of the first arrival of acoustic emission (AE) signals (or seismic signals) recorded by multi-channel systems. The knowledge of this time is very important, mainly in the case of automatic localization of individual AE events. Several approaches are routinely used in practice such as crossing of the threshold level, analysis of the LTA/STA (long-time average/short-time average), etc. In our paper, an approach based on high-order statistics (HOS) that is able to carry out precise arrival time determination without human intervention is presented. The approach was tested on real AE data recorded by an eight-channel recording system. This simple, accurate and quite fast method is predetermined to be used in automatic processing of transient waveform data from acoustic emission, seismic signals, ultrasonic sounding, etc.

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