Striletskyi Y. Signal Processing Methods and Means in Spectral Impedance Investigation of Industrial Systems Elements

The thesis launched new and developed already known theoretical and methodological principles in the field of digital signal processing in computerized systems of non-destructive testing, including components of spectral analysis of sampled data arrays, components of noise-proof excitation signal generation and their processing in the information-measuring channels necessary for propagation a generalization approach to the creation of new means of non-destructive control of industrial objects. Presentation of response signal from physical object in form of a regression model was used for designing the method of determining parameters of spectral component in the noisy signal by recursive analysis of interaction of extraneous spectral components with a synchronous pair of harmonic excitation signals. Signal description in form of regression model constructed using the values of the sampled signal obtained during free vibrations of physical objects was used to reproduce the time variations of the amplitude of the individual spectral components and to increase the informativeness of signal representation which is necessary for the investigation of mechanical properties of objects. Based on the proposed methodical approaches technical solutions are realized in the form of special processors that make it possible to create specialized information-measuring systems of non-destructive control with greater informativity. The special processors are designed for signal processing for reproducing the shape of noise-distorted signal and its synchronous demodulation, the search for small phase angles of noisy signals, digital synthesis of the harmonic waveform and its subsequent transformation in order to improve spectral purity and for processing of periodic signals obtained from thermal field transformation into an electrical signal. Thus, a methodological and hardware basis for the use of spectral evaluation of the properties of industrial objects in the tasks of non-destructive control was created.