Synthesis of the Optimal Piecewise Linear Sweep Signal for Vibrational Seismic Sounding

A method for calculating the frequency sweep law of a vibration source is proposed and substantiated, which yields a flat spectrum of the correlogram of the target wave, regardless of natural amplitude–frequency distortions introduced by the medium and source. Such a spectrum serves as the main prerequisite for achieving maximum resolution of closely spaced wave pulses in the resulting seismogram. The methodology includes test sounding of a typical seismic geological object with any linear sweep signal in the desired frequency range, separation and spectral analysis of the vibrogram of the target wave, splitting of the resulting spectrum into many narrow frequency intervals, and calculating for each of the intervals its own partial linear sweep. Construction of a continuous sequence of these partial sweeps is the final operation in synthesizing an adaptive nonlinear (piecewise linear) sweep signal. In this study, the necessary conditions are found and formulated that ensure correctness of the coupling procedure for partial sweeps.