ATTENUATION OF THE ENERGY OF MEASUREMENT SIGNALS CAUSED BY DEVIATIONS FROM THE HORIZONTAL OF A GEOPHONE-TYPE TRANSDUCER

Abstract

The article examines the features of measuring-signal formation in geophone transducers and the influence of sensor deviation from the horizontal position on their energy characteristics. The relevance of the study is driven by the wide use of such transducers in low-frequency vibration monitoring systems, where the accuracy of signal parameter estimation strongly depends on proper sensor installation. The research is based on the SM-24 sensor, whose mechanical and electrical parameters are described. Experiments were conducted involving the registration and recording of signals and noise at different geophone tilt angles.

At the first stage of processing the experimental signals, centering and scaling were performed, along with the removal of the DC component and the conversion of digital readings into physical quantities. Statistical characteristics of the signals - mean, mode, median, variance, and standard deviation - are presented, which made it possible to identify a clear tendency toward increasing signal instability with increasing tilt angle. This indicates that the sensor's orientation has a significant impact on measurement quality. Furthermore, the study shows that at tilt angles of 0 - 30°, the energy characteristics remain relatively stable, while in the range of 60 - 90°, the signal energy increases sharply. This effect is associated with changes in the effective stiffness and the behavior of the sensor’s spring–mass system. To analytically describe the dependence of signal energy on the tilt angle, linear, exponential, and polynomial regression models were applied. A comparison of the model accuracies revealed that third-order polynomial regression provides the best fit, showing the highest coefficient of determination (R²) for both signals and noise. The ratio Es/En - a criterion reflecting the ability to distinguish the signal from background noise - was also analyzed. Despite the nonlinear behavior of this parameter, it was established that for all tilt angles, signal energy significantly exceeds noise energy, ensuring reliable extraction of useful information. Therefore, although the geophone transducer retains its ability to register meaningful signals even at considerable tilt angles, optimal sensor performance is achieved when it is positioned as close to the vertical orientation as possible. The obtained results have practical significance for the development of monitoring systems, as they allow modeling the influence of sensor orientation on measurement accuracy and optimizing installation procedures for such transducers.