Research on the Vibration Influence of Cam-Driven Absolute Gravimeter via Parameter Optimization VMD-WVD Method

When the cam-driven absolute gravimeter is used for absolute gravity measurements, the displacement generated by the vibration of the retroreflector couples into the laser interference fringe signal. It severely affects the accuracy of absolute gravity measurements. Therefore, a time-frequency analysis method based on parametric optimization variational mode decomposition-Wigna Ville distribution is proposed. The vibration signals of the measured reference retroreflector are decomposed adaptively to obtain the vibration signals of each frequency band, and studied from the perspective of time-frequency spectrum. At the same time, the impact of vibrations at different frequency bands on the accuracy of gravimetry measurement is analyzed. The experimental results indicate that this method can ensure the time-frequency concentration effect of the Wigner-Ville distribution and improve the accuracy of time-frequency analysis of the measured signals. The influence of vibrations in different frequency bands on the accuracy of absolute gravity measurement was accurately obtained through quadratic fitting. Among them, the impact levels reaching mGal level are as follows: the impact of the 20~40 Hz frequency band is 0.924 mGal, and the impact of the 40~60 Hz frequency band is 1.49 mGal. The vibration in other frequency bands has relatively little influence on the accuracy of gravimetry. The research findings in this paper can provide certain references and guidance for vibration compensation in cam-driven absolute gravimeters.