Reducing the Time Consumption of Vibration Correction Methods for Absolute Gravimeters

Abstract

Free-fall absolute gravimeters are widely employed to measure the gravitational acceleration, commonly known as g. It applies an interferometer to measure the trajectory of a free-falling object. The measurement precision of the absolute gravimeters is limited by the ground vibration. A vibration correction method is often applied in a noisy environment including a moving platform, sometimes it is required to get the g value quickly. It takes much time about 6 min to calculate the g value for one set measurement (no less than 25 drops). In order to quickly and accurately obtain the g value in hostile environments, there are two modifying methods including applying a lower sampling rate than original sampling rate of the vibration signal, and applying a division on trajectory data method. An equally spaced in distance division method is used. The results show, when applying the sampling rate of the vibration signal 1 MHz and the division factor 14, the total consumption time is reduced to one quarter of the time, from about 6 min to 1.5 min. Meanwhile, the error between the corrected results with and without the modifying methods is below 10 μGal, and the standard deviation of the g value has no significant change. In the future, promisingly it will be used to quick and precise dynamic absolute gravity measurement in hostile environments.