Spring gravimeter calibration experiment with an inertial acceleration platform

TL;DR

This paper presents an automated calibration system for relative gravimeters using an inertial acceleration platform, demonstrating stable long-term calibration with minimal displacement error and quantifiable scale factor uncertainties.

Contribution

It introduces a microprocessor-controlled calibration system with low-frequency inertial forces and a method to determine platform motion stability, improving gravimeter calibration accuracy.

Findings

G336 scale factor: 8128.647 nm/s2/v with 1.1% uncertainty

G906 scale factor: 9421.017 nm/s2/v with 2.7% fluctuation

Calibration system operated reliably over 7 months

Abstract

This experiment tested an automatically calibrate the relatively gravimeter with an absolute inertial force. The whole calibration system was controlled by microprocessor and low frequency oscillations were generated by a step motor. It could produce different period low frequency sinusoid inertial force. A LVDT (Linear Variable Differential Transformer) sensor was introduced to determine the frequency transfer function and the stability of platform vertical motion. The error of vertical displacement induced by the mechanical part of platform is less than 0.01 mm. Two LCR gravimeters (G336, G906) were settled on the platform. G336 was in the centre of platform and G906 was in the left side. A calibration program has been integrated in the micro processor which could send calibrate signal once a week. During the more than 7 moths experiment, the scale factor of G336 is 8128.647 nm/s2/v with 1.1% uncertainties and G906 is 9421.017 nm/s2/v with 2.7% fluctuations.