Gravity data were acquired using a LaCoste& Romberg model G (LCR G-65) relative spring gravimeter (Fig.
Gravity data were acquired using a relative spring gravimeter; uncertainty of 0.06 mGal was achieved.
Calibration results of different type spring gravimeters from the repeated measurements of Estonian calibration lines.
For evaluation purposes, we have carried out relative gravity measurement with the relative spring gravimeter
LaCoste&Romberg model G on 8 stations of the network.
From 1970 to 1990 four gravity campaigns were carried out on the network by using a precise USSR manufactured spring gravimeter GAG-2.
Spring gravimeters and most likely an air transport were used for the connection measurements.
It was based on the determinations of absolute gravity values with a JILAg-5 gravimeter in 1995 as well as relative gravity connections with LCR (LaCoste&Romberg) G-type spring gravimeters. It should be noted that the gravity network of 1999 was more or less consistent with the current realization of the gravity system.
Following this, advances included the (a-stable) relative spring gravimeters
, free-fall measurements made by dropping macroscopic objects and using the methods of geometrical optics to sense motion, and finally, free-fall measurements made using optical interferometry.
* type and characteristic of the specific instrument (quartz systems have larger drifts than metal spring gravimeters),
Thermostat is an essential precondition for the precise measurement with the relative spring gravimeters. There are some methods to find some relation between gravity changes and temperature changes but the expression is too complicated and without satisfactory results till now.