In this paper, an analysis of the spread of random extraneous low-frequency (50 Hz) vibrations excited in a gravimeter body is presented. Further, their influence on the gravimeter scale reference system is determined by applying the theory of covariance function. The data on the measurement of strength of random extraneous vibrations in fixed points excited in the gravimeter body were recorded on the time scale in the form of arrays using a three-axis accelerometer. High-frequency (2 and 20 kHz) noise vibrations were also used to modulate the gravimeter scale data. While processing the results of measuring the strength of random extraneous vibrations and the data arrays on the reference system, estimates of autocovariance and cross-covariance functions by changing the quantisation interval on the time scale were calculated. Software developed within the MATLAB 7 package was applied for the calculations.