Method for Estimating the Self-Noise of the Measuring Channel on the Example of the SM-3KV Short-Period Seismometer

Abstract

A new method for estimating the self-noise of the measuring channel of a seismometer is proposed, taking into account the linear relationship between the signal and noise. The method extracts noise using records of two identical measuring channels on the example of the SM-3KV short-period seismometer with an operating frequency range of 0.5–40 Hz. The method was tested on model signals for channel noise with a normal distribution, as well as microseismic noise records recorded on a pedestal by seismometers with locked and free inertial masses. Work with the model signals demonstrated that the accuracy of the numerical result when assessing the level of isolated noise depends on the value of the cross-correlation of the initial seismograms. Consideration of this dependence when calculating the self-noise of real measuring channels yields a noise level similar to the standard method based on separation of the incoherent component of the initial signals. The noise values in the 0.5–40 Hz range with a locked mass of the seismometer are 2.1 ± 0.3 nm/s according to the standard method and 2.2 ± 0.4 nm/s according to the new methods. The obtained values do not contradict the manufacturer’s data of the SM-3KV seismometer, which state that the self-noise level does not exceed 2 nm/s in the operating frequency range.