Seismic instruments: article

METHOD FOR ESTIMATING THE SELF-NOISE OF THE MEASURING CHANNEL ON THE EXAMPLE OF THE SM-3KV SHORT-PERIOD SEISMOMETER
A.N. BESEDINA
N.V. KABYCHENKO
S.G. VOLOSOV
Sadovsky Institute of Geospheres Dynamics of Russian Academy of Sciences
Journal: Seismic instruments
Tome: 57
Number: 3
Year: 2021
Pages: 5-18
UDK: 550.34.03
DOI: 10.21455/si2021.3-1
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Keywords: short-period seismometers, measuring channel, instrumental noise, self-noise, transfer function, microseismic noise
Аnnotation: 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 is based on the extraction of noise using records of two identical measuring channels on the example of a short-period seismometer SM-3KV with an operating frequency range of 0.5-40 Hz. The method was tested on the model signals for channel noises with a normal distribution, as well as on records of the microseismic noise recorded on the pedestal by seismometers with locked and free inertial masses. It was shown on the model signals that the accuracy of the numerical result when assessing the level of the selected noise depends on the value of the cross-correlation of the original seismograms. Consideration of this dependence in the self-noise calculation of the real measuring channels allows obtaining a noise level similar to the standard method, based on the separation of incoherent component of the initial signals. The noise values in the range of 0.5-40 Hz 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 passport data of the SM-3KV seismometer, according to which the self-noise level does not exceed 2 nm/s in the operating frequency range.