Seismic instruments: article

Fast calibration of velocimeter using stated reference
I. Kalinyuk
V. Boyko
F. Pankov
N. Pankov
Vernadsky Crimean Federal University, Simferopol, Russia
Journal: Seismic instruments
Tome: 53
Number: 3
Year: 2017
Pages: 42-54
UDK: 550.34.034
DOI: 10.21455/si2017.3-4.
Keywords: calibration, velocimeter, constant seismometer, digital seismic station
Аnnotation: All digital seismic recorders of the Crimean seismological network are equipped with sensors that are inherited from galvanometric registration. Long-period channels are equipped with SKD sensors, and short-period channels are equipped with SM3, SCM, CX, and C-5-C sensors. The instruments periodically undergo preventive maintenance due to technical deterioration and a long period of operation. At the peripheral stations there are no experts on equipment, all the necessary work on installation, preventive maintenance, adjustment and calibration is performed by specialists from the Institute's hardware and software group during business trips. In this connection, there was an urgent need for operational control of the parameters of the velocimeters and the through measuring and recording channel as a whole. Experience at the peripheral seismic stations and time points of seismic observations, not equipped with shakers, has shown that it is convenient to calibrate short-period seismic channels using a reference calibrated mobile digital seismic station. This station is assembled on the basis of a digital seismic recorder Baikal-8 and a three-component sensor SK1-P. The stated reference (standard) is preliminarily calibrated on a vibrating platform located at the seismic station “Simferopol”. The article describes the calibration of the standard on a shake table, describes various approaches to calculating the main parameters of a velocimeter. The relationship between the main parameters of the velocimeter and the extremum times and zeros of the response function of the velocimeter to the step of displacement is obtained. With the help of these formulas, you can quickly monitor the parameters of the velocimeter even in field conditions. Particularly noteworthy is the idea of calibrating seismometric channels relative to one standard, which can be realized without forced external influences. An original technique for calibrating a digital seismic station using a reference is described, based on an analysis of the ratio of the microseismic background spectra. Using the synchronous recording of the microseismic background and the mathematical optimization package in the OriginLab program, the parameters of the calibrated station were determined. Formulas for calculating the velocimeter parameters by means of a standard are given, which make it possible to determine the complex frequency response of a digital station. Convenience of this method in efficiency, the absence of the need for laboratory conditions for calibration, the use of microseisms and the ability to determine all parameters of the through channel at the same time.