On the calibration of feedback broadband seismometer FBS-3A with current signal

IntroductionWith the time passing by and the environment changing, the characteristics of the components in a seismometer may change a little to some extent because of some certain reasons. Therefore the reliability of a sensor(s output may lower the reliability and a wrong result may also be produced if these changes are not realized and controlled or adjusted in time. Hence, the seismometers must be calibrated either before leaving factory or in use, so as to check the parameters and the cha…

On the calibration of feedback broadband seismometer FBS-3A with current signal

With the time passing by and the environment changing, the characteristics of the components in a seismometer may change a little to some extent. To realize this kind of change and take steps to control or adjust it is helpful to improve the reliability of the sensor(s output. Therefore, every seismometer must be calibrated, either before leaving factory or in use. Up to now, there are two kinds of calibrations used frequently with current signals, namely using square-wave signal and sine-wave signal. From the view point of systematic analysis, after getting the transfer function of the seismometer and simplifying the process of calibration with current signal, research has been done, in complex frequency domain, to the process of calibration with simulation method. On the basis of this, the relationship between the output figure of square-wave calibration and the intrinsic parameters of a sensor is discussed in this paper. The relationship between the steady output of sine-wave calibration and the calibration current, as well as the relationship of the calibration outputs caused by two sine waves with specific frequencies is presented. As the result of the theoretical analysis, two applications of the calibration with current signal are provided. The aim of this paper is to clarify the meanings of these two commonly used calibration methods, which would be fairly positive and helpful to the adjustment and the practical application of the seismometers.