Precise Test Methods of 2nd Order Transfer Function for Ultra Broadband and Very Broadband Seismometer

The methods of testing the 2nd order transfer function of ultra broadband and very broadband seismometer from acceleration and velocity output are introduced;the test mothod of time-domain response of velocity output is discussed;and the principle of low-frequency response deseparature method is analyzed in detail.The results show that the test methods have degraded computation difficulties in course of calibration and raised efficiency and precision of calibration.