Research on Magnetoelectric Seismometer's Low Frequency Extension Technology

Abstract

Magnetoelectric seismometer has many outstanding features, such as low cost, small size, light weight, high sensitivity, low noise, good high frequency response, and reliable operation, simple set up, so these type of seismometer is widely used in several areas. However, because the structure of magnetoelectric seismometer (inertial mass and elastic support module), there has the material and mechanical structure limitation, so the inherent frequency is around between 5 to 30Hz, hard to be lower, hence, the low frequency characteristic is poor. To extend the seismometer's range of application, post compensation is needed. The researchers from both home and aboard proposed many different method to deal with the low frequency response of this seismometer, such as “inverse filter” method, “Lippmann” method, which uses negative resistance and feedback coil. These methods have got some results separately. In this paper, we will propose a low frequency integral method to extend the seismometer's frequency response. It is accomplished through balanced integration and high precision chips to suppress the circuit drifting and noise interference. The results from vibration table shows, after integration, the seismometer's low frequency corner frequency is extended from 2 Hz to under 0.1 Hz, the sensitivity is enhanced from 200V/m·s-1to 400V/m·s-1.