Improving the Performance of a Geophone Through Capacitive Position Sensing and Feedback

Abstract

Abstract This paper reports on the improved performance of a geo-phone obtained by measuring the displacement of its proof mass capacitively rather than inductively and operating the sensor as a closed loop system. A measurement of the displacement of the proof mass rather than the velocity measurement made with a conventional geophone provides better low frequency performance. As a result, a geophone can be considered for use in a broader array of applications. A capacitive geophone can operate in either an open loop or closed loop mode. This paper describes a closed loop geophone system with a frequency response similar to the state of the art Streckeisen seismometers.