Improving the Classical Geophone Sensor Element by Digital Correction

Geophones are highly sensitive motion transducers that have been used by seismologists and geophysicists for decades. The conventional geophone's ratio of cost to performance, including noise, linearity and dynamic range is unmatched by advanced modern accelerometers. However, the problem of this sensor is that it measures velocity, and that the linear frequency range is limited to frequencies above the natural frequency, typically at 4-12 Hz. It is shown in this paper how the sensor signal can be digitally linearized 2 decades below the natural frequency obtaining a sensor that allows the user to measure displacement, velocity or acceleration with high sensitivity and large dynamic range.