The Effect Of Geophone Specifications On Vector Fidelity

A theoretical model was developed to quantify the intrinsic vector fidelity of a geophone. Results from the model were compared with actual test data which was acquired on a low distortion shake-table. A special test fixture was designed containing 30 conventional geophones: 24 geophones positioned horizontally at 30 degree azimuthal increments and 6 geophones oriented vertically. This Multi Azimuth Test Jig (MATJ) was then positioned on a horizontal low distortion shake-table in various rotated and tilted positions. The response of all of the geophones to a swept sine wave input was recorded using a conventional seismic recording system. The table acceleration and the pilot sweep signal were recorded on auxiliary channels as reference signals. Both time domain and frequency domain analysis were performed on the recorded data. Results show a good comparison between our theoretical model of geophone vector fidelity and the measured data.