In the past, designers relied greatly on simplified geophone models to describe the physical quantities of a geophone. Several iterations of fine tuning the geophone variables were required to achieve a desired geophone characteristic. Although many geophone prototypes were built before a geophone design was finalized, it was still impossible to assure an optimum geophone design. An easier, faster, and more accurate method of predicting geophone parameters is described and the method of computer-aided geophone design is outlined. A description of a nonlinear geophone model is presented and a numerical method to compute the nonlinear magnetic flux density distribution is outlined. An integration algorithm is used to compute the geophone sensitivity and open-circuit damping. The measurement of geophone distortion is described, and the harmonic distortion due to nonlinearity of sensitivity and damping is computed. The data of a geophone spring constant were obtained through a recent experiment, and the harmonic distortions caused by the nonlinearity of the spring are computed. Finally, the total harmonic distortion of a geophone is obtained.Programs developed to predict geophone sensitivity, damping, and distortion are described. It is shown that the method used to compute the nonlinear flux density distribution converges properly and the results obtained are meaningful. Three different types of geophones are analyzed and a comparison between the simulated and measured data is made. In all three cases, good correlation exists between the parameters predicted and the parameters actually measured. Information obtained by geophone parameter prediction can be very useful in the geophone design process, in optimizing geophones, and in achieving higher performance levels.

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