CALIBRATION OF HIGHER FREQUENCY CHARACTERISTICS OF GEOPHONE

Abstract

In this paper the author developed the new method to calibrate the geophone characteristics in the higher frequency range, where exact measurement can not be assured by all most all methods developed in usual lower frequency range. When the longitudinal wave propagates along one dimensional bar, we can evaluate its particle velocity by detecting its strain. Using this principle, we detect the vibration velocity of the geophone body (to be, tested) attached to the end of the bar. The merit of this method is that we can check the setting condition of the geophone by evaluating the reflection coefficient of the wave at the geophone end. By this method the author could calibrate the frequency characteristics of geophones up to 3000 or 4000 cps.