Conventional Seismic Geophone Test Method Research

Seismic geophone is a kernel component of field data acquisition of seismograph,because its performance directly affects the performance of the whole seismograph.Its working principle is a device that converts mechanical signals into electrical signals according to Faraday's law of electromagnetic induction,and generates electrical simulation of vertical components of ground motion with maximum fidelity.The purpose of this paper is to comprehensively research the damping coefficient,spurious frequency and parallel resistance of the detector.Based on the internal structure and working principle of the geophone,the motion equation of the geophone is established and the solution is obtained.The natural vibration and forced vibration of the geophone are derived.The calculation results of the geophone damping coefficient,natural frequency and sensitivity are mathematically derived in detail from the perspectives of dynamics and electromagnetism.To analyze the investigation method for geophone damping coefficient so as to achieve some experimental verifications that can show that slight change of the peak voltage of the second peak of the geophone damping coefficient affects the test results.It is known that the measurement equation of geophone's damping coefficient is a second-order underdamping system.Referring to the article "A Method for Measuring Damping Ratio of Underdamping System" by Wang Yong et al.,the method of measuring geophone's damping coefficient by using the ratio of the area of the first period and the second period of the attenuation waveform is derived mathematically.Combined with experimental data,it is proved that this method can also be used to calculate geophone's damping coefficient.Compared with the first peak voltage ratio and the second peak voltage ratio,it has better anti-interference capability.For the false frequency of geophone,when using horizontal shaking table test,an inclination sensor can be added to observe the offset angle of spring vibrator inside the geophone to prove the feasibility of the method.Different types of geophones are selected to change the resistance value of parallel resistors,and the influence of parallel resistors on the test results of geophone related parameters is verified through experiments.