An Effective Method for Improving Low-Frequency Response of Geophone.

Area of Science:

• Geophysics
• Sensor Technology
• Electrical Engineering

Background:

• Traditional moving coil geophones have limited low-frequency measurement capabilities due to their natural frequency and damping ratio.
• Sensitivity variations across the frequency range affect the accuracy of geophone measurements.

Purpose of the Study:

• To analyze the dynamics of geophones and propose a method for extending their low-frequency response.
• To improve the flatness of amplitude and frequency curves and reduce noise levels.

Main Methods:

• Modeling the dynamics of geophones and analyzing their structure and working principles.
• Synthesizing negative resistance and zero-pole compensation methods.
• Implementing a series filter and subtraction circuit to enhance the damping ratio and low-frequency response.

Main Results:

• The proposed method, applied to the JF-20DX geophone, achieved a flat acceleration response from 1 to 100 Hz.
• PSpice simulations and actual measurements demonstrated a significantly lower noise level compared to traditional methods.
• The new method achieved a 17.52 dB higher signal-to-noise ratio at 10 Hz compared to the zero-pole method.

Conclusions:

• The developed method offers a simple circuit structure with reduced circuit noise for low-frequency extension of moving coil geophones.
• This approach provides a viable solution for enhancing the low-frequency performance of geophones.
• The technique yields a flat response and improved signal-to-noise ratio, crucial for accurate seismic and vibration measurements.