Improving the Performance of a Geophone Through Capacitive Position Sensing and Feedback

Barzilai, A.M.; VanZandt, T. R.; Kenny, Tom

doi:10.1115/imece1998-0311

Cited by 9 publications

(5 citation statements)

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“…Second, variations in the excitation signals highlighted the non-linear behavior of the RS3D, with lower values of the FRF obtained with higher rms input velocity and differences as large as 0.6 dB observed in the −3 dB band. We think that this behavior is due to the mechanical characteristics of spring-mass system of the passive geophone sensor, as stated previously and in other studies (Barzilai et al, 1998;Oome et al, 2009;Stoll, 2015). On the contrary, the NT20s reveal nearly flat FRFs in the tested bandwidth for all the excitation amplitude levels (Figure 4b), in accordance with the specifications that indicate high-frequency response within 1 dB of nominal up to 45 Hz.…”

Section: Laboratory Testssupporting

confidence: 87%

Lab and Field Tests of a Low‐Cost 3‐Component Seismometer for Shallow Passive Seismic Applications

Arosio,

Aguzzoli,

Zanzi

et al. 2023

Earth and Space Science

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We performed laboratory tests and field surveys to evaluate the performance of a low‐cost 3‐component seismometer, consisting of three passive electromagnetic spring‐mass sensors, whose 4.5 Hz natural frequency is extended down to 0.5 Hz thanks to hyper damping. Both lab and field datasets show that the −3 dB band of the seismometer ranges approximately from 0.7 to 39 Hz, in agreement with the nominal specifications. Median magnitude frequency response curves obtained from processing field data indicate that lower corner of the −3 dB band could be extended down to 0.55 Hz and the nominal sensitivity may be overestimated. Lab results confirm the non‐linear behavior of the passive spring‐mass sensor expected for high‐level input signals (a few to tens of mm/s) and field data confirm relative timing accuracy is ±10 ms (1 sample). We found that absolute timing of data collected with USB GPS antennas can be affected by lag as large as +0.5 s. By testing two identical units, we noticed that there could be differences around 0.5 dB (i.e., about 6%) between the components of the same unit as well as between the same component of the two units. Considering shallow passive seismic applications and mainly focusing on unstable slope monitoring, our findings show that the tested seismometer is able to identify resonance frequencies of unstable rock pillars and to generate interferograms that can be processed to estimate subsurface velocity variations.

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Section: Laboratory Testssupporting

confidence: 87%

Lab and Field Tests of a Low‐Cost 3‐Component Seismometer for Shallow Passive Seismic Applications

Arosio,

Aguzzoli,

Zanzi

et al. 2023

Earth and Space Science

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“…On the other hand, if the vibration of the geophone can be directly measured using the proposed interferometry technique, a more detailed vibration measurement at the sensor without a power supply can be realized in comparison with that achieved in the previous study, in which the displacement in the spring-suspended mass vibration in the geophone was measured as a change in capacitance by using the electric signal. 35,36) By using the phase-shifted optical pulse interferometry proposed in this paper, the signal levels of reference light, R, measurement light, S, and interference light, I, can be simultaneously measured to remove the loss in the light-signal path, enabling application in long-distance transmission. Furthermore, by delaying the light-receiving interval of the pulse for each sensor, multiple channel measurements by the same pulse become possible.…”

Section: Discussionmentioning

confidence: 99%

Real-time displacement measurement system using phase-shifted optical pulse interferometry: Application to a seismic observation system

Yoshida¹,

Hirayama²,

Takahara³

et al. 2016

Jpn. J. Appl. Phys.

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We developed a method of detecting incident light levels on the oscillator surfaces and light pulses that include two interfering pulses with a phase shift of π/2 (phase-shifted optical pulse interferometry). This system enables the measurement of displacements greatly exceeding the half wavelength of the laser. Moreover, it allows measurements at multiple locations with a single optical fiber for using optical pulses. In this study, we conducted an interference experiment using 30 ns optical pulses and transmitted them at 1 µs intervals. We confirmed that the above two measurements are possible. Furthermore, from the data of the oscillator used for verification, we showed that measurements on the order of nanometers are possible. Since this method does not require a power supply to the oscillator, its widespread applications in physical exploration can be expected.

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“…Efforts have been made to physically extend the measurement bandwidth of geophones. Pazos et al [ 23 ] employed a capacitor in series with the shunt resistance, Oome et al [ 24 ] applied a passive magnetic spring, and Barzilai et al [ 25 ] operated the geophone as a closed-loop system. Beker et al [ 26 , 27 , 28 ] employed sensor fusion strategies to construct a superior sensor.…”

Section: Introductionmentioning

confidence: 99%

An Effective Method for Improving Low-Frequency Response of Geophone

et al. 2023

Sensors

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The natural frequency of traditional velocity sensors such as moving coil geophones limits their measurable low-frequency range, and the damping ratio affects the flatness of the sensor in the amplitude and frequency curves, resulting in variations in sensitivity over the available frequency range. In this paper, the structure and working principle of the geophone are analyzed and its dynamics are modeled. After synthesizing the negative resistance method and zero-pole compensation, two commonly adopted low-frequency extension methods, a method for improving low-frequency response, which is a series filter and a subtraction circuit to increase the damping ratio, is proposed. Applying this method to improve the low-frequency response of the JF-20DX geophone, which has a natural frequency of 10 Hz, results in a flat response to acceleration in the frequency range from 1 to 100 Hz. Both the PSpice simulation and actual measurement show a much lower noise level via the new method. Testing the vibration at 10 Hz, the new method has a 17.52 dB higher signal-to-noise ratio than the traditional zero-pole method. Both theoretical analysis and actual measurement results show that this method has a simple circuit structure, introduces less circuit noise, and has a low-frequency response improvement effect, which provides an approach for the low-frequency extension of moving coil geophones.

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Improving the Performance of a Geophone Through Capacitive Position Sensing and Feedback

Cited by 9 publications

References 0 publications

Lab and Field Tests of a Low‐Cost 3‐Component Seismometer for Shallow Passive Seismic Applications

Lab and Field Tests of a Low‐Cost 3‐Component Seismometer for Shallow Passive Seismic Applications

Real-time displacement measurement system using phase-shifted optical pulse interferometry: Application to a seismic observation system

An Effective Method for Improving Low-Frequency Response of Geophone

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