Abstract
The transfer function of a moving coil electromagnetic geophone requires up to six constants: the suspended mass, the natural resonant frequency, the mechanical and the electrical damping factors, the inductive time constant of the coil-damping resistance circuit, and the coil transductance. If the mass is known, the remaining constants may be satisfactorily determined by displacing the mass with a known dc current, and observing the time varying output potential on removal of the steady current. The techniques outlined are suited to in situ calibration, and have a minimum equipment requirement of a CRO and a small battery. Improved accuracy is possible using a precision signal generator and a quality CRO, if the geophone natural and upper resonant frequencies are measured by the phase ellipse method. Calibration is possible for both under- and overdamped systems, using either the derived formulas or accompanying graphs. The accuracy attainable is dependent on the geophone damping and frequency range of operation, but is typically 2 percent in absolute amplitude and 2 in phase for 0.7 critical damping.
| Original language | English |
|---|---|
| Pages (from-to) | 208-214 |
| Number of pages | 7 |
| Journal | IEEE Transactions on Geoscience Electronics |
| Volume | 15 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 1977 |
| Externally published | Yes |
Cite this
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Theory and Practice of Geophone Calibration In Situ Using a Modified Step Method. / Asten, Michael W.
In: IEEE Transactions on Geoscience Electronics, Vol. 15, No. 4, 1977, p. 208-214.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Theory and Practice of Geophone Calibration In Situ Using a Modified Step Method
AU - Asten, Michael W.
PY - 1977
Y1 - 1977
N2 - The transfer function of a moving coil electromagnetic geophone requires up to six constants: the suspended mass, the natural resonant frequency, the mechanical and the electrical damping factors, the inductive time constant of the coil-damping resistance circuit, and the coil transductance. If the mass is known, the remaining constants may be satisfactorily determined by displacing the mass with a known dc current, and observing the time varying output potential on removal of the steady current. The techniques outlined are suited to in situ calibration, and have a minimum equipment requirement of a CRO and a small battery. Improved accuracy is possible using a precision signal generator and a quality CRO, if the geophone natural and upper resonant frequencies are measured by the phase ellipse method. Calibration is possible for both under- and overdamped systems, using either the derived formulas or accompanying graphs. The accuracy attainable is dependent on the geophone damping and frequency range of operation, but is typically 2 percent in absolute amplitude and 2 in phase for 0.7 critical damping.
AB - The transfer function of a moving coil electromagnetic geophone requires up to six constants: the suspended mass, the natural resonant frequency, the mechanical and the electrical damping factors, the inductive time constant of the coil-damping resistance circuit, and the coil transductance. If the mass is known, the remaining constants may be satisfactorily determined by displacing the mass with a known dc current, and observing the time varying output potential on removal of the steady current. The techniques outlined are suited to in situ calibration, and have a minimum equipment requirement of a CRO and a small battery. Improved accuracy is possible using a precision signal generator and a quality CRO, if the geophone natural and upper resonant frequencies are measured by the phase ellipse method. Calibration is possible for both under- and overdamped systems, using either the derived formulas or accompanying graphs. The accuracy attainable is dependent on the geophone damping and frequency range of operation, but is typically 2 percent in absolute amplitude and 2 in phase for 0.7 critical damping.
UR - http://www.scopus.com/inward/record.url?scp=0017542121&partnerID=8YFLogxK
U2 - 10.1109/TGE.1977.294494
DO - 10.1109/TGE.1977.294494
M3 - Article
VL - 15
SP - 208
EP - 214
JO - IEEE Transactions on Geoscience Electronics
JF - IEEE Transactions on Geoscience Electronics
SN - 0018-9413
IS - 4
ER -