Mathematical modeling of geophone magnetic ring for sensitivity studies


  • Mawa Patrick Luka Universiti Teknologi PETRONAS
  • Ser Lee Loh Universiti Teknikal Melaka
  • Dennis Ling Chuan Ching Universiti Teknologi PETRONAS



Sensitivity, resistivity, magnetic field


Geophone (model SM-24) pertaining its performance to detect surface wave at Free Wave Generator is analyzed. Sensitivity studies have been conducted to model the physical disadvantage such as spring suspension and magnetic field in geophone. From mathematical model of the ring permanent magnet, applying “superposition” has suggested a solution: an external resistor across its output terminal to amplify the exhibited linear damping behavior. Geophone with 60%, and 75% damping ratio are designed and built and the results show that 75% damping provide highest sensitivity. Analytic expression of vertical component of magnetic field shows that the damping ratio can be increased physically by increasing the radius of the magnetic field, however, by modifying the SM-24 damping ratio, similar outcome can be obtained.


Robertson, W. (2003). Design of a non-contact magnetic spring for vibration isolation. The University of Adelaide, Australia: Research proposal.

Barzilai, A. (2000). Improving a geophone to produce an affordable, broadband seismometer. Stanford University: PhD Thesis.

Braunbek, W. V. (1939). Fresichwebende Korper im elektrischen und magnetisachen feld. Tubingen.

Cathey, J. J. (2001). Electric Machines. McGraw-Hill.

Cedrat Groupe. Accessed in 2008 from

Delamare, J., Yonnet, J. P. and Rulliere, E. (1994). A compact magnetic suspension with only one axis control. IEEE Trans. Magn. 30 (6).

Earnshaw, S. (1842). On the nature of the molecular force which regulate the constitution of the luminferous ether. Trans. Cambr. Philos. Soc.797-112.

Filatov, A. V. and Maslen, E. H. (2001). Passive magnetic bearing for flywheel energy storage systems. IEEE Trans. Magn. 37 (6).

Florian, E. F., Haggard, S. E. and Riley, T.E. (1979). Geohone with shaped magnetic field. Marks Product Incorporated: UK Patent Application, UK 2022359.

Furlani, E. P. (2001). Permanent magnet and electromechanical devices. Academic Press.

Geospace. Accessed in 2008 from

Hol, S. A. J. Design and Optimization of a magnetic gravity compensator. Eindhoven University of Technology: Ph.D. Thesis. 155-157.

ION Sensor. Accessed in 2008 from

Jones, W. (1980). Earnshaws theorem and the stability of matter. Eur. J. Phys. 85-88.

Magnetic, accessed in 2008.

Nagaya, K. and Ishikawa, M. (1995). A noncontact permanent magnet levitation table with electromagnetic control and its vibration isolation method using direct disturbance canellation combining optimal regulators. IEEE Trans. Magn. 31 (1).

Oome, A. J. J. A., Janssen, J. L. G., Encica, L., Lomonova, E., and Dams, J. A. A. T. (2009). Modeling of an electromagnetic geophone with passive magnetic spring. Sensors and Actuators A: Physical 153(2). 142-154.

Palm, W. J. and Modeling. (1999). Analysis and control of dynamic systems. John Wiley and Sons Inc.: Second edition.

Ravaud, R., Lemarquand, G., Lemarquand, V., and Depollier, C. (2008). Analytical calculation of the magnetic field created by permanent-magnet rings. IEEE Trans.Magn.44 (8). 1982–1989.

Recdeker, M. (1984). Geophone. Mobil Oil Corporation: US Patent Application, US 4,597,070.