Guralp Systems CMG-3ESPCD - Manual (Page 38)

CMG-3ESPCD Digital Broadband Seismometer Calibrating the 3ESPCD
3. Repeat this measurement for several tilt angles.
4. For the vertical sensor, the input acceleration is given by
a = g sin φ
whilst for the horizontal sensor, it is
a = g ( 1 – cos ) φ
Calculate the input acceleration for each of the tilt angles used, and
plot a graph of mass position output against input acceleration.
5. The gradient of the line obtained gives the sensitivity of the coil (in
V/ms -2 , if g was measured in ms -2 and the mass position in V.)
6. The coil constant K is equal to this sensitivity divided by the value of
the displacement feedback resistor, given on the calibration sheet.
MAN-C3E-0002 38 Issue B - November 2013