Guralp Systems CMG-1T - Manual (Page 24)

CMG-1T Ocean Bottom Seismometer Operator’s
Guide
Section 5, Page 2 September, 1999,
Issue C
The required method of zeroing the bowl tilt is provided diagrammatically in the
drawing below. The radial and azimuth adjustments are done until the 2 axes
inclinometer outputs are brought as close to zero as possible. The radial offset
tilt magnitude is calculated from the X, Y readings of the inclinometer and the
azimuth position is determined from the sign information of the inclinometers.
Two sets of position sensors fitted to the motor shafts transmit the digital shaft
position signals to a micro-processor to enable precise radial and azimuth
movement without slippage. In fact, the position detectors are absolute and
provide position information without losing information when the system is
switched off.