Guralp Systems CMG-3T - Manual (Page 36)

CMG-3T
The signal voltages output by the 3T are proportional to ground
velocity and are transmitted from the instrument on balanced
differential lines. In addition, mass position signals are sent as single-
ended circuits referred to analogue ground on the output plug. The 3T
also receives control signals, which are used to clamp and un-clamp
the masses and to run the motors which level and centre the
instrument once in position. Finally, a line is provided for you to
apply a calibrating voltage to the force transducers, thereby measuring
the deflection sensitivity.
5.2 The control system
The internal operations of the 3T are supervised by a control
microprocessor, which drives the mass clamping and centring
36 Issue N