Guralp Systems CMG-DCM build <10,000 - Manual (Page 175)

Operator's Guide
The second section of this web page deals with calibration. Note that
all entered values must be integers so, for example, if you wish to
calibrate with a 0.5Hz sine-wave, this should be entered as a 2 second
period. Please refer to the relevant manuals for your digitiser and
sensor for more details of these options.
The screen looks like this (shown in sections):
The Amplitude value refers to an arbitrary full-scale output from the
calibration circuitry. It can be left at 100% unless clipping is
observed, in which case it should be reduced until an undistorted
output is observed.
The square wave (step) and random calibration dialogues are similar:
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