Guralp Systems CMG-DM24 - Manual (Page 48)

CMG-DM24
You can specify step calibration by selecting the Square wave button.
The square wave consists of a positive step at the start of the next
minute of the digitizer’s internal clock, followed by a negative step
after a specified number of minutes. After a further delay of the same
number of minutes, the calibration signal is disconnected. The default
is 2 minutes. The Period and Frequency settings are ignored.
The Broadband Noise calibration signal consists of a constant stream
of white noise, which lasts for the specified number of minutes. The
Period and Frequency settings are ignored.
Mass Control
Many Güralp instruments respond to control signals to centre, unlock,
and lock the sensor masses. These signals are generated by the
digitizer. You can tell the digitizer to send a signal using the Center
Now, Lock Now and Unlock Now buttons on the Mass Control tab.
If you select Monitor progress, the window will remain open during
the process, and the mass positions will be displayed in the Vertical,
N/South and E/West boxes. If you leave Monitor progress unselected,
the window will close. You can still monitor mass positions by
selecting the appropriate streams and opening a WaveView window for
them.
Depending on which Sensor Type you have chosen in the System tab
(see above), not all the control signals will be available. For example, a
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