Guralp Systems CMG-3TB - Manual (Page 21)

Operator's guide
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You can set the range of the meter with the RANGE switch.
When switched to 10 V, the meter ranges from –10 to +10 V (as
marked.) When switched to 1 V, the range is –1 to +1 V.
Calibration and control
You can calibrate a 3TB sensor through the HCU by connecting a
signal generator across the yellow and green CALIBRATION SIGNAL
inputs and turning the CAL ENABLE dial to the component you wish
to calibrate. The sensor's response can now be monitored or recorded,
and calibration calculations carried out.
The section of the HCU below the calibration lines controls the
instrument's mass control system. To initiate locking, unlocking, or
centring, hold down the
ENABLE switch on the HCU together with the
appropriate switch for the command you want to issue for at least six
seconds.
Banana plugs
The remainder of the HCU provides useful connections for each of the
signal lines from the instrument, for attaching to your own equipment
as necessary.
The inclinometer monitor unit
The borehole sensor system can operate successfully in boreholes with
a tilt angle up to 3.5 °. To check that the instrument is installed
suitably close to the vertical, a two-axis inclinometer is installed
within the sensor housing. The inclinometer monitor unit is used as a
visual guide to the sensor's tilt only, and should not be used if precise
attitude information is required. You should check the inclination of
the instrument before unlocking the sensor masses, since too great a
tilt can damage the components.
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