Guralp Systems CMG-DCM - Manual (Page 113)

Operator's guide
7.5 Sensor mass control
There are three commands which can be relayed to an instrument
through the DCM to control the position of its sensor mass. For each
instrument the buttons which perform these commands (Centre
instrument
, Lock instrument, and Unlock instrument) can be found at
the bottom of the Digitizer Setup page. The type of sensor you have
installed determines which, if any, of these commands have any effect.
•
The CMG-40T sensor type has no mass lock or centring
capabilities, so all three buttons are inactive.
•
The CMG-3ESP sensor type has manual mass lock and remote
centring, so only the Centre instrument button is active.
•
The CMG-3T sensor type is an automated analogue instrument,
with all three commands available.
•
The CMG-3TD sensor type is a fully digital borehole instrument,
with all three commands available.
Lock and Unlock instrument are provided so that you can secure the
seismometer's sensor mass for safe transportation. Once installed and
unlocked, you should Centre instrument to move the mass to the
correct position to start measuring data. During the execution of any of
these commands, the system will display the three components of the
mass's current position and update them once per second per
component. When the masses are correctly centered all three readings
should be less than ±1,000 counts. Locking or unlocking the sensor
mass typically takes several minutes to complete.
December 2006 113