Guralp Systems CMG-3ESPCD User Manual
Page 79
CMG-3ESPCD Digital Broadband Seismometer
Inside the 3ESPCD
to one or other side. With the horizontal bases tilted, gravity will keep the
masses pressed against their end stops, effectively locking them in place.
Because the 3ESPCD mass assembly is designed for a degree of robustness, no
further locking is required.
The BUSY LED is lit during each stage, but goes out briefly between stages,
allowing you to follow the progress of the lock.
7.1.2.2 UNLOCK
This command unlocks the sensor masses and prepares the instrument to
begin operating. If UNLOCK is activated when the masses are already
unlocked, the processor will lock them and attempt to unlock again. This is
useful if you suspect that the locking procedure has failed.
During the UNLOCK procedure, the instrument automatically performs a round
of centring for each component. Again, you can use the BUSY LED to monitor
the progress of unlocking.
As shown, the process is:
1. The instrument checks to see whether the vertical mass is locked, and
unlocks it if necessary.
2. The vertical mass is centred by applying pulses to the motor. This
stage is often very short, since the vertical mass is locked near its
central position.
3. The instrument checks the N/S sensor and base, and unlocks the
sensor.
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Issue B - November 2013