Noise Type Possible Cause
The mass positions are large,
but slowly trending towards zero,
and one or more of the main
velocity outputs has an offset on
the order of several volts.
The Trillium Compact is powered and not level.
When a Trillium Compact is left powered while not level, it can
take as long as a few hours for the unit to recover after leveling.
More importantly, when in this state, the unit is unresponsive to
ground motion. For short-term deployments or when
immediate confirmation that the sensor is working properly is
required, briefly setting the seismometer in shortperiod mode
allows the unit to recover immediately and produce ground-
motion recordings.
For fast recovery after leveling do one of the following
l Leave the sensor un-powered until after it is level
l Power cycle the unit, which momentarily puts the unit in
short-period mode during start up
l Access the user interface, put the unit into short-period
mode, and then immediately return it to long-period mode
(see "Control Lines" on page65)
l Use the control lines on the digitizer to briefly put the unit
into short-period mode, and then return it to long-period
mode
Table 4-2 - Types of noise and possible causes for vault deployments (Continued)
Chapter 4 - Post-Installation Activities
16889R10 • 2020-11-12 Page 51
To Next Page