Chapter 3
Performing a Surface Vault Installation
Trillium Compact User Guide
16889R5
2014-03-04
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3.9 Troubleshooting Your Installation
It is normal to see spikes in the horizontal channels of a Trillium Compact as the seismometer
settles after installation. However, if these spikes do not diminish after a few days, there may
be a problem with the installation and the site should be visited to determine the cause of
the spikes.
lists common types of noise, including horizontal spikes, that may occur and
reasons why the noise may be present.
Table 3-2
Types of noise and possible causes for surface vault deployments
Noise Type
Possible Cause
Spikes on the horizontal channels
The feet of the seismometer are not locked.
There is a force pulling on the cable.
There is something touching the sides of the seismometer.
Continuous low frequency
wander (random noise, larger on
horizontal channels)
Insulation is missing or not well sealed, allowing drafts to
blow over the seismometer.
There are forces, such as wind, acting on the installation.
Spikes on the vertical channel
Usually due to electrical system noise. For example, power
supply noise from a battery charging circuit, or interference
from a strong magnetic or radio source that is nearby.
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
levelling. 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 short-
period mode allows the unit to recover immediately and
produce ground-motion recordings.
For fast recovery after levelling do one of the following
• Leave the sensor un-powered until after it is level
• Power cycle the unit, which momentarily puts the unit
in short-period mode during start up
• Access the user interface, put the unit into short-period
mode, and then immediately return it to long-period
mode (see
Section 7.3 “Seismometer Control”
• Use the control lines on the digitizer to briefly put the
unit into short-period mode, and then return it to long-
period mode
