Table of Contents
Advertisement
Level Triggering
By default each Level trigger process is OFF, but simply toggle this using the Right button.
Level Triggering
Enable: On
> Sensor: 3D
Set Trigger Level
% of Full Scale
5.00 %
0.10316 g
MMI: VI
PEIS:
STA/LTA Triggering
By default the STA/LTA trigger process is OFF. Toggle this ON/OFF using the Right button.
STA/LTA Triggering
Enable: Off
> Threshold
STA window
LTA window
Filters: 2-20Hz
Channel: 3D
average signal level, you set the Threshold to 3. The length of the short and long term
time windows is also user selectable. The LTA value must be larger than the STA value.
Signal averages can be calculated using the raw data or filtered to suit to local earthquake
detection. On the Filters line, use the Right button to toggle the 2-20Hz filter on or off.
The STA/LTA algorithm can run on one of the triaxial channels (Z, N or E), on the 1D
channel, or on all of the 3D input channels. Toggle the Channel using the Right button.
The Gecko can trigger on the vector sum of the 3D sensor
channels, or from the 1D sensor channel. The percentage
level of the trigger threshold will affect the ground motion
units displayed on the Set Trigger Level screen. For
accelerometers, the estimated MMI and PEIS intensity that
relates to this trigger threshold will also be displayed.
Use the Up/Down buttons to change the number values
from 0.01% to 99.99% of the recorder's full scale range. The
line below will update with the ground motion value based on
6
the calibrated sensor sensitivity and gain of your Gecko.
The Short Term Average (STA) signal level divided by the
Long Term Average (LTA)
signal level produces a ratio
indicating how much above-
average signal is occurring.
If you want to declare and event when the short term
average signal level is three times higher than the long term
16
Short Term Average
2.0 seconds
averaging window
A more detailed explanation
of the STA/LTA trigger
algorithm is provided in our
Waves data analysis
application's user manual.
You can visualise the effect
of changing the various
STA/LTA settings using
Waves.
Advertisement
Table of Contents
