Guralp Systems CMG-DM24 - Manual (Page 12)

CMG-DM24
All of these configuration options are easily changed via Scream!, or
you can use the terminal commands SET-TAPS and CONTINUOUS.
Triggering
The DM24 has a flexible triggering system. When the digitizer triggers,
it can optionally output (or store – see DUAL mode on page 16)
additional data. Any combination of tap and component can be output
as the result of a trigger.
In the example above, you might configure the sensor to output Tap 2
data (at 10 samples/s) continuously, but when a trigger is declared, to
output Tap 0 data (at 500 samples/s) as well.
Using triggering helps you to use limited storage capacity or
bandwidth more effectively.
The digitizer can look at the data from any tap to decide if a trigger has
occurred, including taps which it does not output. Which tap you
choose depends on the frequencies you want the trigger system to be
most sensitive to.
There are three types of trigger.
•
A LEVEL trigger occurs when the absolute sample values exceed
a configured value.
The commands GTRIGGERS, MICROG, and HIGHPASS control
LEVEL triggering.
•
An STA/LTA trigger occurs when the ratio of a short-term
average to a long-term average for recent data exceeds a
configured value.
The commands TRIGGERS, TRIGGERED, STA, LTA, RATIOS, and
BANDPASS control STA/LTA triggering.
•
A software trigger occurs when you issue the command
S/WTRIGGER.
The DM24 can output data streams for a period of time before the
trigger starts, and after the trigger ends. The commands PRE-TRIG and
POST-TRIG set these time periods.
Triggering options can also be configured through Scream!.
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