Guralp Systems Scream - Manual (Page 80)

Scream! 4.5
With this configuration uploaded, Tap 3 will continue to produce
output at all times, but Tap 2 will also emit data whenever the trigger
criteria are met. The Triggering button is now shown in red to remind
you that the trigger is active.
Every ticked box in this window will give rise to a data stream coming
from the digitiser, which will be displayed in Scream!'s main window
when Scream! first receives some data from it.
7.3 Triggering
In its standard configuration, the digitiser outputs continuous data at a
sample rate you specify. In addition to this, Güralp digitisers can run
a triggering algorithm on the data they acquire. This allows you to
record data continuously at a relatively low sample rate, but record at
a much higher sample rate during short periods when the trigger is
active. The parameters controlling the triggering algorithm, and
controlling the data output once the system is triggered, are all
selectable by the user, permitting maximum flexibility of operation
and the most efficient use of available storage space.
The digitiser can be set up for triggered output, that is, to generate
certain data streams only when a particular trigger criterion is met.
The trigger criterion can be tested with data from the same or some
other stream. For example, you could use a later tap (with a lower
sample rate) as a trigger for output from an earlier, more detailed tap.
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