Guralp Systems CMG-CD24 - Manual (Page 29)

Operator's Guide
criteria are met. The Triggering button is now shown in red to remind
you that the trigger is active.
Every checked 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. Every stream
is identified by a 6-character code, where the first four characters
identify the digitiser, and the last two characters identify the
individual stream. The first four characters are set by default to the
serial number of the digitiser; you can change this on the System ID
pane (see page 26) or from the digitiser's console.
3.1.3 Triggering
In its standard configuration, the CD24 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 CD24 can be set up for triggered output, that is, to output 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. Scream!
4 (and above) also allows you to configure each digitiser to receive
triggers from other digitisers.
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