Using Scream!
5.1.7 Pre-trigger and post-trigger recording
In order to capture all of a seismic event, it is often useful to be able to record data
immediately preceding the trigger. Güralp digitisers have an internal buffer of some
seconds which allows these data to be added to the triggered stream. Pre-trigger
data are particularly useful for emergent-type signals, where the system does not
trigger until one phase after the first arrival. In addition, to ensure that the coda of
each event is included, some seconds of data are recorded after the system
detriggers.
The two boxes at bottom right of the
Triggering
pane allow the user to set the pre-
trigger and post-trigger data intervals, in seconds. These values determine the
minimum
length of time during which data will be saved before the trigger condition
occurs, and after it has lapsed. Regardless of the intervals chosen, the data in the
triggered streams will begin on a whole second boundary.
5.1.8 Mux Channels
Güralp digitisers provide a range of slow-rate auxiliary channels for reporting the
system's state of health and other diagnostic information, known as multiplexed
(“Mux”) channels. The number of Mux channels depends on the model and
configuration of your digitiser. Generally, three channels are used to report the
sensor mass position, and another measures the internal temperature of the
digitiser. In addition to these, up to 12 Mux channels may be supplied for the user's
own purposes. Some digitisers have a separate
AUXILIARY
port which can be used
to access these channels.
The collection and transmission of Mux channels is controlled using the
Mux
Channels
pane:
47
Issue U - December, 2021
