Guralp Systems CMG-3ESPCD - Manual (Page 47)

CMG-3ESPCD Digital Broadband Seismometer Using Scream!
For example, setting the STA to 1 second, the LTA to 10 seconds and the Ratio
to 4 would give rise to the following trigger behaviour:
Usually, the values of the STA and LTA periods, and of the Ratio, will be the
same for all selected channels. For convenience, Scream! will automatically
fill in other values to match ones you enter. If you want to use different
values for some channels, you should clear the “Common values” check-box
before altering them.
Once you have enabled the STA/LTA triggering method on a particular
channel, you can use the Control window to change the values of the STA and
MAN-C3E-0002 47 Issue B - November 2013