Guralp Systems CMG-DM24 - Manual (Page 38)

Operator’s Guide DM-24 Digitiser
Issue G January 2003 36
PROGRAMMING TRIGGER PARAMETERS
Command Syntax Comments
BANDPASS tap# filter BANDPASS
Example: 1 5 BANDPASS
This command will select
data from tap 1 (maximum
sampling rate 100 Hz) and
bandpass filter 5
Bandpass filter parameters
Filter Limits*
0 0% - 100%
1 10% - 90%
2 20% - 90%
5 50% - 90%
* Given in percentage of
the Nyquist frequency.
STA n1 n2 n3 STA
Example: 1 1 2 STA
Calculate short term
averages for 1 s of the Z
component, 1 s of the N/S
component and 2 s of the
E/W component.
LTA n1 n2 n3 LTA
Example: 15 20 20 LTA
Calculate long term
averages for 15 s of the Z
component, 20 s of the
N/S component and 20 s
of the E/W component.
RATIOS n1 n2 n3 RATIOS
Example: 4 6 10 RATIOS
Declare a trigger if the
STA/LTA ratio is 4 for the
Z component OR if it is 6
for the N/S component OR
10 for the E/W
component.
PRE-TRIG n PRE-TRIG
Example: 20 PRE-TRIG
n is in seconds.
When a trigger is declared,
include 20 s of data prior
to the trigger time.
POST-TRIG n POST-TRIG
Example: 60 POST-TRIG
n is in seconds.
When a trigger is declared,
include 60 s of data after
the trigger ends.