Guralp Systems CMG-DM24 - Manual (Page 69)

Operator's guide
Data is taken from this tap and passed through a band-pass filter
before it is examined. This filtering maximises sensitivity within the
frequency band of interest whilst filtering out noise outside this band.
The corner frequency of the band-pass filter depends on the values of
tap and filter:
•
filter = 1 creates a filter with a corner at 10 % of the Nyquist
frequency for tap tap (i.e. 5 % of its sample rate);
•
filter = 2 creates a filter with a corner at 20 % of the Nyquist
frequency for tap tap (i.e. 15 % of its sample rate); and
•
filter = 5 creates a filter with a corner at 50 % of the Nyquist
frequency for tap tap (i.e. 25 % of its sample rate).
When LOWLATENCY is active, this command is used to set the tap used
as the source of low-latency data. Data from this tap is decimated
inside the DSP and output on a separate stream at a rate 10 times
slower than the configured rate.
MICROG
Syntax: level MICROG
Sets the output level above which a trigger will be declared when
using the LEVEL triggering algorithm. level is measured in counts.
HIGHPASS
Syntax: filter HIGHPASS
Instructs the DM24 to pass the stream(s) which generate LEVEL triggers
through a high-pass filter before examining them. filter can be:
•
1, for a 100 s high pass filter;
•
2, for a 300 s filter;
•
3, for a 1000 s filter; or
•
0, to disable the high pass filter.
PRE-TRIG
Syntax: time PRE-TRIG
October 2009 69