Guralp Systems CMG-DM24 - Manual (Page 65)

Operator’s Guide DM-24 Digitiser
Issue G January 2003 63
The possible filter configurations are shown in the following table:
Tap# Samples/sec Bandwidth 1
Hz
Bandwidth 2
Hz
Bandwidth 5
Hz
0 200 10 - 90 20 - 90 50 - 90
1 100 5 - 45 10 - 45 25 - 45
50 2.5- 22.5 5- 22.5 12.5- 22.5
40 2 - 18 4 - 18 10 - 18
25 1.25- 11.25 2.5- 11.25 6.25- 11.25
20 1- 9 2- 9 5- 9
2 50 2.5 - 22.5 5 - 22.5 12.5 - 22.5
25 1.25- 11.25 2.5- 11.25 6.25- 11.25
20 1 - 9 2 - 9 5 - 9
10 0.5- 4.5 1- 4.5 2.5- 4.5
8 0.4- 3.6 0.8- 3.6 2- 3.6
5 0.25- 2.25 0.5- 2.25 1.25- 2.25
4 0.2- 1.8 0.4- 1.8 1- 1.8
2 0.1- 0.9 0.2- 0.9 0.5- 0.9
3 25 1.25- 11.25 2.5- 11.25 6.25- 11.25
10 0.5- 4.5 1- 4.5 2.5- 4.5
5 0.25- 2.25 0.5- 2.25 1.25- 2.25
4 0.2- 1.8 0.4- 1.8 1- 1.8
2 0.1- 0.9 0.2- 0.9 0.5- 0.9
1 0.05- 0.45 0.1- 0.45 0.25- 0.45
As can be seen from the list the choice of required filter will tend to define the set of
permissible sample rates required. The filter combination is set using the bandpass
command, which takes the tap number (0-2) and bandwidth factor (1, 2 or 5) as
arguments. For example:
2 5 bandpass
defines the narrowest filter on the output from tap #2, the 20 samples/sec tap in our
example, corresponding to a filter with corners at 5.0Hz (50% Nyquist) and 9.0Hz (90%
Nyquist). The system response to the above command would be:
Tap#2 20 s/s Bandpass: 5.0->9.0Hz