Guralp Systems CMG-DM24 - Manual (Page 61)

Operator's guide
The USB interface is provided by an internal FTDI245 chip, which is
compatible with Microsoft Windows, Linux and Apple Macintosh
systems.
You can use the USB port only to connect to a computer, not directly
to a peripheral (e.g. a hard disk). If you want to download data to a
hard disk, you should specify the FireWire interface instead.
5.5 Output configuration
SAMPLES/SEC
Syntax: tap-0 tap-1 tap-2 tap-3 samples/sec
The DSP software on the DM24 supports up to 7 cascaded
filter/decimation stages. At each stage, the sample rate can be divided
by a factor of 2, 4 or 5. The internal ADC outputs data at 2000 samples
per second, so decimated data streams are available from 1,000, 500
and 400 samples/sec down to 1 sample/sec.
You can specify the sample rate to use at four of these stages, known
as taps. You can also take output from any of these four stages. The
DM24 will arrange the remaining stages according to your settings.
The arguments tap-0 to tap-3 are the sample rates at each tap in
turn, starting with the highest. You must ensure that each rate is lower
than the previous one by a factor of 2, 4, 5, 8 (= 2 then 4), 10 (= 2 then
5) or 16 (= 4 then 4). Non-integer values are not allowed.
For example:
1000 125 25 5 samples/sec
1000 500 100 10 samples/sec
500 100 20 4 samples/sec
400 40 10 5 samples/sec
As long as you specify the initial taps, you can omit later ones. The
command fills in the value of the missing taps, using a decimation
factor of 2 where possible. Thus, the following commands are
equivalent:
400 40 20 10 samples/sec
400 40 samples/sec
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