Guralp Systems CMG-CD24 - Manual (Page 59)

Operator's Guide
5.4 Output configuration
5.4.1 SAMPLES/SEC
Syntax: tap-0 tap-1 tap-2 tap-3 samples/sec
The DSP software on the CD24 supports up to 7 cascaded
filter/decimation stages. Each stage can be set to one of three
decimation factors, which divide the sample rate by 2, 4 or 5.
Decimation factors of 8 and 10 are also available, which the CD24
produces by combining two decimation stages. As a result, data can be
output at up to 4 concurrent data rates. These configured output
stages are called taps.
The ADC within the unit outputs data at 2000 samples/s, so taps can
have sample rates between 1 and 1,000 samples/s.
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 or 10. Non-integer
values are not allowed.
For example:
1000 250 125 25 samples/sec
500 100 5 1 samples/sec
200 100 20 4 samples/sec
400 40 20 10 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
5.4.2 SET-TAPS
Syntax: tap-0 tap-1 tap-2 tap-3 SET-TAPS
Sets which components are output under normal conditions, and at
which tap(s).
tap-0 to tap-3 are integers below 8, whose binary bits represent the
Z (1), N (2) and E (4) components respectively. Each one sets which
components are output at that tap under normal conditions. You
cannot set tap 0 to output streams.
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