Guralp Systems CMG-3ESPCD - Manual (Page 63)

CMG-3ESPCD Digital Broadband Seismometer Command line interface
The AZIMUTH command only alters the digitiser's CMOS settings. You will
need to re-boot the digitiser to transfer them to the DSP.
6.2.6 CROSS
Syntax: channel CROSS
Alters the DSP's transformation matrix to invert one of the digitiser channels.
The argument channel is one of 0 (vertical), 1 (N/S), 2 (E/W) and 3
(auxiliary).
The CROSS command only alters the digitiser's CMOS settings. You will
need to re-boot the digitiser to transfer them to the DSP. If you need to set
both AZIMUTH and CROSS, you must issue AZIMUTH first, since it overwrites
the matrix.
6.3 Output configuration
The commands in this section control the serial data output.
6.3.1 SAMPLES/SEC
Syntax: tap­0 tap­1 tap­2 tap­3 samples/sec
The DSP software on the digitiser supports up to 7 cascaded filter/decimation
stages. At each stage, the sample rate can be decimated by a factor of 2, 4 or 5.
The fixed decimation stages output data at 2,000 samples/sec, 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 digitiser will
arrange the remaining stages according to your settings.
The arguments tap­0 to tap­3 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. The following four examples are
all valid settings:
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:
MAN-C3E-0002 63 Issue B - November 2013