Guralp Systems CMG-DM24 - Manual (Page 13)

Operator's guide
3.2 Streams
The DM24 organizes the data it produces into streams. Each stream
has a 6-character identifier. The first four characters are taken from the
System ID of the digitizer. When you receive the instrument, the
System ID is set to its serial number, but you can change it in Scream!
or with a terminal command.
The next character denotes the component or output type:
•
Z, N, and E denote the vertical, north/south, and east/west
components respectively.
•
X denotes the fourth full-rate data channel, which is provided
for connection to your own monitoring equipment via the
AUXILIARY connector (if present).
•
C denotes the calibration input channel, which replaces the X
streams whilst calibration is in progress.
•
M denotes one of the 16 slow-rate Mux (multiplex) channels.
Three of these (M8, M9 and MA) are used to report the sensor
mass positions. Channels MC and MD are connected to the X and
Y axes of the downhole inclinometer.
•
For Z, N, E, X, and C streams, the last character represents the
output tap. Taps correspond to stages in the decimation process
within the digitizer, allowing the DM24 to output several
different data rates simultaneously. There are four taps,
numbered 0 to 3; 0 has the highest data rate and 3 the lowest.
Data streams end in 0, 2, 4 and 6 for taps 0, 1, 2 and 3
respectively.
If you configure the DM24 to output triggered data, this will
appear in separate streams ending with the letters G, I, K or M
for taps 0, 1, 2 and 3 respectively.
The DM24 also generates a stream ending 00. This is a status stream
containing useful diagnostic information, in plain text form (see
Section 6.1, page 89).
Digitizers for multiple instruments
The standard DM24 has 4 full-rate channels: one per component of a
triaxial instrument, plus the auxiliary and calibration channel.
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