Guralp Systems CMG-DCM build <10,000 - Manual (Page 65)

Acquisition Modules and Platinum Firmware Data Handling
6 Data Handling
6.1 Introduction
The data handling system of the acquisition module is very flexible, due to its
modular software architecture. In the simplest configuration, all data flowing
through the acquisition module is routed through a single multiplexor module
called gdi­base. This communicates directly with all input modules, which
handle the various incoming data streams, and all output modules, which
convert the data into the required formats. All incoming data are stored and
accessed internally in an intermediate format, regardless of the format in
which it was originally received.
Note: The sole exception to this is incoming CD1.1 data which, for
reasons related to frame signing (an authentication technology), do
not pass through gdi­base. CD1.1 data-handling and the
associated system configuration are covered in a separate manual,
MAN-EAM-1100, which is available for download from
www.guralp.com .
The diagram below shows the basic internal organisation of an acquisition
system, ignoring the CD1.1 subsystem:
The multiplexor makes incoming data available to the output modules. These
come in two flavours: simple modules (such as those for WIN, GSMS and
QSCD) simply convert the data streams and output them in the required
format; other modules maintain a ring-buffer which is used to, for example,
satisfy BRP back-fill requests. The ring-buffers use the NAND flash memory.
These output modules also send data to gdi­record, which handles all mass
storage device writing requests, regardless of format.
MAN-EAM-0003 65 Issue E - February 2014