Guralp Systems CMG-CD24 - Manual (Page 84)

CMG-CD24
7 Appendices
7.1 Appendix A - InfoBlocks
The CD24 has a 1kb buffer inside its firmware memory which can be
used to store information about attached sensors. Users are free to
store any data they wish in the digitiser's InfoBlock (information
block).
Typically, this is used to store calibration parameters, poles and
zeroes, etc. Newer digital sensors have their calibration information
pre-loaded into the information block, in the format described below.
Software applications, such as Scream!, can read the information and
use it to display values using physical units rather than counts.
Information about viewing and uploading digitiser information blocks
using Scream!'s graphical user interface can be found on our website at
www.guralp.com/articles/20071012-howto-upload-infoblock but, if
Scream! is not available, InfoBlocks can be loaded from the digitiser
command line using the LOAD-I command, as described in section
5.2.4 on page 55.
7.1.1 Format of the default information block
The calibration information begins with the line [instrument­id].
The instrument­id is formed from the system ID and stream ID
(serial number), separated by a dash, e.g. GURALP­DEMO. It is also the
string which identifies the digitiser in the lefthand pane of Scream!.
This information is not actually used by the digitiser or by Scream!,
but is included for consistency with the calvals file and other utilities
(see www.guralp.com/articles/20060818-howto-scream-scaling and the
Scream! manual for information about the calvals file).
After the identifier, calibration information is stored in the form
FIELD=VALUE, with one field on each line. The fields used are shown
below:
Field Value
Serial­Nos
[optional]
An optional serial number to be displayed in the
title of Scream! graphs.
VPC The sensitivity of the Z, N/S, and E/W digitiser
input channels, in V per count, separated by
μ
commas. These are given on the digitiser
calibration sheet.
G The gain of the Z, N/S, and E/W sensor
84 Issue C