Guralp Systems CMG-6TD User Manual
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Configuration with Scream!
During boot-up, each unit reports its model type, firmware revision number,
its System ID and serial number. This information is followed by the number
of resets that have occurred and the time of the latest reboot from its internal
clock. The following lines report the current configuration of the unit's
sample rates, output taps, and baud rates. A typical digitiser re-boot status
message looks like this:
The system will produce a similar status message whenever it is powered up,
and whenever you reboot it (normally, after changing its configuration).
5.3.1 GPS
If a GPS unit is fitted, its operational status is reported on reboot and the
behaviour of the time synchronisation software will also be shown.
From a cold start, GPS will initially report No GPS time together with its last
position (taken from the internal backup). All messages from the GPS that
involve a change of its status are automatically reported. Repeated status
messages are not shown to avoid unnecessary clutter.
The report shows the satellites that the system has found, and their
corresponding signal strengths.
If the system has not been moved from its previous location, it should be able
to find enough satellites to obtain an accurate GPS time fairly quickly; if the
GPS receiver has difficulty finding satellites, there may be a delay of several
minutes before a new message is displayed.
Before beginning, the digitiser's internal time synchronisation software will
wait for the GPS unit to report a good position fix from at least three satellites,
for at least six consecutive messages. Messages are normally received every
ten to twenty seconds.
The system will then set the internal clock and re-synchronise the
analogue-to-digital converters so that the data are accurately time-stamped to
the new reference. Any data transmitted up to this point will be stamped
with the time from the internal backup clock, which is set to the new accurate
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Issue F - February 2014