Guralp Systems CMG-DM24 User Manual
Page 32
CMG-DM24
expects to receive two-byte packets from the central timing source,
which may have its own GPS unit, or take signals from one of the radio
time standards. Choose the mode you require from the drop-down
menu.
Enable GPS power cycling : If you are using a GPS unit to receive time
signals, but do not experience significant drift in the system's clock
(for example, in a stable-temperature environment), you can save
power by selecting Enable GPS power cycling. With this option in use,
the GPS time is only checked at intervals of a specified number of
hours. Disabling this option keeps the GPS unit running constantly; if
you have ample power, this will give the most accurate results. You
can choose any whole number of hours for the interval.
Output control
The Output control tab allows you to configure which data streams are
sent to Scream! from the digitizer.
Güralp digitizers initially sample incoming data at a high rate (e.g.
2000 Hz for the DM24), which is then filtered and reduced to a lower
rate (decimated) using an on-board digital signal processing unit, or
DSP. The DSP has several filtering/decimation stages, which run one
after the other. Stages which can produce output are called taps. The
Güralp DM24 can output 4 taps simultaneously.
32
Issue N