Guralp Systems CMG-DM24 - Manual (Page 11)

Operator's guide
3 Using the DM24
Once the DM24 is connected to your equipment, it will start producing
data immediately. You can now start configuring it for your own
needs. There are two ways you can do this:
•
using the graphical interface provided by Scream!, or
•
over a terminal connection (see Chapter 5, page 51).
Both methods provide full access to the configuration options of the
digitizer.
In most circumstances, you will use Scream! to operate the system. For
complete information on how to use Scream! to configure and control
your instrument, please refer to the Scream! user guide.
3.1 Taps
The DM24 converts analogue signals to digital data at a high sample
rate, which is then reduced in steps. This process is known as
decimation, and each output stage is called a tap.
The highest data rate you can choose is 1000 samples/s. This rate can
only be produced by Tap 0, the first tap. Tap 0 can also produce data
at 500, 400, 200 or 100 samples/s.
After Tap 0 there are three more taps. Each tap produces data at an
integer sample rate, which must be 2, 4, 5, 8 or 10 times lower than the
previous tap.
For example, the following is a possible sequence:
Tap 0 : 500 samples/s
Tap 1 : 50 samples/s (divide by 10)
Tap 2 : 10 samples/s (divide by 5)
Tap 3 : 5 samples/s (divide by 2)
The digitizer always generates all four sample rates, but it does not
have to output them. You can configure any set of taps to output. You
can also have different taps configured for different sensor
components.
October 2009 11