19-2233 PC2
2019-02-01
39(50)
ADQ7DC Manual
16-1796 PC2 2019-02-01
39(50)
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Use sample skip to reduce the data rate.
•
Use decimation to reduce data rate. Decimation is sample skip combined with digital filtering to
reduce noise and potential aliasing. This method requires the option –FW4DDC.
•
Use custom real-time implementation of the firmware in the FGPA. This requires the ADQ Develop-
ment Kit.
Use continuous streaming when there is a real-time infinite event going on, for example, a radio trans-
mission. Another application is when searching for a rarely occurring event and constantly analyzing
data in real time in the host PC for finding that event.
7.3.2
Triggered streaming acquisition
The triggered streaming is similar to the continuous streaming except that the data is cut into records.
Each record is recorded at a trigger event and has a limited distribution in time. Each record has a
header with timing information. The effective data rate to the PC is set by the trigger rate in combination
with the length of the record.
The acquisition memory has an important role for triggered streaming; handle bursts of triggers. Read-
out of a record can start as soon as the recording has started.
Use triggered streaming when a short re-arm time is critical. Or when the acquisition is driven by real-
time external events.
7.3.3
Multi-record acquisition
In the multi-record mode, a record is recorded into the acquisition memory and read out on request
from the user. The multi-record mode is straight forward to implement and is easy to use if the data set
is smaller than the on-board memory.
Readout only can start when the complete record is captured and is always initiated from the user's
application.
Figure 30: Continuous streaming timing.
Figure 31: Triggered streaming timing.
Figure 32: Multi-record timing.
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