Keysight M8190A - Theory of Operation

5 Streaming
154 M8190A User’s Guide
5.3.2 Theory of Operation
The following drawing shows a sequence used as ring buffer.
Sequence Table Entry 0
Sequence Table Entry N
Sequence Table Entry 4
Sequence Table Entry 3
Sequence Table Entry 2
Sequence Table Entry 1
Sequence
Restart
Initiate Sequence
Restart
Execute Sequence
Restart
Update Sample Data
Executed Segment
Figure 5-3: Sequence used as Ring Buffer
The sequence starts at sequence table entry 0 and consists of more than
5 sequence table entries. The automated restart is initiated when starting to play the
second segment. The restart itself is done at the end of the sequence. In this example,
the sample memory of the segment related to sequence table 2 is written, while
sequence table entry 4 is executed.
Streaming requires reloading the sample memory while executing to other parts of the
memory. It must be guaranteed that only those parts are overwritten, which have
already been played.
In order to handle this issue, the following two things are required:
1. The controlling software must know exactly the segment that is currently in use.
The state of the sequencer, including the currently executed segment can be read
using an API call (refer to the sections 8.7.7 and 8.21.9).
2. A minimum distance of 512 sequence vectors between the sample data of the
currently executed segment and the currently modified sample data is required.