Agilent Technologies N4906B Serial BERT User Manual page 29

User Patterns
CA UT ION
Agilent N4906B Serial BERT, User's Guide, October 2005
Implications of Using Memory-Based Patterns
There are several implications to the way Serial BERT handles
memory-based patterns, a few of which are:
• If you set up an alternating pattern where pattern B is a replica of
pattern A except for the addition of one error, and the pattern is an
odd number of bits long, the error will be repeated 512 times when
B is sent (because pattern B is sent 512 times before switching back
to A).
• If you want to send a periodic pattern, you only have to define a
single repetition. For example, if you want to send alternating 1's
and 0's, you only have to define the first two bits. This pattern is
automatically loaded 256 times to fill up a complete block of RAM.
• If you set up a trigger to be generated whenever a pattern is sent,
the trigger is sent whenever all blocks that store this pattern have
been sent (and not every time the pattern is sent).
So, for example, if you have a standard pattern that is 384 bits long,
this pattern must be loaded into the memory four times to reach the
512-bit boundary. A trigger would then be generated every
4 x 384 bits, or 1536 bits.
Example Patterns
The Serial BERT provides a set of example user patterns. These
patterns mimic real data packets and standard stress patterns.
The directory for the example user patterns is:
C:\N4906B\Patterns\Demo.
You can access this folder from the Serial BERT's Start menu
(N4906B Data -> Pattern).
Any changes you make to the patterns in this folder are non-
recoverable (there is no backup folder). To avoid inadvertent changes,
it is recommended that you copy the demo files to a different directory
before loading them.
Setting up Patterns
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