Pattern Alternation - Agilent Technologies N4906B Serial BERT User Manual

Setting up the Pattern Generator
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Pattern Alternation

This section explains the basic purpose of alternating patterns. Two
alternate patterns can be stored in one pattern file.
Standard and Alternating Patterns
With the Serial BERT, you have full control on the data stream that is
sent by the pattern generator to your device under test. You can use
standard patterns to specify a test data pattern that is sent to your
DUT repeatedly.
Or, you can use alternating patterns to specify two patterns that are
sent to the DUT alternately. To implement alternating patterns, the
instrument's user pattern memory is split into two portions; one for
pattern A and one for pattern B.
The differences between these patterns are:
• Standard patterns consist of one single pattern that is repeatedly
sent. Any arbitrary pattern up to 32 Mbit length can be set up.
However, there are no further configuration possibilities. This
pattern is sent as long as the output port is enabled.
See "Setting up Patterns" on page 19 for more details.
• Alternating patterns consist of two patterns, one of which is
pattern A (the A half), the other is pattern B (the B half). Both
patterns are of equal length, each up to 16 Mbit.
The Alternate Pattern Control dialog box lets you control when which
pattern is sent. See the online Help for details.
When to Use Alternating Patterns
Alternating patterns can be used:
• To systematically insert errors in the bit stream at particular
positions.
The error detector expects pattern A only. If you set up pattern B so
that there are only minor differences, when you run the test, the
error detector will detect the changed bits as errors.
• To see how long it takes your DUT to settle.
You can set up an easy-to-process output stream as the standard
pattern, and a difficult output stream as the alternate pattern (for
example, all 0s for the standard pattern, and alternating 1s and 0s
Agilent N4906B Serial BERT, User's Guide, October 2005
Pattern Alternation