Setting Up Patterns - Agilent Technologies N4906B Serial BERT User Manual

Setting up Patterns

The purpose of data patterns is to simulate the type of data that your
device might receive in the real world. Different patterns present
different data loads to your device, which can cause variations in the
bit error ratio. A bit pattern is sent from the pattern generator to your
device. At the same time, the expected output pattern of your device is
internally generated in the error detector (to provide a reference).
Selecting a pattern is the first step in setting up a BER measurement.
The Serial BERT provides various patterns to fulfill most standard
testing needs.
How does the Serial BERT Generate Patterns?
The Serial BERT has two possibilities for generating patterns: either
by directly generating them from the hardware, or by loading patterns
into the memory and generating the output according to the pattern in
the memory. These memory-based patterns can be either user
patterns (file-based), or software-generated patterns.
Hardware-Generated Patterns
The hardware-generated patterns available with the Serial BERT are
PRBS 2^n –1 patterns. They provide long, high-speed, random traffic
patterns that can be used for testing a wide range of devices. These
patterns cannot be manipulated in any way.
Memory-Based Patterns
The memory-based approach is more flexible. It makes it possible to
define any pattern (within the physical limits of the memory) for
defining the output. The Serial BERT provides two possibilities for
defining the output: by defining user patterns or by selecting a
software-generated pattern.
User Patterns User patterns are file-based, editable patterns. These may be patterns
that you set up using the Serial BERT's Pattern Editor, or any of the
patterns delivered with the Serial BERT. You can easily define your
own patterns for any special requirements.
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Agilent N4906B Serial BERT, User's Guide, October 2005