Agilent Technologies J-BERT N4903B, User Manual, Page: 61 / 572

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Setting up Patterns
Setting up Patterns - Concepts
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.
N O T E
In "8B/10B Symbol Comparison" and "Bit Comparison without PCIe3 SKPOS"
modes, only twelve different user patterns (UPAT1 ... UPAT12) and user pattern files
are allowed as analyser pattern.
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.
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.
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.
Agilent J-BERT N4903B High-Performance Serial BERT
User Guide
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Hardware-Generated Patterns
Memory-Based Patterns