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Reference
GB1400 User Manual 3-3
The PRBS patterns generated and analyzed by the GB1400 are listed below.
Table 3-1. PRBS (2
n
-1) Test Patterns
n Label Used in Generator
and Analyzer Displays
Length
(2
n
-1 bits)
Maximum Number of
Contiguous 0s
7 PN 7 127 6
15 PN 15 32767 14
17 PN 17 131,071 16
20 PN 20 1048575 19
23 PN 23 8388607 22
Word Patterns
Word patterns are programmable by the user. Word patterns can be designed to
cause specific stress characteristics, such as maximum jitter, or to simulate
framed patterns like SONET, SDH, or FDDI. The standard GB1400 Generator
and Analyzer will allow you to create and save up to ten 16-bit (two-byte)
WORD patterns in battery-backed memory. Or, with the 1-Mbit Option installed,
you can create and save up to ten 64 kbit WORD patterns (depends on buffer
settings) in battery backed memory. Note that the standard and 1-Mbit
instruments also store the current WORD pattern in battery-backed memory.
Selecting the Active Pattern
In this User's Guide, the pattern currently being generated by the Generator or
analyzed by the Analyzer is called the active pattern. Procedures to make a
selected PRBS or WORD the current active pattern are provided below.
Selecting PRBS Patterns
To select a PRBS pattern:
Press the PRBS key. The instrument will now be in the PRBS pattern mode.
Press the pattern up/down keys until the name of the desired PRBS pattern is
displayed. Available PRBS patterns are:
PN 7
PN 15
PN 17
PN 20
PN 23
The displayed PRBS pattern becomes the active pattern immediately.
Selecting the Current Word Pattern
To make the current WORD pattern the active pattern, simply press WORD key.