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Reference
3-2 GB1400 User Manual
Recalling the Default Setup
The default setup of the Generator and Analyzer are shown in the Appendix. To
return the Generator or Analyzer to this setup, use the following procedure:
1. Turn instrument power off.
2. While holding down the VIEW ANGLE, MSB 1, and (PATTERN) CLEAR
keys simultaneously, turn instrument power back on.
3. After you see the message Default Settings appear in the display, release the
three keys. In a few seconds the normal display format will appear and the
instrument will be in its default setup.
Locking the Front Panel
The instrument's front panel may be "locked" or "unlocked" using the PANEL
LOCK control. When the front panel is locked, all keys that can cause a setup
change are disabled. It is often useful to lock the front panel during a long or
critical test to prevent accidental loss of test results. Note that the LED in the
PANEL LOCK control indicates whether the front panel is locked (LED on) or
unlocked (LED off).
Simply press the PANEL LOCK control to toggle between the locked (LED on)
and unlocked (LED off) state.
Selecting a Pattern
The following section defines the patterns that can be generated and analyzed by
the GB1400 and how to set up the Generator and Analyzer to use a particular
pattern. Note that the Generator and Analyzer are compatible with the same suite
of test patterns and use the same setup procedures.
Pattern Definitions
The GB1400 can generate and analyze Pseudo-random bit sequence (PRBS) and
WORD test patterns. Each type has its own set of advantages and uses.
PRBS Patterns
Pseudo-random bit sequence (PRBS) patterns are designed to simulate "live
traffic" and have been standardized by the telecommunications and computer
industries. As a result they are often used to characterize or qualify new devices
or systems. Two key characteristics of a PRBS are its overall length in bits and
maximum number of contiguous 0s. The length of a PRBS pattern has the form
2
n
-1. For example a 2
23
-1 PRBS contains 8,388,607 bits. The maximum number
of contiguous 0s in a PRBS pattern is n-1, for example 22 in a 2
23
-1 PRBS.