User guide

How Can You Tell if Your Synchronization is False?
You may suspect false synchronization under the following conditions:
• You are using a pattern other than PRBS and the error detector gains sync, but
it measures a constant, fixed error ratio.
• You are using a pattern other than PRBS and the error detector gains sync, but
auto-search functions (Auto Align, Clock/Data Center, 0/1 Threshold Center)
repeatedly fail.
In a false sync, the sync threshold BER of 1E-3 may be met, but eye edges at
BER 1E-3 (required by an auto-search function) may not be found. This is
because BERs less than 1E-3 do not exist within the data eye.
If you suspect a false sync, try re-synchronizing at a sync threshold BER lower
than the fixed error ratio. If sync is acquired without the problems listed above,
then your previous sync was false. Your current sync should be on an exact
pattern alignment.
N O T E
While auto-search functions are in progress, the sync threshold BER is changed to
the same value as the alignment BER threshold. If you are using these functions
and want to consistently re-synchronize at a lower sync threshold, you must set the
alignment BER threshold to the same value as the sync threshold BER.
5 Setting up the Error Detector
210 Agilent J-BERT N4903B High-Performance Serial BERT