Agilent Technologies 71612, Quick Reference

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False Sync
False sync occurs when the equipment tries to achieve
synchronization, and although the error ratio falls below
the sync threshold value set, it is not properly
synchronized. This can happen with certain user-based
patterns but not with a PRBS.
For example:
Imagine a pattern with 999 zeros followed by a single one.
As the error detector tries to achieve synchronization, most
comparisons of incoming pattern to reference pattern yield
an error ratio of 2x10
-3
. Only one position gives error free
operation. However, the error ratio in the other positions
could easily be better than the synchronization threshold
set, and thus the error detector will say it has achieved
satisfactory operation.
Look for this when there is a stable error ratio which
cannot be explained in any other way. Change the sync
threshold value to a lower one - for example, from 10
-1
to
10
-7
. Synchronization will not be as fast with a more
stringent threshold but will be more accurate.
BER -
What is it?
71612-90017.fm Page 46 Wednesday, July 18, 2001 11:26 AM