This mode doesn't allow the analyzer to automatically synchronize
if the BER becomes greater than the sync threshold. For example,
the analyzer will not re-synchronize after momentary clock loss.
N O T E
Adjusting the data input delay may cause momentary clock loss. If you select
Manual Sync mode, this may also result in sync loss.
•
Burst sync mode is a special operating mode for measuring data in
bursts of bits, rather than one continuous stream of bits.
For more information, refer to
“Introduction to Burst Sync Mode” on
.
N O T E
If the error detector is in Manual Sync mode, it is recommended that you keep an
eye on the SYNC LOSS light at the top of the instrument. There are various actions
that can lead to loss of synchronization. Check the SYNC LOSS any time you make
changes to the instrument.
What is False Synchronization?
For patterns other than PRBS, the error detector may gain sync at a
point in the pattern that meets the sync threshold, but is not the correct
point where the internal reference pattern and the received data
pattern match. This is called false synchronization.
N O T E
False synchronization cannot occur with PRBS patterns because a 1 bit
misalignment would cause a measurement of 50% or more errors. Thus, the BER
during a misalignment would always be greater than the sync threshold BER.
For example, consider a pattern of 1000 ones and 1000 zeros as shown
in the following figure. With reference alignment 1 the patterns are
totally out of phase and the error detector is measuring 100% errors.
But as the reference moves closer to optimum alignment, the percentage
of errors gradually approaches zero (reference alignment 2 and 3). For
exact alignment, the sync threshold must be set lower than the BER
caused by a 1 bit misalignment, in this case 1E-3.
4
Setting up the Error Detector
142
Agilent J-BERT N4903 High-Performance Serial BERT
Summary of Contents for J-BERT N4903
Page 1: ...S Agilent J BERT N4903 High Performance Serial BERT User Guide s Agilent Technologies...
Page 68: ...2 Setting up Patterns 68 Agilent J BERT N4903 High Performance Serial BERT...
Page 158: ...4 Setting up the Error Detector 158 Agilent J BERT N4903 High Performance Serial BERT...
Page 314: ...6 Evaluating Results 314 Agilent J BERT N4903 High Performance Serial BERT...
Page 374: ...7 Jitter Tolerance Tests 374 Agilent J BERT N4903 High Performance Serial BERT...
Page 394: ...8 Solving Problems 394 Agilent J BERT N4903 High Performance Serial BERT...
Page 434: ...Index 434 Agilent J BERT N4903 High Performance Serial BERT...
