a certain number of loops it is diverted into the error detector. This way,
only a short burst of valid data reaches the Serial BERT followed by a
long break. Therefore, the error detector needs to be synchronized at
the beginning of every burst.
How Burst Sync Mode Works
The following figure presents the basic order of events that make up a
burst mode measurement. It also illustrates how the instrument
operates while in burst mode.
Gate In?
no
CDR?
yes
yes
Sync?
CDR Settling Time
Synchronization Time
no
BER
OK?
success
failed
Total Burst + 1
Bad Burst +1
Incr. Bit Counters
yes
no
Register Incoming Bits
Gate In?
no
yes
1
2
3
4
5
6
7
N O T E
Burst mode requires a complete measurement setup, including an external input
for the Gate In port. This input is used for the sync alignment.
1
Burst sync is started when the Gate In signal goes low, indicating
that a burst is arriving at the Data In port.
2
If the error detector is in CDR mode, it first tries to generate a clock
from the data. A short time interval is required to stabilize the clock
(the CDR settling time).
Setting up the Error Detector
4
Agilent J-BERT N4903 High-Performance Serial BERT
145
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...
