User guide

BERT connected to your device:
• There is no clock signal from your device.
• Your device is faulty.
DATA LOSS
This indicator turns red when no data signal is detected at the ED Data In port.
BERT connected looped back or to your device:
• The PG data output is off or not connected.
• There is no connection to the ED data input.
• The 0/1 threshold is not in the eye limits of the incoming data signal. Use Auto
Align or select Avg 0/1 Threshold.
• Your cables are faulty.
BERT connected to your device:
• There is no data signal from your device.
• Your device is faulty.
SYNC LOSS
This indicator turns red when the measured BER is higher than the sync threshold.
BERT connected looped back or to your device:
• The sampling point is incorrect. Use Auto Align.
• The data pattern is inverted. Toggle Data Inverted or use Auto Align.
• The ED pattern does not match the incoming data pattern. Make the ED track
the PG pattern, or set ED and PG patterns independently the same.
• Patterns have lost sync in manual sync mode. Use Auto Align, Sync Now, or
select Auto Sync mode.
BERT connected to your device:
• The data eye is very small. If Auto Align does not correct sync loss, set the 0/1
threshold manually.
• Your device has inverted the data pattern. Toggle Data Inverted or use Auto
Align.
• Your device has changed the data pattern. Set the ED and PG patterns
separately.
• If the fundamental BER of your device is higher than the sync threshold BER,
you can select a higher sync threshold BER.
Solving Problems 9
Agilent J-BERT N4903B High-Performance Serial BERT 471