Technical data

Restrictions for Error Location Capture
Error Location Capture is subject to the following restrictions:
• Only memory-based patterns with a unique 48-bit pattern (detect word) are
allowed.
• The error detector must be aligned to the incoming stream.
• No alignment features can run during error location capture: Auto Align, 0/1
Threshold Center, Data Center
• No other advanced measurement (Output Timing, Output Levels, etc.) can be
running.
• Error Location Capture can only run when the BER Location Mode is set to
more than one bit (for example, all bits, or a block with a length > 1).
How to Run Error Location Capture
The following steps are recommended for running Error Location Capture:
1
Reset the instrument.
2
Load a pattern from the pattern folder to the Pattern Generator and to the Error
Detector.
3
Synchronize the Error Detector.
4
Clear the status registers.
5
Set up the Operation Status register so that it triggers when Error Location
Capture starts.
The Operation Status register should catch positive transitions on the ERR LOC
CAPTURE bit (bit 14).
6
Start the Error Location Capture. This is an overlapped command.
7
Set up a loop that queries the Operation Status register until the Error Location
bit goes high. This indicates that the Error Location Capture has started.
N O T E
Because Error Location Capture would run forever if no errors are detected, it is
recommended to also set up a time-out in your program.
How to See if Error Location Capture has Stopped
To see if Error Location Capture has stopped:
1
Set up the Operation Status register so that it triggers when Error Location
Capture stops.
Recommended Programming Techniques 3
Agilent J-BERT N4903B High-Performance Serial BERT 43