User guide

This function is useful for providing a "starting point" for sampling somewhere
within the data eye on the vertical voltage axis. It is recommended to use this prior
to clock/data alignments.
When used with the following patterns, this function may provide a 0/1 threshold
that requires no further adjustment:
• 2^n-1 PRBS patterns
• Patterns with 50% mark densities (large amplitudes and no excessive noise)
Bit Recovery Mode
Click this button to put the error detector in bit recovery mode (BRM). For details
on BRM see “Understanding Bit Recovery Mode” on page 195.
Then, click Auto Align to set the sampling point.
Sampling Point Display
This area of the Sampling Point Setup window graphically illustrates the
parameters of the current sampling point and data eye. Click anywhere in the
sampling point display to set the sampling point to that location.
A green area in the display indicates the voltage range specified in the Input
Range fields for non-differential modes (Normal and Complement). The Serial
BERT is searching this range to find the eye when calculating the optimum
sampling point.
Return to Results
Click this button to return the 0/1 Threshold and Data Delay to the values
measured during the last auto alignment. The Data Inverted and Avg. 0/1
Threshold checkboxes will be returned to their previous state.
5 Setting up the Error Detector
202 Agilent J-BERT N4903B High-Performance Serial BERT