User guide

2
All measurement points that have BER between the BER Threshold and
Minimum BER for RJ/DJ Separation are transformed into Q-space.
The Q-factor describes the signal-to-noise ratio at the decision circuit. It is
described in “Understanding the Q-Factor Results” on page 282.
3
Linear regression is performed for both the left and right edges.
4
The mean and sigma are calculated for both lines:
– RJ is calculated as the mean of the two sigmas.
– DJ is calculated as the period minus the difference of the two means.
5
The estimated TJ is calculated:
– Linear regression is used to extrapolate the bathtub curve to lower BER
values.
– The intersections of the resulting lines with the Residual BER for RJ/DJ
Separation are located.
– The eye opening is calculated.
The estimated TJ is the period minus the width of the eye opening.
The illustration below shows a jitter curve where both RJ and DJ are present. It
also shows how the TJ peak-to-peak and RMS are calculated.
6 Advanced Analysis
244 Agilent J-BERT N4903B High-Performance Serial BERT