492 Keysight M8000 Series of BER Test Solutions User Guide
8 Working with Measurements
• Total Jitter RMS: The average of the left and right jitter histogram root
mean squared values.
• Jitter Mean: Mean value for total jitter. Calculated as the weighted
average of the left edge jitter histogram.
• Random Jitter RMS: The total jitter component with Gaussian
distribution. After transforming a contiguous range of measured points
into Q space and performing a linear regression, it is calculated as the
mean of the sigmas of the two straight lines. The contiguous range is
limited by the BER Threshold and the Min. BER for RJ/DJ Separation
threshold.
• Deterministic Jitter: The total jitter component with non-Gaussian
distribution. After transforming a contiguous range of measured points
into Q space and performing a linear regression, it is calculated as the
period minus the difference between the means of the two straight
lines.
• Estimated Total Jitter: A forecast of the expected jitter for very low bit
error rates. After extrapolating the measured BER curves, it is
calculated as the period minus the expected width of the eye opening.
• Left Edge No. Points: The the number of points that has been
measured between the BER Threshold and the Min. BER for RJ/DJ
Separation threshold. It is displayed for both slopes. This number has to
be greater than 2 for the RJ, DJ, and estimated TJ values to be
applicable.
• Left Edge R^2: The R^2 values are calculated for both slopes of the
bathtub curve. They are a measure of how well the transformed points
between BER Threshold and Min. BER for RJ/DJ Separation fit to the
linear regression. They have to be greater than 0.75 for the RJ, DJ, and
estimated TJ values to be applicable.
• Right Edge No. Points: The number of points that has been measured
between the BER Threshold and the Min. BER for RJ/DJ Separation
threshold. It is displayed for both slopes. This number has to be greater
than 2 for the RJ, DJ, and estimated TJ values to be applicable.
• Right Edge R^2: The R^2 values are calculated for both slopes of the
bathtub curve. They are a measure of how well the transformed points
between BER Threshold and Min. BER for RJ/DJ Separation fit to the
linear regression. They have to be greater than 0.75 for the RJ, DJ, and
estimated TJ values to be applicable.
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