LeCroy DDA 7 Zi series, Operator'S Manual

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WavePro 7Zi
405
WP700Zi-OM-E-RevA
MJSQRj MJSQ Random Jitter is determined by finding the average of the two standard
deviations of the best-fit Gaussian distributions to the left and right sides of the measured jitter
probability density function.
MJSQDj MJSQ Deterministic Jitter is the difference between the mean values of the best-fit
Gaussian distributions to the left and right sides of the measured jitter probability density function.
Bathtub Curve
The bathtub curve is the integral of the jitter probability density function (PDF -- derived by normalizing the
extrapolated TIE histogram -- see the Theory section) for all possible sampling points within one unit interval (UI).
The right side of the bathtub curve is the integral of the jitter pdf from approximately -1/2 of a UI to zero and the
left side is the integral from +1/2 of a UI to zero, where the jitter PDF is centered about zero, and zero is defined
as the ideal crossing time of a bit. The bathtub curve is normalized to 1 UI. It is a logarithmic representation of bit
error rate (BER) vs. the sampling point. The greater the degree of separation between the sides of the bathtub
curve, the better the BER.
The horizontal distance between the sides of the bathtub curve at a given Y value (bit error rate) is a measure of
the eye width at that bit error rate.