SDA Operator’s Manual
MJSQ Jitter
The other method of determining the random and deterministic components is based on the
procedure described in the Fibrechannel MJSQ (Methods for Jitter and Signal Quality) document.
This method is similar to the effective jitter described above except that it operates directly on the
jitter probability density function (pdf). A pair of normal distributions (one for each side) is found
by adjusting their standard deviations so that they best fit the tails of the measured pdf. The
difference between their mean values is the Dj and the average of their standard deviations is the
Rj. This method is shown as follows.
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.
SDA-OM-E Rev H 335
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