Tj Total jitter at a specific BER. The value is determined by the width of the curve
expressing the confidence limits of the extrapolated TIE histogram. The value
represents the expected range of values observed for a number of observed
measurements equal to 1/BER. The Tj parameter is accumulated over all
acquisitions since the start of the measurement, or the last clear sweeps
operation. The total population of the TIE histogram is indicated in the waveform
descriptor box for the bathtub curve and Htie (the TIE histogram)
Rj Random jitter is obtained indirectly by first determining deterministic jitter
through various direct analyses of the TIE trend. Once all of Dj is found, the Rj
value is deduced from the equation Rj = (Tj(BER) - Dj)/ Tj
(1-sigma)
(BER), where the
value for BER is typically 10e-12 (i.e., Rj is not a function, but a single value). The
bit error rate is selected in the @BER (pow 10) control in the jitter menu. Rj is
expressed in terms of an RMS value, whereas Tj and Dj are expressed as peak-to-
peak values.
Dj Deterministic jitter is the peak-to-peak non-random part of the total jitter. This
parameter is the sum of the measured peak-to-peak values of periodic jitter (Pj)
and data dependent jitter (DDj). The DDj includes the effects of both inter-symbol
interference and duty cycle distortion.
Pj Pj is the peak-to-peak magnitude of the periodic components of the TIE trend. It
is measured by analyzing peaks in the Fourier transform of the trend of the time
interval error. It is necessary to specify the pattern repetition length (if there is one)
so that spectral lines harmonically related to this pattern rate do not contribute to
the estimate of Pj, since the spectral energy associated with data pattern-related
spectral components is included in the DDj measurement. The total periodic jitter
is the complex sum of the spectral components listed in the table under the Pj
breakdown tab.
DDj The peak-to-peak jitter caused by systematic effects related to the sequence
of data transitions.
344 SDA-OM-E Rev H
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