User guide

The Spectral Jitter measurement detects even small periodic components that may
be hidden in a high level of random noise. It informs you about the frequencies of
such components and measures their contribution to the total jitter.
This helps to identify jitter sources and to reduce or eliminate their influence.
Prerequisites for Using the Spectral Jitter Measurement
It is important that the initial sampling point is in optimum position (i.e. in the
middle of the eye opening), because the Spectral Jitter measurement derives its
starting sampling point from that point.
See also “General Requirements” on page 228.
How the Spectral Jitter Measurement Works
The Spectral Jitter measurement performs a capture and compare operation in the
jitter region. The number of compared and captured bits is adjustable.
By default, the analyzer sampling point is set to an offset of -0.5 analyzer clock
periods or unit intervals (UI) from the optimum sampling delay.
Capture and compare means that a certain amount of incoming data is captured
and also compared with expected data in real time. The number of captured data
points is adjustable.
While the measurement is running, correct and incorrect data is captured. The
resulting records contain the captured data and the corresponding error
information.
Advanced Analysis 6
Agilent J-BERT N4903B High-Performance Serial BERT 343