Teledyne LeCroy JTA2 - Manual (Page 5)

JTA2-OM-E Rev A ISSUED: December 2003
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ACCESSING JTA2
To access JTA2's special features, you must first purchase and install the option. Once installed,
JTA2's math and parameter selections will appear in the Math and Measure menus.
TIMING FUNCTIONS
JitterTrack, PersistenceHistogram and PersistenceTrace are timing functions in LeCroy’s JitterPro
and JTA jitter and timing analysis packages. The JitterTrack feature is key to identifying the
source of excessive jitter or non-normal jitter characteristics. A timeline of signal jitter that is
synchronous with the signal under test allows you to view patterns that would remain invisible
using other systems, zoom to areas containing maximum jitter, and troubleshoot the problem.
PersistenceHistogram is the ideal quantitative "companion" to persistence display. It histograms a
horizontal or vertical slice of the persistence waveform. Utilizing average, sigma, and range
settings, PersistenceTrace computes a vector trace from a bit map to give insight into edge
details down to a few picoseconds.
• JitterTrack graphically plots as a function of time the amplitude of the waveform
attributes Cycle-to-Cycle variation, Duty Cycle, Interval Error, Period, Width, and
Frequency. Interval Error, for example, calculates the timing error of a signal compared
with an ideal, expected interval defined by a user-specified reference frequency, the most
common estimator of jitter. "The short-term variations of a digital signal’s significant
instants, from their ideal positions in time," are plotted. This is the perfect tool for
characterizing clocks in synchronized telecom networks such as SONET and SDH. A
special data function, available for most of these attributes, enables work on random data
streams.
• Persistence Histogram analyzes a vertical or horizontal slice of a persistence map of
multiple waveforms. The resultant bar chart shows a numerical measurement of the
timing variations of a signal, which are observed qualitatively in the persistence display of
the signal. A typical application is characterizing the jitter in a communications signal eye
diagram.
• Persistence Trace is a method for displaying the data acquired from multiple sweeps of
a waveform. A vector trace is computed, based on the bit map of the underlying multiple
signal acquisitions. Detail is then represented in a choice of three graphic forms, each
representing a different characteristic of the waveform. Insight into edge details is given
down to a few picoseconds — valuable in applications such as the examination of fast
signal transitions.