User`s guide

Data Channel - Select channel for data input.
Data Path - The Data Path button allows you to change directories if you frequently save measurement data to
directories other than C:\Visi.
Data Dependent Jitter (DDJ) - The jitter that is added when the transmission pattern is changed from a clock-like to
non-clock-like pattern. Includes Intersymbol Interference (ISI).
DDJ is generally due to bandwidth effects of the transmission media. The top view in the figure below shows a
traditional oscilloscope view of DDJ effects. Note: Low transition density areas reach a different voltage than
high transition density areas; this affects the Edge timing.
The bottom plot is from the dataCOM with Marker tool and shows a representation of the pattern where each edge
is actually a histogram of edge measurements. The jagged line represents the mean deviation of each edge relative
to its ideal time.
Data Standards - This selection determines the data rate of the signal and the 'Nominal Freq'. The selections are SATA1
(1.5gb/s Serial ATA), SATA2 (3.0 Gb/s Serial ATA gen2), PCI Express (2.5Gb/s) and custom. When custom is
selected, the data rate is entered in the 'Nominal Freq. (MHz)' entry box.
DCD + ISI HPF - This option applies to a High Pass Filter to the DCD+ISI data. The resulting, filtered data is plotted
on top of the raw DCD+ISI data in the DCD+ISI vs. Edge plot window. This feature allows the modeling of
receiver performance given the measured (transmitted) data pattern if the characteristics of the receiver are known.
Glossary © WAVECREST Corporation 2005
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