LeCroy DDA 7 Zi series, Operator'S Manual

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WavePro 7Zi
395
WP700Zi-OM-E-RevA
Each dialog has a default selection that represents the most common configuration. You can accept the defaults
by simply touching the Next button in each dialog.
SDA Basic Setup
Note: Many of the measurements in the SDA require both a high sampling rate and long memory to compute
accurately. Verify that you are in two channel mode (20 GS/s) and that at least 400k samples are being
captured before performing any SDA measurements. Lower sampling rates can result in less accurate jitter
measurements, and short record lengths can give incomplete eye patterns or jitter displays that diverge.
1. To access the SDA dialogs, press the Serial Data Analyzer (SDA) button on the Quick Access toolbar; or,
touch Analysis in the menu bar, then Serial Data in the drop-down menu. The display defaults to the
Scope dialog, which enables you to set up SDA measurements while you continue to view currently
displayed waveforms. Touching the
Scope button turns off SDA features.
In the image above are shown two measurement modes: Edge-Ref and Edge-Edge . The Edge-Edge
mode is explained separately in this manual; the information presented here applies mainly to the standard
(Edge-Reference) mode.
2. Touch inside the Data Source field and select a data source, then touch inside the Clock Source field and
select a clock input. If you want to recover the clock from the signal, touch the Recover clock checkbox;
the Clock Source field will become inactive. The "Crossing level(s)" section in this dialog allows you to set
the voltage level at which the signal timing is measured. The crossing level is set separately for the data
and clock (if an external clock is selected) and can be either absolute or relative. The
Absolute crossing
level in volts (or watts for an optical signal) can be set directly, or can be found automatically by touching
the
Find Data Level button. The level is found by locating the midpoint between the highest and lowest
signal levels in the current acquisition. The Relative level is automatically set to the selected percentage
on each acquisition.
3. There are two crossing-level controls in the SDA main dialog: one for the data signal under test and
another for the reference clock (if the
Recover clock checkbox is unchecked). The crossing time used by
both the jitter and eye pattern measurements is determined as the absolute time at which the signal level
crosses the selected threshold. Touch inside the
Data Level Is or Clock Level Is field and select either
Absolute or Percent from the pop-up menu.
4. If you selected Absolute, touch inside the Abs level field and enter a voltage value. Alternatively, you can
touch the Find Data Level or Find Clock Level button. If you selected Percent, touch inside the Percent