SDA Operator’s Manual
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 level field and enter a percentage value, using the pop-up
keypad. The level is automatically set to the selected percentage on each acquisition.
Note: The absolute level setting should be used for jitter measurements over several acquisitions because the relative
setting can potentially remove jitter by tracking slowly, thereby varying level shifts that could occur between acquisitions.
5. Touch inside the Signal Type field and select a standard signal type from the pop-up menu.
The signal type defines the compliance masks and bit rates for the selected standard. If you
selected Custom from the Signal Type menu, touch inside the Bit Rate field and enter a bit
rate, using the pop-up keypad. By touching the Find Bit Rate button, you can have the bit
rate determined automatically. This button is also available when a standard data type is
selected.
SDA-OM-E Rev H 313
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