This topic describes the Acquisition Setup dialog's Waveform tab when FlexDCA is in Scope Mode. Use the Acquisition Setup dialog's Waveform tab to define the way you want the instrument to acquire data from the input waveform.

Click Setup > Acquisition to open this dialog. Or, click the Acquisition button, located at the bottom of the screen.

By default, FlexDCA automatically:

• Sets the waveform record length to be based on Samples / Waveform,
• Selects the number of Samples / Waveform, and
• Turns Patten Lock off.

Pattern Lock. In Oscilloscope mode, a random PRBS signal can appear to be an MV waveform (like an eye diagram) even though the data is not stored in a database. Oscilloscope mode measurements cannot be made on these waveforms. To properly view such a signal in Oscilloscope mode, click the Pattern Lock button in this dialog or use a pattern trigger.

Random Single-Valued Waveform in Oscilloscope Mode

Pattern Lock On (measurements are valid)	Pattern Lock Off (measurements cannot be made)

With Acquire Entire Pattern on, each waveform acquisition captures data from the entire pattern. (Normally, only data from the displayed portion of the pattern is acquired.) The Minimum Timebase Position control establishes the start of the pattern and the Symbol Rate and Pattern Length determine the time duration. Long patterns may require some noticeable time to be acquired. When acquiring the entire pattern, the Pattern Navigation Display shown here is displayed at the top of the display.

You can select to specify waveform record length based on Samples / Waveform or Samples / UI. If you turn on Acquire Entire Pattern (requires that you first turn on Pattern Lock), the waveform record length will be based on Samples / UI and it cannot be changed to Samples / Waveform.

Automatic sets the optimum record length based on the width of the display graticule (2048 points). Therefore, in Automatic, a multiple of the graticule width is selected as the record length. This results in an even distribution of data points sampled from the input waveform. For example, Automatic may select 4096 points (two times 2048) as the record length. Manually setting the record length to a value other than a multiple of 2048 results in an uneven histogram of the waveform.