Acquiring Waveforms
CSA7000 Series, TDS7000 Series, & TDS6000 Series Instruments User Manual 3-31
Samples sets the minimum number of samples required to complete a single
acquisition sequence and the minimum number of samples required to
complete a mask test. If not using display persistence, samples sets the
minimum number of samples that is required to release the waveform to the
display. Similar to FastFrame, selecting RunStop, will cause the waveform
to be displayed with what has been acquired so far.
The actual number of samples acquired is determined by the Samples setting,
the selected Record Length, and if in equivalent time acquisitions, the actual
number of samples acquired in an acquisition. For example, in real-time
acquisition mode with the entire trace displayed, if the Record Length is set
to 5000 points and Samples is set to 5001 points, then two acquisitions are
required and 10000 points are acquired. If Samples is set to 5000 points, one
acquisition is required and 5000 points are acquired. If Samples is set to
4999 points, one acquisition is required and 5000 points are acquired.
For Single Sequence and Mask Pass/Fail Testing, a sample is only counted if
the sample would be displayed in the graticule area. In Single Sequence, all
eligible samples in an acquisition are counted. In Mask Test, with infinite
persistence on, all acquisitions acquired in a batch are counted. In nondisplay
persistence, the minimum number of samples for the waveform may include
multiple batches of acquisitions.
In ET mode, fewer samples are acquired per acquisition, but more acquisi-
tions may be acquired in a batch. Samples divided by the Record Length
roughly indicates the number of waveforms in a batch of acquisitions.
Batch processing minimizes the overhead of displaying and processing other
features, such as measurements and histograms. The higher the number of
samples, the greater the acquisition throughput and the potential for less
frequent display updates.
Also, consider how you want to control acquisition; you have two main options,
settable from the Run/Stop control window (select Run/Stop from the Horiz/Acq
menu):
HRun/Stop Button Only. Sets the instrument to start and stop the acquisition
only when you push the Run/Stop button, available on the front panel, or in
the Run/Stop control window. If toggled to Run, acquisition will start if a
valid trigger occurs. If toggled to Stop, acquisition stops immediately.