Continuous and Single Sequence Acquisition


Continuous and Single Sequence Acquisition:



Oscilloscopes typically provide multiple approaches to acquiring and displaying data. The two most common and most distinct approaches are continuous acquisition and single-sequence acquisition.

Continuous Acquisition

In continuous acquisition mode, the waveform is generally displayed in real-time as the data points are acquired. Depending upon the time base being used, the scope may use either of the approaches below to display the data:

  1. If the time base is long enough, the wave form plot starts at the left sid of the plot window and propagates to the right across the screen. Once the right side of the plot is reached, one of two things happen (depending upon the particular oscilloscope being used, or the options selected on the oscilloscope controls):
    • The wave form “wraps around” and re-appears at the left side of the plot window and then resumes its left-to-right motion across the plot window
    • The wave form shifts left across the plot window so that new data points always appear at the right side of the plot window—giving the appearance that the plot window is scrolling across the wave form.
  2. If the time base is short, the oscilloscope displays successive “frames” of data, like the frames of a movie.

Single-Sequence Acquisition

In single-sequence acquisition, the data are not displayed to the plot window as they are acquired. Instead, the data are saved in memory (buffered). Once an entire plot window worth of data points have been saved, they are simultaneously displayed to the plot window. This approach is similar to the second approach in continuous acquisition except that once the wave form has been displayed to the plot window, data acquisition stops. Also, the way in which data are displayed is not dependent upon the time base. The overall effect is that a single “snapshot” of the waveform is displayed to the screen. This data acquisition approach is especially useful if a limited amount of data is desired near some “event”.

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