Acquiring and Displaying Waveforms
3–30 TDS 500C, TDS 600B, & TDS 700C User Manual
Figure 3–15 illustrates the different modes and lists the benefits of each. It will
help you select the appropriate mode for your application. Refer to it as your
read the following descriptions of each mode.
Sample Mode. In Sample mode, the oscilloscope creates a record point by saving
the first sample (of perhaps many) during each acquisition interval. (An
acquisition interval is the time covered by the waveform record divided by the
record length.) Sample mode is the default mode.
Envelope Mode. In Envelope mode, the oscilloscope acquires and displays a
waveform record that shows the extremes in variation over several acquisitions
(you specify the number of acquisitions). The oscilloscope saves the highest and
lowest values in two adjacent intervals similar to the Peak Detect mode. But
Envelope mode, unlike Peak Detect, gathers peaks over many trigger events.
After each trigger event, the oscilloscope acquires data and then compares the
min/max values from the current acquisition with those stored from previous
acquisitions. The final display shows the most extreme values for all the
acquisitions for each point in the waveform record.
Average Mode. Average mode lets you acquire and display a waveform record
that is the averaged result of several acquisitions. This mode reduces random
noise. The oscilloscope acquires data after each trigger event using Sample
mode. It then averages the record point from the current acquisition with those
stored from previous acquisitions.
Peak Detect Mode. Peak Detect mode alternates between saving the highest
sample in one acquisition interval and lowest sample in the next acquisition
interval. Peak Detect mode only works with real-time, noninterpolated sampling.
If you set the time base so fast that it requires real-time interpolation or
equivalent-time sampling, the mode automatically changes from Peak Detect to
Sample, although the menu selection will not change.