TDS 620A, 640A, & 644A User Manual
Acquisition ModesThe acquisition system has several options for converting analog data into
digital form. The Acquisition menu lets you determine the acquisition mode,
whether or not to permit equivalent time sampling, and how to start and stop
acquisitions.
The digitizing oscilloscope supports five acquisition modes.
Sample
Peak Detect
Hi Res
Envelope
Average
The Sample, Peak Detect, and Hi Res modes operate in real-time on a single
trigger event, provided the digitizing oscilloscope can acquire enough samples
for each trigger event. Envelope and Average modes operate on multiple
acquisitions. The digitizing oscilloscope averages or envelopes several wave-
forms on a point-by-point basis.
Figure 3-1 illustrates the different modes and lists the benefits of each. It will
help you select the appropriate mode for your application.
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.) This is the default mode.
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, non-interpolated 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.