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Sampling Modes
The acquisition system can process the data as it is acquired, averaging or enveloping the
waveform data to produce enhanced waveform records. Once the waveform record exists
(enhanced or not), you can use the post processing capabilities of the instrument to further process
that record: perform measurements, waveform math, and so on. Refer to Acquisition Mode on
page 104 for a description of the acquisition modes.
Waveform Record
While sampling on the input signal provides the data that makes up the waveform record for any
given channel, the instrument builds the waveform record through use of some common
parameters ("common" means they affect the waveforms in all channels).
The following figure shows how these common parameters define the waveform record. They
define how much data is taken and from where in the data stream. The parameters are:
 Sample Interval: The time between sample points taken during acquisition.
 Record Length: The number of samples required to fill a waveform record.
 Trigger Point: The trigger point marks the reference zero time in a waveform record. All
waveform samples are located in time (minus and/or plus) with respect to the trigger point.
 Horizontal Position: When horizontal delay is off, the horizontal position is the time from the
first sample taken (first point in the waveform record) to the trigger point (in percent of
samples before the trigger). The trigger point and the horizontal reference are at the same time
in the waveform record.
When horizontal delay is on, the HORIZONTAL POSITION knob controls the horizontal delay
time. The horizontal delay is the time from the trigger point to the horizontal reference.
The waveform record and its defining parameters (horizontal delay on)
The figure above shows that the instrument acquires points in order from left to right.
When all of the points in the waveform record have been sampled and digitized, the waveform
record is stored in acquisition memory and becomes available for display (or use in math
waveforms, storage, and so on).
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