Specifications

Figure 31

The white trace is the reference waveform that was saved to internal memory (a reference waveform

can also be saved to a flash drive). The yellow trace is the signal on channel 1 of the scope. The

easiest way to compare these two signals is to adjust the vertical position of channel 1's signal. In the

situation shown in the picture, the two signals are exact matches. A signal amplitude change of 1% is

discernible and a 2% change is easy to see.

Recording waveforms

We've seen that the digital oscilloscope can capture and display a signal. However, it can happen that

the signal changes over a time substantially longer than the captured time. The oscilloscope may

include a recording feature which will record and save sequential waveforms. This can let you see how

a waveform trace changes over time. Here's a pictorial representation of how it works, where w

is a

single capture waveform:

Figure 32

You pick a time Δt that you wish to have between stored waveforms and set the scope to a sweep time

< Δ t). When you start the recording process, the scope waits for a trigger. When triggered, it

records waveform w

, waits for a period of Δ t, rearms the trigger, and waits to capture the next

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