Introduction
All of today’s high-speed real-time
sampling oscilloscopes use various
forms of digital signal processing
(DSP) on digitized oscilloscope
waveforms. Some engineers are
concerned that filtering digitized
data with software may alter the
true nature of a captured signal.
However, the captured waveform is
only a representation of the actual
input signal, and “raw” digitized
data captured by an oscilloscope
includes altered/distorted results
contributed by the scope’s
front-end hardware filtering.
In a perfect world, real-time
oscilloscopes would have infinitely
fast sample rates, perfectly flat
frequency responses, linear phase
responses, no noise, and infinite
bandwidth. But in the real world,
oscilloscopes have hardware
limitations that produce errors.
DSP filtering ultimately can correct
for hardware-induced errors to
improve measurement accuracy
and enhance display quality.