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February
2005, Issue 175
Test Your
EQ
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Answer
8—A
dual-trace oscilloscope has two vertical amplifiers, and
it offers a couple of ways of showing two traces on the
screen in a time-multiplexed fashion.
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Alternating: On each trigger, one channel or the other
is displayed in a repeating sequence. This works well
if both channels are displaying repetitive signals and
the triggers occur relatively often.
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Chopped: On each trigger, both channels are displayed
by rapidly switching between them using an oscillator
built into the oscilloscope. This mode works better
if the triggers are relatively slow, the sweep speed
is slow, or if the signals are not strictly repetitive.
In
contrast, a dual-beam oscilloscope uses a special CRT
that can literally display two independent signals simultaneously.
This type of oscilloscope has fallen out of use because
of advances in digital storage technology, which can also
achieve true simultaneous sampling.
Contributor:
David Tweed
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