If by "trust" you mean see things faster than the Nyquist
limit, I fully agree.
However, any competently designed DSO won't allow signals
faster than the Nyquist limit into the sampling stages...
They typically have a brickwall lowpass filter set at some
point significantly below the Nyquist limit to prevent such
aliasing.
Older DSO's that had very shallow storage areas frequently
allowed a very sparse representation of the signal to show
on screen. This, when combined with simple vector connect
display methods allowed a variety of interesting Moire patterns
to show on the screen... thus confusing things greatly.
However, modern DSO's don't seem to suffer from that problem.
The 70MHz bandwidth spec isn't specmanship. It tells you that
the amplifiers will pass a 70MHz signal with 3dB attenuation.
This spec gives you some assurance that the analog stages won't
be distorting the signals being sampled significantly.
-Chuck Harris
J. Forster wrote:
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You can play with sampling specs, but 40MS/sec gives a Nyquist limit of 20
MHz.
IMO, you simply cannot trust what you see on the screen of a sampling scope.
-John
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