Speaking of old scopes, the first digital scope I got circa 1986 was a Tek with a sample rate around 20 or 50 Msps, bandwidth 100 or 200 MHz. For repetitive signals it dithered the sample clock to reconstruct signals well above the Nyquist frequency over many cycles. It couldn't see fast single event signals, of course.
It also had a pure analog mode. For the time, it was a pretty decent instrument.Unfortunately, I've long forgotten the model number, but it looked like a 24xx series.
Erich
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--- In hp_agilent_equipment@..., Chuck Harris <cfharris@...> wrote:
Hi Peter,
As I said, "any competently designed DSO". An analog scope gives
you the full vertical bandwidth regardless of the timebase setting.
A competently designed DSO should also.
You can be a bit flexible about that requirement, though. If the
aliasing effects are too fast to see at a particular timebase
setting, it would be ok to slow the sample rate until they are
only marginally too fast to see.
-Chuck Harris
Peter Gottlieb wrote:
But it's not just filtering above the Nyquist. There are other ways a sampling
digital scope can give you a wrong picture of reality. If all of these scopes
ran their digitizers constantly at full rate, watched for envelope effects and
so forth they would go a long way towards eliminating these unwanted erroneous
displays.
Peter
On 12/31/2012 10:56 AM, Chuck Harris wrote:
If by "trust" you mean see things faster than the Nyquist
limit, I fully agree.
