> Are the PC based oscilliscopes any good? E.g. comparable to
> stand alone devices in the same price range.
Well that would depend on what you need. There are certain
circumstances where an analog scope is a practical must, while there are
circumstances where a digital scope are a must. PC Scopes are great for what
they are, slow digital scopes. But don't expect them to replace an analog
scope. I consider them a good supplement to a good analog scope, they have
storage capabilities that can be very useful. If I had to choose between a
PC scope and an analog scope I would probably pick an analog unless I
already had one. Just my opinion. TTYL
Greg Miller wrote:
>Are the PC based oscilliscopes any good? E.g. comparable to stand alone
devices in the same price range.
>
They have their place. The most important thing to remember is that,
from a practical viewpoint, a digital [ie, sampling] scope has to
sample 5 to 10 times per period on a signal to produce a high
fidelity "time-domain" display -[although some scopes do a sinX/X
reproduction and can get away with fewer samples].
In short, this means if you want a digital scope that has the same
ability to display data as a 100 Mhz analog scope, for example, it
has to be able to sample at upwards to 500-1000 Msamples/sec. You
can get 100 Mhz analog scopes for under $1000, but the digital scope
will cost a tad bit more.
On Sat, Mar 17, 2001 at 12:24:53PM -0500, Dan Michaels wrote:
>
> They have their place. The most important thing to remember is that,
> from a practical viewpoint, a digital [ie, sampling] scope has to
> sample 5 to 10 times per period on a signal to produce a high
> fidelity "time-domain" display -[although some scopes do a sinX/X
> reproduction and can get away with fewer samples].
>
> In short, this means if you want a digital scope that has the same
> ability to display data as a 100 Mhz analog scope, for example, it
> has to be able to sample at upwards to 500-1000 Msamples/sec. You
> can get 100 Mhz analog scopes for under $1000, but the digital scope
> will cost a tad bit more.
>
It is true only for "one time" signals. For periodic or "quasi periodic"
signals another techniques may be used (eg. synchroscope or random repetitive
sampling).
Ca. 12 years ago I and my friends have built for our MSc thesis a simple
digital osciloscope which used a very cheap A/D converter with 1ms conversion
time, but time resolution was ca. 1 ns!!!
Using the 16F877 A/D converters and additional sample&hold circuits and
a few logic chips (counters & regisers - may be replaced with single EPLD
device) it should be possible to build the digital oscilloscope with
100 MHz bandwidth, still offering the reasonable reconstruction time...
--
Wojciech Zabolotny .....wzabKILLspam.....ise.pw.edu.pl
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