[sdiy] USB o-scope - just FYI

[neil.johnson97 at ntlworld.com]

From: "Paul Perry"
 
> Well that first one has a "bandwidth" of 25Mhz - but note
> the sample rate of 100M/S...

So the 25MHz limitation would be in the analogue front end (anti-alias filter before the ADC).

> Doesn't that mean that if you are examining a 25Mhz sine
> wave, it's going to have only four sample points on it?

About that.  Which is sufficient to identify a 25MHz sinewave (thank you Mr. Shannon).

> You'll never be able to chase spikes with something like
> this..

But you wouldn't see the spikes on a 25MHz analogue scope either.

> I'd much rather have a secondhand 100MHz analog scope,
> which in some countries can be found quite cheaply.

Amen to that.

Neil


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