[time-nuts] OT - Portable Digital 'scope

[Orin Eman]

On Thu, Feb 23, 2012 at 2:22 PM, Azelio Boriani <azelio.boriani at screen.it>wrote:

> Actually, undersampling does use the alias effect to bring down the RF
> carrier. That is, the direct sampling radio concept cannot avoid the
> aliasing: it is exploited to avoid, for example, to sample a 2GHz carrier
> modulated with a 20MHz signal with a 4Gsample/second ADC (by the way, does
> it exist?). A simple 20Msample/second ADC would be enough. Yes, to analyze
> an analog signal in real time I doubt you can use this method, if the
> signal is periodic maybe... you can advance the sampling trigger a bit,
> cycle by cycle, and reconstruct the whole signal after this little amount
> has covered a full cycle.
>

Yes.  See for example, the description on this (and the seller's other
similar) ebay item(s): 260955742514

Orin.