On Tue, Oct 6, 2015 at 2:16 AM, Philipp Burch <[email protected]> wrote: > Hi Jon! > > On 06.10.2015 04:44, Jon Elson wrote: >> On 10/05/2015 10:16 AM, Mark Wendt wrote: >>> >>> Well, it does say the "analogue bandwidth" is 2 MHz. It could be >>> using sub-sampling to acheive that bandwidth. >>> >>> >> Even if the analog BW is 2 MHz, if you feed in a 2 MHz >> signal with a 2.5 MSa/sec sampling >> rate, you are bound to get a seriously aliased signal. it >> will probably look like a perfectly clean sine wave at 500 KHz. >> >> Lovely! > > This is absolutely true for simple regular sampling of the signal with a > 1:1 reconstruction. But if you have a good trigger and a periodic input > signal, it is possible to use several periods which are sampled at > slightly shifted points. If you then take all those samples and overlay > them onto a single period, it looks as if you had used a higher sampling > rate. This is sometimes called the "equivalent-time sampling": > http://www.tek.com/document/application-note/real-time-versus-equivalent-time-sampling > > btw: Having a high analog bandwidth (OK, can 2MHz be considered "high"? > Anyway...) is a good thing whatsoever. It usually also means that the > analog frontend won't greatly attenuate your signal or cause a lot of > frequency-dependent phase shift. And it may help you detect some > transients which you would otherwise miss. > > Regards, > Philipp
A similar way of doing it to the article I posted previously. Mark -- One Man, One Machine, One Computer! <VBSEG> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
