Actually, for a narrow-band signal, you only have to sample at twice the BANDWIDTH, not twice the frequency. So long as there are no interfering signals around (reasonably accurate when measuring a transmitter), so-called "undersampling" works fine so long as:
1. The sample rate is more than twice the bandwidth. 2. None of the harmonics (sample_rate/2) fall close to the signal. Al N1AL On Tue, 2008-04-29 at 11:05, Romanchik Dan wrote: > Sampling at twice the bandwidth will allow you to accurately extract > frequency information about a signal, or if all you were viewing were > sine waves. To view the actual waveform, however, you really want to > sample at at least 4x or 5x the bandwidth, or, even better, 10x the > bandwidth. > > 73! > > Dan KB6NU > ---------------------------------------------------------- > CW Geek and MI Affiliated Club Coordinator > Read my ham radio blog at http://www.kb6nu.com > LET'S GET MORE KIDS INTO HAM RADIO! > > > > On Apr 29, 2008, at Apr 29, 1:32 PM, Stephen Prior wrote: > > > On a related topic, does anyone have any experience of using the > > usb types > > of 'oscilloscopes' which appear on eBay- dual channel 60MHz > > bandwidth and > > 150Mb/s sampling rate? It's a neat and cost-effective way of > > displaying the > > transmitted waveform for those of us without desk/bench room for a > > 'proper' > > scope. > > > > I've always been led to believe that sampling at twice the > > bandwidth is a > > decent decent rule of thumb and this one is better than that. > > > > I'd be grateful for any advice from someone who has one. > > > > Thanks > > > > Stephen G4SJP > > > > KX-1, K2, K3 almost! > > > > > > > > _______________________________________________ > > Elecraft mailing list > > Post to: Elecraft@mailman.qth.net > > You must be a subscriber to post to the list. > > Subscriber Info (Addr. Change, sub, unsub etc.): > > http://mailman.qth.net/mailman/listinfo/elecraft > > > > Help: http://mailman.qth.net/subscribers.htm > > Elecraft web page: http://www.elecraft.com > > > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
