k5nwa wrote: > At 12:04 PM 1/24/2010, you wrote: >> >> Thanks for your explanations, Bob! >> >> I understand the principles of driving the mixer with a squarewave >> signal and that you use a comparator to change sine to squarewave. >> >> Where I'm failing at is the trick how to receive 30 mhz with a DDS >> that make 37 MHz max without getting problems with nyquist. Can you >> use a comparator to double your VCO frequency without getting >> problems at the duty cycle? >> >> >> Stephan >> > > This is a mixer, you are not trying to digitize the 30MHz signal > where you would need a minimum of two samples, instead you are mixing > it down to the base band.
No but the DDS chip is synthesising a sine wave from samples, and Nyquist bite both ways. However some DDS chips (I don't know about this one have on-board frequency multipliers... > > > Cecil > k5nwa > www.softrockradio.org www.qrpradio.com > < http://parts.softrockradio.org/ > > > Never take life seriously. Nobody gets out alive anyway. > > > > ------------------------------------ > > Yahoo! Groups Links > > > >
