Re: DAC requirement for carrier generation

Steve Pope wrote:

Paul Solomon <psolomon@xxxxxxxxxx> wrote:



Sampling Frequency needs to be greater then the 2 * the highest frequency you are generating.

so for 160MSPS, the a sinusoidal would need to be < 80MHz.

if you have a modulated carrier there with a bandwidth of say 2 MHZ, then your fc would need to be < 79MHz so that the highest frequency is < 80MHz. (fc + bw/2) < fs/2

fc = center frequency
bw = bandwidth
fs = sampling frequency




Great theoretical answer.  But you'd have real trouble isolating
such a 79 MHz signal from its alias at 81 MHz.

The real question is, could you get by at Fs/3 for the center
frequency?  Or must it be lower still?

Steve


I'm not sure it even makes theoretical sense, considering the sinc rolloff that close to the end of the band (or do theoretician's DACs output dirac pulses :-) ).

Fs/3 can be workable, but a lot depends on the spur performance of the DAC, and a hundred other messy details.

Regards,
Steve
.