> 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...
The trick is that Nyquist still holds. You can capture a 1 GHz signal with a 40 MHz ADC as long as the signal bandwidth is only 20 MHz. It may get tricky to build an anti-aliasing filter with those parameters. As Jim said, the analog front end and sample-hold needs the raw bandwidth and the clock driving the sample-hold needs good accuracy. -- These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
