Clever! At least for your spectral measurements the signal never leaves the digital domain. What is the width of the multipliers involved in the mixing? Can you give me a clue, which ADCs you are working with in the front end? > > ....In this application, DDS artifacts would ultimately show up as spurs > on phase noise plots or as ripple in ADEV plots.....
This matches exactly my own observations in terms of ripple in the Tau-Sigma digram when i used a standard like DDS from AD for this purpose. Exactly this is why I got interested in the XILNX DDS compiler. May be the ALTERA stuff is on the same level. Have used ALTERA FPGAs and CPLDs in the past but currently I am devoted to XILINX due to the easier availability in Germany. Best regards Ulrich Bangert, DF6JB Am 21.06.2011 um 12:10 schrieb John Miles: >>> to provide SFDR up to 150 dB (and I'd notice it if I were >>> getting much less than that in practice.) >> >> has pushed me up! When I tell the compiler to generate me a 150 dB SFDR >> DDS >> then it produces an block with 28 (!) bits output witdh for the DAC. So, I >> am asking myself what wonder-chips you may be using as DAC for your DDS >> that >> features a dynamic range high enough to really measure a 150 dB SFDR? > > It's being used as part of a digital downconverter in my case, not driving a > DAC. In this application, DDS artifacts would ultimately show up as spurs > on phase noise plots or as ripple in ADEV plots. I haven't seen any > unaccounted-for spurs above -130 to -140 dBc (where they could be coming > from pretty much anywhere), so I've been happy with the core's real-world > performance. > > -- john, KE5FX > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. Ulrich Bangert Ortholzer Weg1 27243 Gross Ippener Deutschland Tel +49 (0)4224 95071 Fax +49 (0)4224 95072 Mob +49 (0)172 8006546 www.ulrich-bangert.de _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
