I agree that the DDS is not the best and I never said so, I was just refering to the phase noise. The spurs, aliases and digital artifacts are the problem and the newer DDS from Analog are getting better and by using very high frequency clock, 14 bit DACs and some other improvements minimize the spurs, in particular when the output frequency is low.
Regarding the phase noise: > *Phase noise at the output is that of the > DDS clock source times the ratio of the > output frequency to the clock frequency, > as limited by divider noise. The output frequency is always lower than the clock frequency which means that the phase noise will be reduced. The higher the clock frequency the better. The problem is to obtain a good clock. The SDR-100 uses a clock of only 125 MHz but that oscillator costs something like $65.00 and cannot be bought in single unit. The newer DDS use 500 & 1000 MHz clocks and finding one is the problem. I am still looking for a good LO for my project. As it will be modular I can start with a DDS-60 to see what performance I can get. For the 9 MHz IF I will put the SoftRock Oscillator off board to play with different oscillators, the phase noise of that oscillator must be excellent but as it is a "low" fixed frequency it is easier to build. Jean-Claude PJ2BVU ------------------------ Yahoo! Groups Sponsor --------------------~--> Get to your groups with one click. Know instantly when new email arrives http://us.click.yahoo.com/.7bhrC/MGxNAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
