Jim, As you are thinking about this, take another look at John (K2OX) Eckert's work at http://www.exothink.com/SDR/ His measurements might shed some light on the discussion.
Tom W0IVJ Jim Lux wrote: >At 07:39 PM 10/6/2007, Gerald Youngblood wrote: > > >>Phil, I am afraid your jitter specs are not accurate. TI performed custom >>measurements for us last November on the SN65LVDT34. They measured the >>additive jitter at 156.25 MHz to be less than 0.5 ps rms over 10kHz to 40 >>MHz. They phase noise plots they sent show -140 dBc/Hz at 10 kHz offset. >>It is -130 dBc/Hz at 1 kHz. I have the plots and jitter measurements on >>file. >> >> > >That's the "residual" phase noise due to the LVDS driver? (what it >adds to an ideal input sine) So it shows a 1/f kind of characteristic >for the phase noise? (which is sort of what I would expect, as >opposed to the classic resonator 1/f^2 characteristic). > >So, the overall characteristics would be the DDS output (which is >probably dominated by the reference oscillator, which is a 1/f^2, at >least in the few hundred hertz and out range) plus the 1/f noise of >the LVDS part plus the effect of the QSD (which I'll have to go >figure out or read), plus any analog noise at various places. > >And, then, there's the A/D clock effects. > > > > >_______________________________________________ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >FlexRadio Knowledge Base: http://kb.flex-radio.com/ >FlexRadio Homepage: http://www.flex-radio.com/ > > > > > > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
