Hi > On Dec 8, 2015, at 11:20 PM, Jim Lux <[email protected]> wrote: > > On 12/8/15 3:31 PM, Bob Camp wrote: >> Hi >> >> Let’s see: >> >> EFC uses reference out of the OCXO. >> EFC comes on the OCXO at no added cost. >> 16 bit DAC costs ~$2 to $5 >> >> Total cost for EFC setup $2 to $5. Net result is a system with >> spurs that are how ever far down you wish them to be. (It’s all >> about grounding in this case). >> >> Bob >> > > If the OCXO has steering, the Q of the resonator has to be lower than if the > OCXO wasn't steerable.
If the OCXO has an oscillator attached to the crystal, it has a lower Q than the crystal it’s self….. The contribution of a “normal” (relatively narrow band) tuning circuit is actually quite small. > > So conceivably (if such things were available) you could get a non-steerable > OCXO with better (very) close in noise. Except when you actually wire up that circuit that’s not the outcome. > > And then move the frequency with the DDS. It's fairly straightforward to > make a DDS circuit that pushes the spurs and such away from the carrier (at > the expense of higher noise farther out). Which gets you into a variety of spur and noise issues if you want those spurs to be below the noise floor of a good OCXO. Getting them into the -130 to -150 db down range is far from trivial even with the spreading stuff. > > But hey, that's brand new and exotic. And it pushes the spurs out to where the noise floor should be -170 or -180 … hmmm …. Bob > > _______________________________________________ > 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. _______________________________________________ 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.
