Hi It would be far easier to just use a (stock) 48 bit chip than to try to get something like that up and running ….. Keeping all the transitions “just right” would be tough. If you don’t do that, you have a major added source of spurs.
Bob > On Oct 8, 2020, at 10:14 AM, Lester Veenstra via time-nuts > <[email protected]> wrote: > > This I suspect is not original, but with respect for the need for 48 bit > resolution, why not, say, a 24 bit, with reduced range such that it's steps > are the same as what you would see with 48 bits, this stacked (Biased) on a > fixed stable voltage in middle of expected control range. Fixed voltage > could be sourced from an initial courser wide range device. > > Since this seems so obvious, who did it first? > > Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y > [email protected] > > 452 Stable Ln (HC84 RFD USPS Mail) > Keyser WV 26726 > > GPS: 39.336826 N 78.982287 W (Google) > GPS: 39.33682 N 78.9823741 W (GPSDO) > > > Telephones: > Home: +1-304-289-6057 > US cell +1-304-790-9192 > Jamaica cell: +1-876-456-8898 > > > -----Original Message----- > From: time-nuts [mailto:[email protected]] On Behalf Of Hal > Murray > Sent: Wednesday, October 07, 2020 6:18 PM > To: Discussion of precise time and frequency measurement > Cc: [email protected] > Subject: Re: [time-nuts] Aging 5065A ? > > > [email protected] said: >> If you want to run a fixed / well regulated C Field, a DDS with (say) 48 > bits >> would allow you to tune the device well past parts in 10^-15. > > I don't know how to think about a DDS in this context. > > I remember years ago thinking that a DDS was the greatest thing since sliced > > bread. In the context of something like a PPS going into a PC for > timekeeping, that's probably true. You get long term accuracy and the PC > can't see the short term issues. > > But then, somebody mentioned close-in spurs. They get closer the more bits > you have in the DDS magic number. (What is that number called?) > > > Suppose I have a black box labeled "10 MHz" with a cable coming out. > > If you plug that cable into your ADEV measuring setup, can you tell if my > box > has a DDS in it? > > If you plug that cable into your spectrum analyzer, how good a setup do you > need in order to see the spurs? Do they get lost in the close in noise? Or > > maybe the question should be how clean a signal do I need to start with > before > the spurs become visible? Or what should I be asking? > > > -- > These are my opinions. I hate spam. > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
