Option 58 in a FE Rb is an additional sub board which has nothing to do with the physics package control loop.
In an option 58 Rb there are two DDS chips. On 9 January 2017 at 17:48, Scott Stobbe <scott.j.sto...@gmail.com> wrote: > It very well could be. Based on Marks comments, it sounds like the DDS tone > after being squared up is directly driving a 23-bit counter for the 1 PPS > output. > > On Mon, Jan 9, 2017 at 12:17 PM, Bob kb8tq <kb...@n1k.org> wrote: > > > Hi > > > > In most Rb’s (including the FE 56xx’s) the DDS is mixed with a fixed > > microwave > > frequency signal. The DDS only has to make up “part” of the total offset. > > You get > > roughly a three orders of magnitude improvement because of this. Rick has > > gone > > into all the gory details of why it gets done this way in talking about > > the 5071. It > > is the same thing on an Rb. > > > > So, your basic math is correct about a normal DDS. In this case you are > in > > the > > PPT rather than PPB range due to the multiplication. > > > > Bob > > > > > > > On Jan 9, 2017, at 10:40 AM, Scott Stobbe <scott.j.sto...@gmail.com> > > wrote: > > > > > > A 32-bit DDS synthesizing at 1/5 Fs, yields a tuning resolution of ~ 1 > > ppb. > > > So, I would imagine a slightly lower frequency is programmed into the > DDS > > > and the c-field is trimmed to yield a higher precision. If the new > > > synthesized tone you wish to generate is an integer number of DDS codes > > you > > > could start by assuming the c-field is trimmed to be on frequency, but > if > > > the new tone is a fractional number of 32-bit DDS codes you will have > to > > > manually trim if you want higher precision. > > > > > > On Mon, Jan 9, 2017 at 4:48 AM, wb6bnq <wb6...@cox.net> wrote: > > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > -- Clint. *No trees were harmed in the sending of this mail. However, a large number of electrons were greatly inconvenienced.* _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
