Hi Ok, that’s all very do-able with “normal” CMOS logic and standard counter configurations. There is no need for anything exotic. Two divide by 9’s or 4 divide by threes would do the trick. Anything derived from the 74161 will give you a quick low chip count answer. Bert’s XOR divider will give you symmetric output.
Any family from 74ls on should be fast enough. Bob > On Jun 21, 2020, at 3:30 AM, Gilles Clement <[email protected]> wrote: > > Hi, > Comparing a reference signal at 162kHz with local 10MHz ocxo. Expected Adev > 10E-11 at 10sec. > 162kHz / 81 = 2kHz = 10MHz / 5000 > GC > >> Le 21 juin 2020 à 05:49, Bob kb8tq <[email protected]> a écrit : >> >> Hi >> >> *Any* divide approach followed by a flip flop clocked by the input clock >> will meet >> that same basic requirement. While it *sounds* like it would improve things, >> it >> very much depends on the details. >> >> What are you trying to do? What is the input frequency? What is the phase >> noise >> requirement? >> >> Bob >> >>> On Jun 20, 2020, at 2:22 PM, Gilles Clement <[email protected]> wrote: >>> >>> Hi Robert, >>> You are right, its the lambda divider that was discussed. Need to better >>> understand this approach.... >>> 74HC40103 could also do the 81 Pi-divide easily, but I tend to prefer the >>> PICDIV concept where the controller is clocked by the signal to divide (So >>> limited or no noise is added). AVR family could do it, as most of the >>> instructions take only one clock. >>> Gilles. >>> >>> >>>>> Le 20 juin 2020 à 19:48, Robert LaJeunesse <[email protected]> a écrit : >>>> >>>> Gilles, if I read the Calosso-Rubiola paper correctly a Pi divider is >>>> pretty much your standard square-wave producing digital divider, such as a >>>> 74163 (for even divides). There's odd-value (3,5,7) Pi dividers shown at >>>> https://www.theremin.us/Circuit_Library/symmetrical_digital_dividers.html. >>>> What the Calosso-Rubiola paper promotes is the Lambda divider, which is >>>> depicted in figure 2 of the paper. >>>> >>>> Bob L. >>>> >>>>> Sent: Friday, June 19, 2020 at 10:27 AM >>>>> From: "Gilles Clement" <[email protected]> >>>>> To: "Poul-Henning Kamp" <[email protected]> >>>>> Cc: "Discussion of precise time and frequency measurement" >>>>> <[email protected]> >>>>> Subject: Re: [time-nuts] Frequency division by 81 >>>>> >>>>> Hi, >>>>> Could you point me to a practical design example of a Pi divider ? >>>>> >>>>> >>>>> Envoyé de mon iPad >>>>> >>>>>>> Le 19 juin 2020 à 08:56, Poul-Henning Kamp <[email protected]> a >>>>>>> écrit : >>>>>> >>>>>> -------- >>>>>> >>>>>>> I need to divide the output of an OCXO by a factor D=81 for testing >>>>>>> purposes. So with minimum added phase noise. >>>>>> >>>>>> Two stages of divide by 9 PI-dividers ? >>>>>> >>>>>> http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf >>>>>> >>>>>> -- >>>>>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >>>>>> [email protected] | TCP/IP since RFC 956 >>>>>> FreeBSD committer | BSD since 4.3-tahoe >>>>>> Never attribute to malice what can adequately be explained by >>>>>> incompetence. >>>>> >>>>> _______________________________________________ >>>>> 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. >> >> >> _______________________________________________ >> 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.
