Hi Since we are now into the “system”……
Sometimes this alll gets easier at “standard” frequencies. Taking everything down to 1 Hz ( = 1 pps ), 10 Hz, or 100 or 1k KHz might be worth thinking about. Bob > On Jun 21, 2020, at 3:46 PM, Gilles Clement <[email protected]> wrote: > > Dear Ole, > > Very interesting comments, thanks. > I am currently servoing a home brewed local 162kHz oscillator to the incoming > radio signal. The phase difference looks quite clean during day time (ground > wave propagation), but quite dirty at night, (additional fading of such long > wave signals at night ?). Allows me to remove the time phase modulation, and > reach reasonable results. > > What i am planning to do with the 81 divider, is to compare current output > with a « good » 10MHz OCXO (10811) to check with a TIC. > > I am (was) also, indeed, planning to try direct HF signal division to servo > the 10 MHz OCXO. But this may not work well, as you experienced... > > Best, > Gilles. > > >> Le 21 juin 2020 à 16:14, Ole Stender Nielsen via time-nuts >> <[email protected]> a écrit : >> >> Dear Gilles, >> >> If I understand you correctly you will take the French time signal at 162 >> kHz and divide the frequency with 81 in an attempt to compare two 2 kHz >> signals, one originating from the time signal, and another from an OCXO. >> >> However, I would advice not to take the 162 kHz signal and try to divide it >> with 81. The 162 kHz signal you pick off the air is an analog signal, and it >> will suffer from all kinds of unwanted noise, dips and multipath phenomena. >> I assume you plan to condition the signal so that you can feed it to a >> digital divider. However, this is an invitation to cycle slips and jumps. >> >> An off-air frequency reference receiver like the Halcyon OFS-1 fed an >> amplified and filtered 162 kHz signal directly to a divider, and the >> resulting performance was awful. Take a look at >> https://dabbledoo.weebly.com/halcyon-ofs-1.html >> >> If you live very close to the transmitter site, it may work to condition and >> then divide the 162 kHz signal, but if not, you will not be happy. >> >> Best regards >> Ole >> >>> Den 21-06-2020 kl. 09:30 skrev Gilles Clement: >>> 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. > > _______________________________________________ > 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.
